Cirrus CS5378-IS Low-power single-channel decimation filter Datasheet

CS5378
Low-power Single-channel Decimation Filter
Features
Description
z Single-channel Digital Decimation Filter
ΠMultiple On-chip FIR and IIR Coefficient Sets
ΠProgrammable Coefficients for Custom Filters
ΠSynchronous Operation
z Integrated PLL for Clock Generation
Π1.024 MHz, 2.048 MHz, or 4.096 MHz Input
ΠStandard Clock or Manchester Input
z Selectable Output Word Rate
Π4000, 2000, 1000, 500, 333, 250 SPS
Π200, 125, 100, 50, 40, 25, 20, 10, 5, 1 SPS
z Digital Gain and Offset Corrections
z Test DAC Bit-stream Generator
ΠSine Wave or Impulse Output Mode
z Time Break Controller, General-purpose I/O
z Microcontroller or EEPROM Configuration
z Small-footprint, 28-pin SSOP Package
z Low Power Consumption
Π16 mW at 500 SPS OWR
z Flexible Power Supplies
ΠI/O Interface and PLL: 3.3 V or 5.0 V
ΠDigital Logic Core: 2.5 V, 3.3 V or 5.0 V
The CS5378 is a multi-function digital filter utilizing a lowpower signal processing architecture to achieve efficient
filtering for a delta-sigma-type modulator. By combining
the CS5378 with a CS3301/02 differential amplifier, a
CS5371 modulator, and a CS4373 test DAC, a synchronous high-resolution measurement system can be
designed quickly and easily.
Digital filter coefficients for the CS5378 FIR and IIR filters
are included on-chip for a simple setup, or they can be
programmed for custom applications. Selectable digital
filter decimation ratios produce output word rates from
4000 SPS to 1 SPS, resulting in measurement bandwidths ranging from 1600 Hz down to 400 mHz when
using the on-chip coefficient sets.
The CS5378 includes integrated peripherals to simplify
system design: a low-jitter PLL for standard clock or
manchester inputs, offset and gain corrections, a test
DAC bit stream generator, a time break controller, and
eight general-purpose I/O pins.
ORDERING INFORMATION
See page 86.
VDDCORE
VDDPLL
VDDPAD
DRDY
MISO
MOSI
SCK
SS:EECS
I
PLL, Clock Generation
Serial Interface
http://www.cirrus.com
RESET
SYNC
MSYNC
Time Break Controller
TIMEB
Test Bit Stream
Controller
TBSDATA
GPIO7:BOOT
GPIO6:PLL2
GPIO5:PLL1
GPIO4:PLL0
GPIO3
GPIO2
GPIO1
GPIO0
GNDCORE
GPIO
General Purpose I/O
GNDPLL
MFLAG
MDATA
Modulator Data Interface
MCLK
Reset, Synchronization
GNDPAD
Decimation and
Filtering Engine
CLK
Copyright © Cirrus Logic, Inc. 2005
(All Rights Reserved)
OCT ‘05
DS639F1
CS5378
TABLE OF CONTENTS
1. General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.
1.2.
1.3.
1.4.
Digital Filter Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Integrated Peripheral Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
System Level Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Configuration Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2. Characteristics and Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Specified Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Digital Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Power Consumption. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Switching Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
3. System Design with CS5378 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1.
3.2.
3.3.
3.4.
3.5.
3.6.
3.7.
3.8.
Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Reset Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
PLL and Clock Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
System Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Digital Filter Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Integrated peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4. Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.1. Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
4.2. Bypass Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
4.3. Power Consumption. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
5. Reset Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1. Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.2. Reset Self-Tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.3. Boot Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
6. PLL and Clock Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.1.
6.2.
6.3.
6.4.
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
PLL Mode Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Synchronous Clocking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Master Clock Jitter and Skew. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
7. Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.1.
7.2.
7.3.
7.4.
7.5.
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
MSYNC Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Digital Filter Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Modulator Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Test Bit Stream Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
8. Configuration By EEPROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.1.
8.2.
8.3.
8.4.
8.5.
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
EEPROM Hardware Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
EEPROM Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
EEPROM Configuration Commands . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Example EEPROM Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
9. Configuration By Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
DS639F1
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CS5378
9.1.
9.2.
9.3.
9.4.
9.5.
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Microcontroller Hardware Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Microcontroller Serial Transactions . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Microcontroller Configuration Commands . . . . . . . . . . . . . . . . . . . . . . .33
Example Microcontroller Configuration . . . . . . . . . . . . . . . . . . . . . . . . .35
10. Modulator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.1.
10.2.
10.3.
10.4.
10.5.
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Modulator Clock Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Modulator Synchronization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Modulator Data Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Modulator Flag Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
11. Digital Filter Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
11.1. Filter Coefficient Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
11.2. Filter Configuration Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
12. SINC Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
12.1.
12.2.
12.3.
12.4.
SINC1 Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
SINC2 Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
SINC3 Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
SINC Filter Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
13. FIR Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
13.1.
13.2.
13.3.
13.4.
13.5.
FIR1 Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
FIR2 Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
On-Chip FIR Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Programmable FIR Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
FIR Filter Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
14. IIR Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
14.1.
14.2.
14.3.
14.4.
14.5.
14.6.
14.7.
IIR Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
IIR1 Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
IIR2 Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
IIR3 Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
On-Chip IIR Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
Programmable IIR Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
IIR Filter Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
15. Gain and Offset Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
15.1. Gain Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
15.2. Offset Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
15.3. Offset Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
16. Serial Data Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
16.1. Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
16.2. Serial Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
16.3. Serial Data Transactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
17. Test Bit Stream Generator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
17.1.
17.2.
17.3.
17.4.
17.5.
17.6.
DS639F1
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
TBS Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
TBS Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
TBS Data Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
TBS Sine Wave Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
TBS Impulse Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
3
CS5378
17.7. TBS Loopback Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
17.8. TBS Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
18. Time Break Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
18.1. Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
18.2. Time Break Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
18.3. Time Break Delay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
19. General Purpose I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
19.1.
19.2.
19.3.
19.4.
19.5.
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
GPIO Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
GPIO Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
GPIO Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
GPIO Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
20. Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
20.1. SPI Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
20.2. Digital Filter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
21.
22.
23.
24.
25.
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Package Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Environmental, Manufacturing, & Handling Information . . . . . . . . . . 86
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
LIST OF FIGURES
Figure 1. CS5378 Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 2. Digital Filtering Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 3. FIR and IIR Coefficient Set Selection Word . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 4. MOSI Write Timing in SPI Slave Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 5. MISO Read Timing in SPI Slave Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 6. Serial Data Read Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 7. SYNC, MCLK, MSYNC, MDATA Interface Timing. . . . . . . . . . . . . . . . . . . . . 16
Figure 8. TBS Output Data Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 9. Single-Channel System Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 10. Power Supply Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 11. Reset Control Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 12. Clock Generation Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 13. Synchronization Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 14. EEPROM Configuration Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 15. EEPROM Serial Read Transactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 16. 8 Kbyte EEPROM Memory Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 17. Serial Interface Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 18. Microcontroller Serial Transactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 19. SPI Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 20. Modulator Data Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 21. Digital Filter Stages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Figure 22. FIR and IIR Coefficient Set Selection Word . . . . . . . . . . . . . . . . . . . . . . . . . 39
Figure 23. SINC Filter Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Figure 24. SINC Filter Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Figure 25. FIR Filter Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 26. FIR Filter Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
DS639F1
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CS5378
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
Figure 35.
Figure 36.
Figure 37.
Figure 38.
Figure 39.
Figure 40.
Figure 41.
Figure 42.
Figure 43.
Figure 44.
Figure 45.
Figure 46.
Figure 47.
Figure 48.
Figure 49.
Figure 50.
Figure 51.
Figure 52.
Figure 53.
Figure 54.
FIR1 Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FIR2 Linear Phase Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FIR2 Minimum Phase Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IIR Filter Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IIR Filter Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gain and Offset Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Serial Data Interface Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32-bit Serial Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SD Port Transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Bit Stream Generator Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . .
Time Break Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GPIO Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPI Control Register SPICTRL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPI Command Register SPICMD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPI Data Register SPIDAT1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPI Data Register SPIDAT2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hardware Configuration Register CONFIG. . . . . . . . . . . . . . . . . . . . . . . . . .
GPIO Configuration Register GPCFG . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter Configuration Register FILTCFG . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gain Correction Register GAIN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Offset Correction Register OFFSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Time Break Counter Register TIMEBRK . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Bit Stream Configuration Register TBSCFG. . . . . . . . . . . . . . . . . . . . .
Test Bit Stream Gain Register TBSGAIN . . . . . . . . . . . . . . . . . . . . . . . . . . .
User Defined System Register SYSTEM1 . . . . . . . . . . . . . . . . . . . . . . . . . .
Hardware Version ID Register VERSION . . . . . . . . . . . . . . . . . . . . . . . . . . .
Self Test Result Register SELFTEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CS5378 Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
49
50
51
52
54
56
58
58
59
60
63
64
67
68
69
70
72
73
74
75
76
77
78
79
80
81
82
83
LIST OF TABLES
Table 1. Microcontroller and EEPROM Configuration Commands . . . . . . . . . . . . . . . . . 9
Table 2. TBS Configurations Using On-Chip Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 3. SPI and Digital Filter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 4. PLL and BOOT Mode Reset Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 5. PLL Mode Selections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 6. Maximum EEPROM Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 7. EEPROM Boot Configuration Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 8. Example EEPROM File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 9. Microcontroller Boot Configuration Commands . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 10. Example Microcontroller Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 11. SINC Filter Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Table 12. SINC1 and SINC2 Filter Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 13. SINC3 Filter Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Table 14. FIR Filter Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Table 15. SINC + FIR Group Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 16. Minimum Phase Group Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table 16. IIR Filter Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 17. IIR Filter Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 18. TBS Configurations Using On-Chip Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Table 19. TBS Impulse Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
DS639F1
5
VDDCORE
VDDPLL
VDDPAD
DRDY
MISO
MOSI
SCK
SS:EECS
CS5378
PLL, Clock Generation
CLK
MCLK
Reset, Synchronization
RESET
SYNC
MSYNC
Time Break Controller
TIMEB
Serial Interface
Decimation and
Filtering Engine
Test Bit Stream
Controller
GPIO7:BOOT
GPIO6:PLL2
GPIO5:PLL1
GPIO4:PLL0
GPIO3
GPIO2
GPIO1
GPIO0
GNDCORE
GNDPAD
MFLAG
MDATA
GNDPLL
GPIO
General Purpose I/O
Modulator Data Interface
TBSDATA
Figure 1. CS5378 Block Diagram
1. GENERAL DESCRIPTION
The CS5378 is a single channel digital filter with
integrated system peripherals. Figure 1 illustrates a
simplified block diagram of the CS5378.
40, 25, 20, 10, 5, 1 SPS.
•
1.1 Digital Filter Features
Flexible digital filter configuration. (See Figure
2)
-
Cascaded SINC, FIR, and IIR filters with
selectable output stage.
•
Single channel decimation filter for CS5371 ∆Σ
modulator.
-
•
Synchronous operation for simultaneous sampling in multi-sensor systems.
Linear and minimum phase FIR low-pass
filter coefficients included.
-
3 Hz Butterworth IIR high-pass filter coefficients included.
-
FIR and IIR coefficients programmable to
create a custom filter response.
•
Internal synchronization of digital filter
phase to an external SYNC signal.
Output word rates, including low bandwidth
rates.
-
Standard output rates: 4000, 2000, 1000,
500, 333, 250 SPS.
-
Low bandwidth rates: 200, 125, 100, 50,
DS639F1
•
Digital gain correction to normalize sensor
gain.
•
Digital offset correction and calibration.
-
Offset correction to remove measurement
6
CS5378
Modulator
Input
512 kHz
Sinc Filter
2 - 64000
FIR1
FIR2
4
Gain &
DC Offset
Corrections
IIR1
st
2
1 Order
IIR2
2
nd
Order
Output to High Speed Serial Interface
Output Word Rate from 4000 SPS ~ 1 SPS
Figure 2. Digital Filtering Stages
-
DC offset.
-
Calibration engine for automatic calculation of offset correction factor.
•
1.2 Integrated Peripheral Features
•
•
•
1.024 MHz, 2.048 MHz, 4.096 MHz standard clock or manchester encoded input.
Synchronous operation for simultaneous sampling in multi-sensor systems.
-
•
Time break controller to record system timing
information.
-
Dedicated TB status bit in the output data
stream.
-
Programmable output delay to match system group delay.
Low jitter PLL to generate local clocks.
-
MCLK / MSYNC output signals to synchronize external components.
High speed serial data output.
•
Impulse output mode for transfer function
characterization.
8 General Purpose I/O (GPIO) pins for local
hardware control.
1.3 System Level Features
•
Flexible configuration options.
-
Asynchronous operation to 4 MHz for direct connection to system telemetry.
-
Configuration 'on-the-fly' via microcontroller or system telemetry.
-
Internal 8-deep data FIFO for flexible output timing.
-
Fixed configuration via stand-alone boot
EEPROM.
-
Selectable 24-bit data only or 32-bit status+data output.
Digital test bit stream signal generator suitable
for CS4373 ∆Σ test DAC.
-
Sine wave output mode for testing total harmonic distortion.
DS639F1
•
•
Low power consumption.
-
16 mW at 500 SPS OWR.
-
100 µW standby mode.
Flexible power supply configurations.
-
Separate digital logic core, telemetry I/O,
7
CS5378
and PLL power supplies.
•
-
Telemetry I/O and PLL interfaces operate
from 3.3 V or 5 V.
-
Digital logic core operates from 2.5 V,
3.3 V or 5 V.
Small 28-pin SSOP package.
-
Total footprint 8 mm x 10 mm plus three
bypass capacitors.
1.4 Configuration Interface
•
Configuration from microcontroller or standalone boot EEPROM.
-
tion during operation.
•
EEPROM boot sets a fixed operational configuration.
Configuration commands written through the
serial interface. (See Table 1)
-
Standardized microcontroller interface using SPI registers. (See Table 3)
-
Commands write digital filter registers and
FIR / IIR filter coefficients.
-
Digital filter registers set hardware configuration options.
Microcontroller boot permits reconfigura-
DS639F1
8
CS5378
Microcontroller Boot Configuration Commands
Name
CMD
24-bit
DAT1
24-bit
DAT2
24-bit
Description
NOP
000000
-
-
WRITE DF REGISTER
000001
REG
DATA
Write Digital Filter Register
READ DF REGISTER
000002
REG
[DATA]
-
Read Digital Filter Register
WRITE FIR COEFFICIENTS
000003
NUM FIR1
(FIR COEF)
NUM FIR2
(FIR COEF)
Write Custom FIR Coefficients
WRITE IIR COEFFICIENTS
000004
a11
b11
a22
b21
b10
a21
b20
b22
Write Custom IIR Coefficients
WRITE ROM COEFFICIENTS
000005
COEF SEL
-
Use On-Chip Coefficients
NOP
000006
-
-
No Operation
NOP
000007
-
-
No Operation
FILTER START
000008
-
-
Start Digital Filter Operation
FILTER STOP
000009
-
-
Stop Digital Filter Operation
No Operation
EEPROM Boot Configuration Commands
Name
CMD
8-bit
DATA
24-bit
Description
NOP
00
-
WRITE DF REGISTER
01
REG
DATA
WRITE FIR COEFFICIENTS
02
NUM FIR1
NUM FIR2
(FIR COEF)
Write Custom FIR Coefficients
WRITE IIR COEFFICIENTS
03
a11
b10
b11
a21
a22
b20
b21
b22
Write Custom IIR Coefficients
WRITE ROM COEFFICIENTS
04
COEF SEL
NOP
05
-
No Operation
NOP
06
-
No Operation
FILTER START
07
-
Start Digital Filter Operation
No Operation
Write Digital Filter Register
Use On-Chip Coefficients
[DATA] indicates data word returned from digital filter.
(DATA) indicates multiple words of this type are to be written.
Table 1. Microcontroller and EEPROM Configuration Commands
DS639F1
9
CS5378
Bits
23:20
19:16
15:12
11:8
7:4
3:0
Selection
0000
0000
IIR2
IIR1
FIR2
FIR1
Bits 15:12
IIR2 Coefficients
Bits 11:8
IIR1 Coefficients
Bits 3:0
FIR1 Coefficients
0000
3 Hz @ 2000 SPS
0000
3 Hz @ 2000 SPS
0000
Linear Phase
0001
3 Hz @ 1000 SPS
0001
3 Hz @ 1000 SPS
0001
Minimum Phase
0010
3 Hz @ 500 SPS
0010
3 Hz @ 500 SPS
0011
3 Hz @ 333 SPS
0011
3 Hz @ 333 SPS
Bits 7:4
FIR2 Coefficients
0100
3 Hz @ 250 SPS
0100
3 Hz @ 250 SPS
0000
Linear Phase
0001
Minimum Phase
Figure 3. FIR and IIR Coefficient Set Selection Word
Test Bit Stream Characteristic Equation:
(Signal Freq) * (# TBS Data) * (Interpolation + 1) = Output Rate
Example: (31.25 Hz) * (1024) * (0x07 + 1) = 256 kHz
Signal
Frequency
(TBSDATA)
Output
Rate
(TBSCLK)
Output Rate
Selection
(RATE)
Interpolation
Selection
(INTP)
10.00 Hz
256 kHz
0x4
0x18
10.00 Hz
512 kHz
0x5
0x31
25.00 Hz
256 kHz
0x4
0x09
25.00 Hz
512 kHz
0x5
0x13
31.25 Hz
256 kHz
0x4
0x07
31.25 Hz
512 kHz
0x5
0x0F
50.00 Hz
256 kHz
0x4
0x04
50.00 Hz
512 kHz
0x5
0x09
125.00 Hz
256 kHz
0x4
0x01
125.00 Hz
512 kHz
0x5
0x03
Table 2. TBS Configurations Using On-Chip Data
DS639F1
10
CS5378
SPI Registers
Addr.
Type
# Bits
SPICTRL
Name
00 - 02
R/W
8, 8, 8
SPI Control
Description
SPICMD
03 - 05
R/W
8, 8, 8
SPI Command
SPIDAT1
06 - 08
R/W
8, 8, 8
SPI Data 1
SPIDAT2
09 - 0B
R/W
8, 8, 8
SPI Data 2
Addr.
Type
# Bits
Digital Filter Registers
Name
CONFIG
RESERVED
GPCFG
RESERVED
Description
00
R/W
24
Hardware Configuration
01-0D
R/W
24
Reserved
0E
R/W
24
GPIO[7:0] Direction, Pull-up Enable, and Data
0F-1F
R/W
24
Reserved
FILTCFG
20
R/W
24
Digital Filter Configuration
GAIN
21
R/W
24
Gain Correction
22-24
R/W
24
Reserved
25
R/W
24
Offset Correction
RESERVED
OFFSET
RESERVED
26-28
R/W
24
Reserved
TIMEBRK
29
R/W
24
Time Break Delay
TBSCFG
2A
R/W
24
Test Bit Stream Configuration
TBSGAIN
2B
R/W
24
Test Bit Stream Gain
SYSTEM1
2C
R/W
24
User Defined System Register 1
SYSTEM2
2D
R/W
24
User Defined System Register 2
VERSION
2E
R/W
24
Hardware Version ID
SELFTEST
2F
R/W
24
Self-Test Result Code
Table 3. SPI and Digital Filter Registers
PLL[2:0]
Mode Selection on Reset
BOOT
Mode Selection on Reset
111
32.768 MHz clock input (PLL bypass).
1
EEPROM boot
110
1.024 MHz clock input.
0
Microcontroller boot
101
2.048 MHz clock input.
100
4.096 MHz clock input.
011
32.768 MHz clock input (PLL bypass).
010
1.024 MHz manchester input.
001
2.048 MHz manchester input.
000
4.096 MHz manchester input.
Configuration Note:
States of the PLL[2:0] and BOOT pins are
latched immediately after reset to select modes.
These pins have a weak (~100 kΩ) pull-up resistor enabled by default. An external 10 kΩ
pull-down is required to set a low condition.
Table 4. PLL and BOOT Mode Reset Configurations
DS639F1
11
CS5378
2. CHARACTERISTICS AND SPECIFICATIONS
•
Min / Max characteristics and specifications are guaranteed over the Specified Operating Conditions.
•
Typical performance characteristics and specifications are derived from measurements taken at nominal supply voltages and TA = 25°C.
•
GND, GND1, GND2 = 0 V, all voltages with respect to 0 V.
SPECIFIED OPERATING CONDITIONS
Parameter
Logic Core Power Supply
Symbol
Min
Nom
Max
Unit
VDDCORE
2.375
2.5
5.25
V
VDDPLL
3.135
3.3
5.25
V
VDDPAD
3.135
3.3
5.25
V
TA
-40
-
85
°C
PLL Power Supply
I/O Power Supply
Ambient Operating Temperature
Industrial (-IQ)
ABSOLUTE MAXIMUM RATINGS
Parameter
DC Power Supplies
Symbol
Min
Max
Units
-0.3
-0.3
-0.3
6.0
6.0
6.0
V
V
V
IIN
-
±10
mA
Logic Core VDDCORE
PLL VDDPLL
I/O VDDPAD
Input Current, Any Pin Except Supplies
(Note 1)
Input Current, Power Supplies
(Note 1)
IIN
-
±50
mA
Output Current
(Note 1)
IOUT
-
±25
mA
Power Dissipation
PDN
-
500
mW
Digital Input Voltages
VIND
-0.3
VDD+0.3
V
TA
-40
85
°C
TSTG
-65
150
°C
Ambient Operating Temperature (Power Applied)
Storage Temperature Range
1. Transient currents up to 100 mA will not cause SCR latch-up.
DS639F1
12
CS5378
THERMAL CHARACTERISTICS
Parameter
Symbol
Min
Typ
Max
Unit
TJ
-
-
135
°C
Junction to Ambient Thermal Impedance (4-Layer PCB)
ΘJA
-
50
Ambient Operating Temperature (Power Applied)
TA
-40
-
Symbol
Min
Typ
Max
Unit
High-Level Input Drive Voltage
VIH
0.6 * VDD
-
VDD
V
Low-Level Input Drive Voltage
VIL
0.0
-
0.8
V
Allowable Junction Temperature
°C / W
+85
°C
DIGITAL CHARACTERISTICS
Parameter
High-Level Output Drive Voltage
Iout = -40 µA
VOH
VDD - 0.3
-
VDD
V
Low-Level Output Drive Voltage
Iout = +40 µA
VOL
0.0
-
0.3
V
Rise Times, Digital Inputs
tRISE
-
-
100
ns
Fall Times, Digital Inputs
tFALL
-
-
100
ns
Rise Times, Digital Outputs
tRISE
-
-
100
ns
Fall Times, Digital Outputs
tFALL
-
-
100
ns
Input Leakage Current
IIN
-
±1
± 10
µA
3-State Leakage Current
(Note 2)
IOZ
-
-
± 10
µA
Digital Input Capacitance
CIN
-
9
-
pF
COUT
-
9
-
pF
Digital Output Pin Capacitance
Notes: 2. Maximum leakage for pins with pull-up resistors (RESET, SS:EECS, GPIO, MOSI, SCK) is ±250 µA.
t ris e in
t rise out
t fa llin
t fallo ut
0.902.6
* VDD
V
0.90 * VDD
4 .6 V
0.100.7
* VDD
V
0.10 * 0VDD
.4 V
POWER CONSUMPTION
Parameter
Symbol
Min
Typ
Max
Unit
1.024 MHz Digital Filter Clock
PWR1
-
12
-
mW
2.048 MHz Digital Filter Clock
PWR2
-
14
-
mW
4.096 MHz Digital Filter Clock
PWR4
-
16
-
mW
8.192 MHz Digital Filter Clock
PWR8
-
24
-
mW
PWRS
-
100
-
µW
Operational Power Consumption
Standby Power Consumption
32 kHz Digital Filter Clock, Filter Stopped
DS639F1
13
CS5378
SWITCHING CHARACTERISTICS
Serial Configuration Interface Timing (External Master)
SSI
SS:EECS
MOSI
MSB
LSB
MSB - 1
t1
t2
t3
t4
t5
t6
SCK
SCLK
Figure 4. MOSI Write Timing in SPI Slave Mode
SS I
SS:EECS
t 10
MISO
MSB
MSB - 1
t7
LSB
t8
t9
SCK
SCLK
Figure 5. MISO Read Timing in SPI Slave Mode
Parameter
Symbol
Min
Typ
Max
Unit
SS:EECS Enable to Valid Latch Clock
t1
60
-
-
ns
Data Set-up Time Prior to SCK Rising
t2
60
-
-
ns
Data Hold Time After SCK Rising
t3
120
-
-
ns
SCK High Time
t4
120
-
-
ns
SCK Low Time
t5
120
-
-
ns
SCK Falling Prior to SS:EECS Disable
t6
60
-
-
ns
SCK Falling to New Data Bit
t7
-
-
200
ns
SCK High Time
t8
120
-
-
ns
SCK Low Time
t9
120
-
-
ns
SS:EECS Rising to MISO Hi-Z
t10
-
-
150
ns
MOSI Write Timing
MISO Read Timing
DS639F1
14
CS5378
SWITCHING CHARACTERISTICS
Serial Data Interface Timing
DRDY
SCK
t3
t4
MISO
t1
t2
t5
Figure 6. Serial Data Read Timing
Parameter
Symbol
Min
Typ
Max
Unit
DRDY Falling Edge to SCK Rising
t1
60
-
-
ns
SCK Falling to New Data Bit
t2
-
-
120
ns
SCK High Time
t3
120
-
-
ns
SCK Low Time
t4
120
-
-
ns
Final SCK Falling to DRDY Rising
t5
60
-
-
ns
DS639F1
15
CS5378
SWITCHING CHARACTERISTICS
CLK, SYNC, MCLK, MSYNC, and MDATA
SYNC
MCLK
MSYNC
tmsd
tmsh
tmsd
Data1
MDATA
Data2
Note: SYNC input latched on MCLK rising edge. MSYNC output triggered by MCLK falling edge.
fMCLK
2.048 MHz
1.024 MHz
tmsd = TMCLK / 4
tmsd = 122 ns
tmsd = 244 ns
tmsh = TMCLK
tmsh = 488 ns
tmsh = 976 ns
Figure 7. SYNC, MCLK, MSYNC, MDATA Interface Timing
Parameter
Symbol
Min
Typ
Max
Unit
CLK
32
32.768
33
MHz
Master Clock Duty Cycle
DTY
40
-
60
%
Master Clock Rise Time
tRISE
-
-
20
ns
Master Clock Fall Time
tFALL
-
-
20
ns
Master Clock Jitter
JTR
-
-
300
ps
Master Clock Frequency
(Note 3)
SYNC
-2
-
2
µs
MSYNC Setup Time to MCLK rising
tmss
20
-
-
ns
MCLK rising to Valid MDATA
tmdv
-
-
75
ns
MSYNC falling to MCLK rising
tmsf
20
-
-
ns
Synchronization after SYNC rising
(Note 4)
Notes: 3. PLL bypass mode. The PLL generates a 32.768 MHz master clock when enabled.
4. Sampling synchronization between multiple CS5378 devices receiving identical SYNC signals.
DS639F1
16
CS5378
SWITCHING CHARACTERISTICS
Test Bit Stream (TBS)
TBSDATA
t1
t2
MCLK
Note: Example timing shown for a 256 kHz output rate and no programmable delays.
Figure 8. TBS Output Data Timing
Parameter
Symbol
Min
Typ
Max
Unit
-
256
-
kbps
t1
60
-
-
ns
t2
60
-
-
ns
TBS Data Output Timing
TBS Data Bit Rate
TBS Data Rising to MCLK Rising Setup Time
MCLK Rising to TBS Data Falling Hold Time
(Note 5)
5. TBSDATA can be delayed from 0 to 63 full bit periods. The timing diagram shows no TBSDATA delay.
DS639F1
17
CS5378
System
Telemetry
CS5371
Geophone
or
Hydrophone
Sensor
M
U
X
CS3301
CS3302
∆Σ
Modulator
CS5378
AMP
µController
or
Configuration
EEPROM
Digital Filter
w/ PLL
CS4373
Communication
Interface
∆Σ
Test DAC
Figure 9. Single-Channel System Block Diagram
3. SYSTEM DESIGN WITH CS5378
Figure 9 illustrates a simplified block diagram of
the CS5378 in a single channel measurement system.
A differential sensor is connected through the
CS3301/02 differential amplifiers to the CS5371
∆Σ modulator, where analog to digital conversion
occurs. The modulator’s 1-bit output connects to
the CS5378 MDATA input, where the oversampled ∆Σ data is decimated and filtered to 24-bit output samples at a programmed output rate. These
output samples are buffered into an 8-deep data
FIFO and then passed to the system telemetry.
System self tests are performed by connecting the
CS5378 test bit stream (TBS) generator to the
CS4373 test DAC. Analog tests drive differential
signals from the CS4373 test DAC into the multiplexed inputs of the CS3301/02 amplifiers or directly to the differential sensor. Digital loopback
tests internally connect the TBS digital output directly to the CS5378 modulator input.
DS639F1
3.1 Power Supplies
The system shown in Figure 9 typically operates
from a ±2.5 V or a 5 V analog power supply and a
3.3 V digital power supply. The CS5378 logic core
can be powered from 2.5 V to minimize power consumption, if required.
3.2 Reset Control
System reset is required only for the CS5378 device, and is a standard active low signal that can be
generated by a power supply monitor or microcontroller. Other system devices default to a powerdown state when the CS5378 is reset.
3.3 PLL and Clock Generation
A PLL is included on the CS5378 to generate an internal 32.768 MHz master clock from a
1.024 MHz, 2.048 MHz, or 4.096 MHz standard
clock or manchester encoded input. Clock inputs
for other system devices are driven by clock outputs from the CS5378.
18
CS5378
3.4 Synchronization
3.7 Data Collection
Digital filter phase and analog sample timing of the
∆Σ modulator connected to the CS5378 are synchronized by a rising edge on the SYNC pin. If a
synchronization signal is received identically by all
CS5378 devices in a measurement network, synchronous sampling across the network is guaranteed.
Data is collected from the CS5378 through the serial data interface. When data is available, serial
transactions are automatically initiated to transfer
24-bit data or 32-bit status+data from the output
FIFO to the system telemetry. The output FIFO has
eight data locations to permit latency in data collection.
3.5 System Configuration
3.8 Integrated peripherals
Through the serial configuration interface, filter
coefficients and digital filter register settings can
either be programmed by a microcontroller or automatically loaded from an external EEPROM after
reset. System configuration is only required for the
CS5378 device, as other devices are configured via
the CS5378 General Purpose I/O pins.
Test Bit Stream (TBS)
Two registers in the digital filter, SYSTEM1 and
SYSTEM2 (0x2C, 0x2D), are provided for user defined system information. These are general purpose registers that will hold any 24-bit data values
written to them.
3.6 Digital Filter Operation
After analog to digital conversion occurs in the
modulator, the oversampled 1-bit ∆Σ data is read
into the CS5378 through the MDATA pin. The digital filter then processes data through the enabled
filter stages, decimating it to 24-bit words at a programmed output word rate. The final 24-bit samples are concatenated with 8-bit status words and
placed into an output FIFO.
DS639F1
A digital signal generator built into the CS5378
produces a 1-bit ∆Σ sine wave or impulse function.
This digital test bit stream is connected to the
CS4373 test DAC to create high quality analog test
signals or internally looped back to the CS5378
MDATA input to test the digital filter and data collection circuitry.
Time Break
Timing information is recorded during data collection by strobing the TIMEB pin. A dedicated flag
in the sample status bits, TB, is set high to indicate
during which measurement the timing event occurred.
General Purpose I/O (GPIO)
Eight general purpose pins are available on the
CS5378 for system control. Each pin can be set as
input or output, high or low, with an internal pullup enabled or disabled. The CS3301/02, CS5371
and CS4373 devices in Figure 9 are configured by
simple pin settings controlled through the CS5378
GPIO pins.
19
CS5378
VDDPAD
GNDPAD
1
28
2
27
3
26
4
25
5
24
6
23
7
22
8
21
9
20
10
19
11
18
12
17
13
16
14
15
GNDCORE
VDDCORE
GNDPLL
VDDPLL
Figure 10. Power Supply Block Diagram
4. POWER SUPPLIES
The CS5378 has three sets of power supply inputs.
One set supplies power to the I/O pins of the device
(VDDPAD), another supplies power to the logic
core (VDDCORE) and the third supplies power to
the PLL (VDDPLL). The I/O pin power supplies
determine the maximum input and output voltages
when interfacing to peripherals, the logic core power supply largely determines the power consumption of the CS5378 and the PLL power supply
powers the internal PLL circuitry.
4.1 Pin Descriptions
VDDPAD, GNDPAD - Pins 9, 10
Sets the interface voltage to a microcontroller, system telemetry, modulator, and test DAC. VDDPAD can be driven with voltages from 3.3 V to
5 V.
VDDPLL, GNDPLL - Pins 15, 16
Sets the operational voltage of the internal CS5378
PLL circuitry. Can be driven with voltages from
3.3 V to 5 V.
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VDDCORE, GNDCORE - Pins 21, 22
Sets the operational voltage of the CS5378 logic
core. VDDCORE can be driven with voltages from
2.5 V to 5 V. A 2.5 V supply will minimize total
power consumption.
4.2 Bypass Capacitors
Each power supply pin should be bypassed with
parallel 1 µF and 0.01 µF caps, or by a single
0.1 µF cap, placed as close as possible to the
CS5378. Bypass capacitors should be ceramic
(X7R, C0G), tantalum, or other good quality dielectric type.
4.3 Power Consumption
Power consumption of the CS5378 depends primarily on the power supply voltage of the logic core
(VDDCORE) and the programmed digital filter
clock rate. Digital filter clock rates are selected
based on the required output word rate as explained
in “Digital Filter Initialization” on page 38.
20
CS5378
RESET
Self-Tests
BOOT
Pin
0
1
SELFTEST
Register
EEPROM
Boot
µController
Boot
Figure 11. Reset Control Block Diagram
5. RESET CONTROL
The CS5378 reset signal is active low. When released, a series of self-tests are performed and the
device either actively boots from an external EEPROM or enters an idle state waiting for microcontroller configuration.
combined into the SELFTEST register (0x2F),
with 0x0AAAAA indicating all passed. Self-tests
require 60 ms to complete.
5.3 Boot Configurations
Reset input, active low.
The logic state of the BOOT pin after reset determines if the CS5378 actively reads configuration
information from EEPROM or enters an idle state
waiting for a microcontroller to write configuration
commands.
GPIO7:BOOT - Pin 28
EEPROM Boot
Boot mode select, latched immediately following
reset. Weak (~100 kΩ) internal pull-up defaults
high, external 10 kΩ pull-down required to set low.
When the BOOT pin is high after reset, the CS5378
actively reads data from an external serial EEPROM and then begins operation in the specified
configuration. Configuration commands and data
are encoded in the EEPROM as specified in the
‘Configuration By EEPROM’ section of this data
sheet, starting on page 25.
5.1 Pin Descriptions
RESET - Pin 18
BOOT
Reset Mode
1
EEPROM boot
0
Microcontroller boot
5.2 Reset Self-Tests
Microcontroller Boot
After RESET is released but before booting, a series of digital filter self-tests are run. Results are
Self-Test
Type
Pass
Code
Fail
Code
Program ROM
0x00000A
0x00000F
Data ROM
0x0000A0
0x0000F0
Program RAM
0x000A00
0x000F00
Data RAM
0x00A000
0x00F000
Execution Unit
0x0A0000
0x0F0000
DS639F1
When the BOOT pin is low after reset, the CS5378
enters an idle state waiting for a microcontroller to
write configuration commands and initialize filter
operation. Configuration commands and data are
written as specified in the ‘Configuration By Microcontroller’ section of this data sheet, starting on
page 30.
21
CS5378
CLK
PLL
32.768
MHz
Internal
Clocks
Clock Divider
and MCLK
Generator
PLL[2:0]
MCLK
Output
DSPCFG Register
Figure 12. Clock Generation Block Diagram
6. PLL AND CLOCK GENERATION
The CS5378 requires a 32.768 MHz master clock,
which can be supplied directly or from an internal
phase locked loop. This master clock is used to
generate an internal digital filter clock and an external modulator clock.
The internal PLL will lock to standard clock or
manchester encoded input signals. The input type
and input frequency are selected by the reset state
of the PLL mode select pins.
6.1 Pin Descriptions
CLK - Pin 17
Clock or PLL input, standard clock or manchester.
GPIO[4:6]:PLL[0:2] - Pins 5, 6, 7
PLL mode select, latched immediately after reset.
Weak (~100 kΩ) internal pull-ups default high, external 10 kΩ pull-downs required to set low.
A weak internal pull-up resistor (~100 kΩ) will
hold the PLL mode select pins high by default. To
force the pin low on reset, an external 10 kΩ pulldown resistor should be connected. Once the pin
state is latched following reset, the GPIO[4:6] pins
funtion without affecting PLL operation.
6.3 Synchronous Clocking
To guarantee synchronous measurements throughout a sensor network, a system clock should be distributed to arrive at all nodes in phase. The
distributed system clock can either be the full
32.768 MHz master clock, or the CS5378 PLL can
create a synchronous 32.768 MHz clock from a
slower clock. To ensure the generated clock remains synchronous with the network, the CS5378
PLL uses a phase/frequency detector architecture.
PLL[2:0]
PLL Mode
111
32.768 MHz clock input (PLL bypass).
6.2 PLL Mode Select
110
1.024 MHz clock input.
The CS5378 PLL operational mode and frequency
are selected immediately after reset based on the
state of the PLL[0:2] pins. On the rising edge of the
reset signal, the digital high or low state of the
PLL[0:2] pins is latched and used to program the
clock input type and frequency.
101
2.048 MHz clock input.
100
4.096 MHz clock input.
011
32.768 MHz clock input (PLL bypass).
010
1.024 MHz manchester input.
001
2.048 MHz manchester input.
000
4.096 MHz manchester input.
Table 5. PLL Mode Selections
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22
CS5378
6.4 Master Clock Jitter and Skew
Care must be taken to minimize jitter and skew on
the distributed system clock as both parameters affect measurement performance.
DS639F1
Jitter on the input clock causes jitter in the generated modulator clock, resulting in sample timing errors and increased noise.
Skew between input clocks from node to node creates a sample timing offset, resulting in systematic
measurement errors in a reconstructed signal.
23
CS5378
0
SYNC
1
MSYNC
Generator
Digital
Filter
0
1
MSYNC
Output
MSEN
Test Bit
Stream
TSYNC
Figure 13. Synchronization Block Diagram
7. SYNCHRONIZATION
The CS5378 has a dedicated SYNC input that
aligns the internal digital filter phase and generates
an external signal for synchronizing modulator analog sampling. By providing simultaneous rising
edges to the SYNC pins of multiple CS5378 devices, synchronous sampling across a network can be
guaranteed.
phase. Filter convolutions restart, and the next output word is available one full sample period later.
7.1 Pin Description
7.4
SYNC - Pin 19
The external MSYNC signal phase aligns modulator analog sampling when connected to the CS5371
MSYNC input. This ensures synchronous analog
sampling relative to MCLK.
Synchronization input, rising edge triggered.
7.2 MSYNC Generation
The SYNC signal rising edge is used to generate a
retimed synchronization signal, MSYNC. The
MSYNC signal reinitializes internal digital filter
phase and is driven onto the MSYNC output pin to
phase align modulator analog sampling.
The MSEN bit in the digital filter CONFIG register
(0x00) enables MSYNC generation. See “Modulator Interface” on page 36 for more information
about MSYNC.
7.3 Digital Filter Synchronization
The internal MSYNC signal resets the digital filter
state machine to establish a known digital filter
DS639F1
Repetitive synchronization is supported when
SYNC events occur at exactly the selected output
rate. In this case, re-synchronization will occur at
the start of a convolution cycle when the digital filter state machine is already reset.
Modulator Synchronization
Repetitive synchronization of the modulators is
supported when SYNC events occur at exactly the
selected output rate. In this case, re-synchronization always occurs at the start of analog sampling.
7.5 Test Bit Stream Synchronization
When the test bit stream generator is enabled, an
MSYNC signal can reset the internal data pointer.
This restarts the test bit stream from the first data
point to establish a known output signal phase.
The TSYNC bit in the digital filter TBSCFG register (0x2A) enables synchronization of the test bit
stream by MSYNC. When TSYNC is disabled, the
test bit stream phase is not affected by MSYNC.
24
CS5378
VD
SS:EECS
SCK
CS5378
MISO
MOSI
27
1
24
6
25
2
26
5
CS
3
8
7
WP VCC HOLD
SCK
AT25640
SO
SI
4
GND
Figure 14. EEPROM Configuration Block Diagram
8. CONFIGURATION BY EEPROM
After reset, the CS5378 reads the state of the
GPIO7:BOOT pin to determine a source for configuration commands. If BOOT is high, the
CS5378 initiates serial transactions to read configuration information from an external EEPROM.
8.1 Pin Descriptions
Pins required for EEPROM boot are listed here,
other serial pins are inactive.
SCK - Pin 24
Serial clock output, nominally 1.024 MHz.
MISO - Pin 25
Serial data input pin. Valid on rising edge of SCK,
transition on falling edge.
MOSI - Pin 26
Serial data output pin. Valid on rising edge of
SCK, transition on falling edge.
SS:EECS - Pin 27
EEPROM chip select output, active low.
to read configuration commands and data. 8-bit
SPI opcodes and 16-bit addresses are combined to
read back 8-bit configuration commands and 24-bit
configuration data.
System design should include a connection to the
configuration EEPROM for in-circuit reprogramming. The CS5378 serial pins tri-state when inactive to support external connections to the serial
bus.
8.3 EEPROM Organization
The boot EEPROM holds the 8-bit commands and
24-bit data required to initialize the CS5378 into an
operational state. Configuration information starts
at memory location 0x10, with addresses 0x00 to
0x0F free for use as manufacturing header information.
The first serial transaction reads a 1-byte command
from memory location 0x10 and then, depending
on the command type, reads multiple 3-byte data
words to complete the command. Command and
data reads continue until the ‘Filter Start’ command
is recognized.
8.2 EEPROM Hardware Interface
When booting from EEPROM the CS5378 actively
performs serial transactions, as shown in Figure 15,
DS639F1
25
CS5378
Instruction
Read
Opcode
Address
0x03
Definition
ADDR[15:0]
Read data beginning at the address given in ADDR.
Serial Read from EEPROM
READ
CMD
0x03
MOSI
2 BYTE
ADDR
ADDR
ADDR
DATA1 DATA2 DATA3
MISO
1 BYTE / 3 BYTE
DATA
SS:EECS
Cycle
1
2
3
4
5
6
7
8
MSB
6
5
4
3
2
1
LSB
6
5
4
3
2
1
LSB
SCK
MOSI
MISO
MSB
X
SS:EECS
Figure 15. EEPROM Serial Read Transactions
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26
CS5378
Write DF Register - 0x01
0000h
0010h
Mfg Header
8-bit Command
N x 24-bit Data
8-bit Command
N x 24-bit Data
1FFFh
EEPROM
Manufacturing
Information
EEPROM
Command and
Data Values
This EEPROM command writes a data value to the
specified digital filter register. Digital filter registers control hardware peripherals and filtering
functions. See “Digital Filter Registers” on page 71
for the bit definitions of the digital filter registers.
Sample Command:
Write digital filter register 0x00 with data value
0x060431. Then write 0x20 with data 0x000240.
...
01 00 00 00 06 04 31
Figure 16. 8 Kbyte EEPROM Memory Organization
01 00 00 20 00 02 40
Write FIR Coefficients - 0x02
The maximum number of bytes that will be written
for a single configuration is less than 2 KByte
(16 Kbit), including command overhead:
Memory Requirement
Digital Filter Registers (12)
FIR Coefficients (255+255)
IIR Coefficients (3+5)
‘Filter Start’ Command
Total Bytes
Bytes
84
1537
25
1
1647
This EEPROM command writes custom coefficients for the FIR1 and FIR2 filters. The first two
data words set the number of FIR1 and FIR2 coefficients to be written. The remaining data words are
the concatenated FIR1 and FIR2 coefficients.
A maximum of 255 coefficients can be written for
each FIR filter, though the available digital filter
computation cycles will limit their practical size.
See “FIR Filter” on page 44 for more information
about FIR filter coefficients.
Sample Command:
Write FIR1 coefficients 0x00022E, 0x000771 then
FIR2 coefficients 0xFFFFB9, 0xFFFE8D.
Table 6. Maximum EEPROM Configuration
02 00 00 02 00 00 02
00 02 2E 00 07 71 FF FF B9 FF FE 8D
Supported serial configuration EEPROMs are
SPI mode 0 (0,0) compatible, 16-bit addresses, 8bit data, larger than 2 KByte (16 KBit). ATMEL
AT25640, AT25128, or similar serial EEPROMs
are recommended.
8.4 EEPROM Configuration Commands
A summary of available EEPROM commands is
shown in Table 7.
DS639F1
Write IIR Coefficients - 0x03
This EEPROM command writes custom coefficients for the two stage IIR filter. The IIR architecture and number of coefficients is fixed, so eight
data words containing coefficient values always
immediately follow the command byte. The IIR coefficient write order is: a11, b10, b11, a21, a22,
b20, b21, and b22. See “IIR Filter” on page 52 for
more information about IIR filter coefficients.
27
CS5378
Sample Command:
Sample Command:
Write IIR1 coefficients 0x84BC9D, 0x7DA1B1,
0x825E4F, and IIR2 coefficients 0x83694F,
0x3CAD5F, 0x3E5104, 0x835DF8, 0x3E5104.
Select IIR1 and IIR2 3 Hz @ 500 SPS low-cut coefficients, with FIR1 and FIR2 linear phase highcut coefficients. Data word 0x002200.
03
04 00 22 00
84 BC 9D 7D A1 B1 82 5E 4F 83 69 4F
Filter Start - 0x07
3C AD 5F 3E 51 04 83 5D F8 3E 51 04
This EEPROM command initializes and starts the
digital filter. Measurement data becomes available
one full sample period after this command is issued. No data words are required for this EEPROM command.
Write ROM Coefficients - 0x04
This EEPROM command selects the on-chip coefficients for the FIR1, FIR2, IIR 1st order, and IIR
2nd order filters for use by the digital filter. One
data word is required to select which internal coefficient sets to use. See “Filter Coefficient Selection” on page 38 for information about selecting
on-chip FIR and IIR coefficient sets.
Name
CMD
8-bit
Sample Command:
07
DATA
24-bit
Description
NOP
00
-
WRITE DF REGISTER
01
REG
DATA
No Operation
WRITE FIR COEFFICIENTS
02
NUM FIR1
NUM FIR2
(FIR COEF)
Write Custom FIR Coefficients
WRITE IIR COEFFICIENTS
03
a11
b10
b11
a21
a22
b20
b21
b22
Write Custom IIR Coefficients
WRITE ROM COEFFICIENTS
04
COEF SEL
NOP
05
-
No Operation
NOP
06
-
No Operation
FILTER START
07
-
Start Digital Filter Operation
Write Digital Filter Register
Use On-Chip Coefficients
(DATA) indicates multiple words of this type are to be written.
Table 7. EEPROM Boot Configuration Commands
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28
CS5378
8.5 Example EEPROM Configuration
Table 8 shows an example EEPROM file for a minimal CS5378 configuration.
Addr
Data
00
00
01
02
Description
Addr
Data
21
02
00
22
40
00
23
01
03
00
24
00
04
00
25
00
05
00
26
2A
06
00
27
07
07
00
28
40
08
00
29
40
09
00
2A
01
0A
00
2B
00
Mfg header
0B
00
2C
00
0C
00
2D
2B
0D
00
2E
04
0E
00
2F
B0
0F
00
30
00
10
04
31
07
11
00
12
22
13
00
14
01
15
00
16
00
17
00
18
06
19
04
1A
31
1B
01
1C
00
1D
00
1E
20
1F
00
Write ROM Coefficients
Description
Write TBSCFG Register
Write TBSGAIN Register
Filter Start
Write CONFIG Register
Write FILTCFG Register
Table 8. Example EEPROM File
DS639F1
29
CS5378
Digital Filter
Command
Interpreter
SPI
Registers
Serial
Pin Logic
SS:EECS
SCK
MOSI
MISO
Figure 17. Serial Interface Block Diagram
9. CONFIGURATION BY MICROCONTROLLER
After reset, the CS5378 reads the state of the
GPIO7:BOOT pin to determine a source for configuration commands. If BOOT is low, the CS5378
receives configuration commands from a microcontroller.
9.1 Pin Descriptions
Pins required for microcontroller boot are listed
here, other serial pins are inactive.
SS:EECS - Pin 27
Slave select input pin, active low. Serial chip select
input from a microcontroller.
9.2 Microcontroller Hardware Interface
When booting from a microcontroller the CS5378
receives configuration commands and configuration data through serial transactions, as shown in
Figure 18. 8-bit SPI opcodes and 8-bit addresses
are combined to read and write 24-bit configuration
commands and data.
Microcontroller serial transactions require toggling
the SS:EECS pin as the CS5378 chip select and
writing a serial clock to the SCK input. Serial data
is input to the CS5378 on the MOSI pin, and output
on the MISO pin.
MOSI - Pin 26
9.3 Microcontroller Serial Transactions
Serial data input pin. Valid on rising edge of SCK,
transition on falling edge.
Microcontroller configuration commands are written to the digital filter through SPI registers. A 24bit command and two 24-bit data words can be
written to the SPI registers in any single serial
transaction. Some commands require additional
data words through additional serial transactions to
complete.
MISO - Pin 25
Serial data output pin. Valid on rising edge of
SCK, transition on falling edge. Open drain output
requiring a 10 kΩ pull-up resistor.
SCK - Pin 24
Serial clock input pin. Serial clock input from microcontroller, maximum 4.096 MHz.
DS639F1
9.3.1 SPI opcodes
A microcontroller communicates with the CS5378
serial port using standard 8-bit SPI opcodes and an
8-bit address. The standard SPI ‘Read’ and ‘Write’
opcodes are listed in Figure 18.
30
CS5378
Instruction
Opcode
Address
Definition
Write
0x02
ADDR[7:0]
Write SPI registers beginning at the address in ADDR.
Read
0x03
ADDR[7:0]
Read SPI registers beginning at the address in ADDR.
Microcontroller Write to SPI Registers
SS:EECS
MISO
0x02
ADDR
Data1
Data2
DataN
Data2
DataN
MOSI
Microcontroller Read from SPI Registers
SS:EECS
0x03
MISO
ADDR
Data1
MOSI
Cycle
1
2
3
4
5
6
7
8
MSB
6
5
4
3
2
1
LSB
6
5
4
3
2
1
LSB
SCK
MOSI
MISO
MSB
X
SS:EECS
Figure 18. Microcontroller Serial Transactions
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31
CS5378
9.3.2 SPI registers
The SPI registers are shown in Figure 19 and are
24-bit registers mapped into an 8-bit register space
as high, mid, and low bytes. See “SPI Registers” on
page 66 for the bit definitions of the SPI registers.
MOSI: 03 01 00
MISO: xx xx 12
5-byte read of SPIDAT1
MOSI: 03 06 00 00 00
MISO: xx xx 12 34 56
9.3.3 Serial transactions
A serial transaction to the SPI registers starts with
an SPI opcode, followed by an address, and then
some number of data bytes written or read starting
at that address.
Typical serial write transactions require sending
groups of 5, 8, or 11 total bytes to the SPICMD or
SPIDAT1 registers:
9.3.4 Multiple serial transactions
Some configuration commands require multiple serial transactions to complete. There must be a
small delay between transactions for the CS5378 to
process the incoming data. Two methods can be
used to ensure the CS5378 is ready to receive the
next configuration command.
1) Delay a fixed 1 ms period to guarantee enough
time for the command to be completed.
5-byte write to SPICMD
02 03 12 34 56
2) Verify the status of the E2DREQ bit by reading
the SPICTRL register. When low, the CS5378 is
ready for the next command.
5-byte write to SPIDAT1
02 06 12 34 56
8-byte write to SPICMD, SPIDAT1
9.3.5 Polling E2DREQ
One transaction type that can always be performed
no matter the delay from the previous configuration
command is reading E2DREQ in the mid-byte of
the SPICTRL register. A 3-byte read transaction.
02 03 12 34 56 AB CD EF
8-byte write to SPIDAT1, SPIDAT2
02 06 12 34 56 AB CD EF
11-byte write to SPICMD, SPIDAT1, SPIDAT2
MOSI: 03 01 00
02 03 12 34 56 AB CD EF 65 43 21
Typical serial read transactions require groups of 3
or 5 bytes, split between writing into MOSI and
reading from MISO.
3-byte read of mid-byte of SPICTRL
Name
MISO: xx xx 01 <- E2DREQ bit high
MISO: xx xx 00 <- E2DREQ bit low
The E2DREQ bit reads high while a serial transaction is being processed. When low, the digital filter
is ready to receive a new serial transaction.
Addr.
Type
# Bits
SPICTRL
00 - 02
R/W
8, 8, 8
SPI Control
Description
SPICMD
03 - 05
R/W
8, 8, 8
SPI Command
SPIDAT1
06 - 08
R/W
8, 8, 8
SPI Data 1
SPIDAT2
09 - 0B
R/W
8, 8, 8
SPI Data 2
Figure 19. SPI Registers
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32
CS5378
9.4 Microcontroller Configuration
Commands
Read DF Register - 0x02
A summary of available microcontroller configuration commands is listed in Table 9.
Write DF Register - 0x01
This configuration command writes a specified
digital filter register. Digital filter registers control
hardware peripherals and filtering functions. See
“Digital Filter Registers” on page 71 for the bit definitions of the digital filter registers.
This command reads a specified digital filter register. The register value is requested in the first serial
transaction, with the register value copied to
SPIDAT1 and read in a subsequent serial transaction.
Sample Command:
Read digital filter registers 0x00 and 0x20.
02 03 00 00 02 00 00 00
Delay 1 ms or poll E2DREQ
Sample Command:
MOSI: 03 06 00 00 00
Write digital filter register 0x00 with data value
0x060431. Then write 0x20 with data 0x000240.
02 03 00 00 02 00 00 20
02 03 00 00 01 00 00 00 06 04 31
Delay 1 ms or poll E2DREQ
Delay 1 ms or poll E2DREQ
MOSI: 03 06 00 00 00
02 03 00 00 01 00 00 20 00 02 40
MISO: xx xx 00 02 40
Delay 1 ms or poll E2DREQ
Name
MISO: xx xx 06 04 31
CMD
24-bit
DAT1
24-bit
DAT2
24-bit
Description
NOP
000000
-
-
WRITE DF REGISTER
000001
REG
DATA
Write Digital Filter Register
READ DF REGISTER
000002
REG
[DATA]
-
Read Digital Filter Register
WRITE FIR COEFFICIENTS
000003
NUM FIR1
(FIR COEF)
NUM FIR2
(FIR COEF)
Write Custom FIR Coefficients
WRITE IIR COEFFICIENTS
000004
a11
b11
a22
b21
b10
a21
b20
b22
Write Custom IIR Coefficients
WRITE ROM COEFFICIENTS
000005
COEF SEL
-
Use On-Chip Coefficients
NOP
000006
-
-
No Operation
NOP
000007
-
-
No Operation
No Operation
FILTER START
000008
-
-
Start Digital Filter Operation
FILTER STOP
000009
-
-
Stop Digital Filter Operation
[DATA] indicates data word returned from digital filter.
(DATA) indicates multiple words of this type are to be written.
Table 9. Microcontroller Boot Configuration Commands
DS639F1
33
CS5378
Write FIR Coefficients - 0x03
02 06 3C AD 5F 3E 51 04
This command writes custom coefficients for the
FIR1 and FIR2 filters. The first two data words set
the number of FIR1 and FIR2 coefficients to be
written. The remaining data words are the concatenated FIR1 and FIR2 coefficients.
Delay 1 ms or poll E2DREQ
A maximum of 255 coefficients can be written for
each FIR filter, though the available digital filter
computation cycles will limit their practical size.
See “FIR Filter” on page 44 for more information
about FIR filter coefficients.
Sample Command:
Write FIR1 coefficients 0x00022E, 0x000771 then
FIR2 coefficients 0xFFFFB9, 0xFFFE8D.
02 03 00 00 03 00 00 02 00 00 02
Delay 1 ms or poll E2DREQ
02 06 00 02 2E 00 07 71
Delay 1 ms or poll E2DREQ
02 06 83 5D F8 3E 51 04
Delay 1 ms or poll E2DREQ
Write ROM Coefficients - 0x05
This configuration command selects the on-chip
coefficients for FIR1, FIR2, IIR 1st order, and IIR
2nd order filters for use by the digital filter. One
data word is required to select which internal coefficient sets to use. See “Filter Coefficient Selection” on page 38 for information about selecting
on-chip FIR and IIR coefficient sets.
Sample Command:
Select IIR1 and IIR2 3 Hz @ 500 SPS low-cut coefficients, with FIR1 and FIR2 linear phase highcut coefficients. Data word 0x002200.
02 03 00 00 05 00 22 00
Delay 1 ms or poll E2DREQ
02 06 FF FF B9 FF FE 8D
Delay 1 ms or poll E2DREQ
Write IIR Coefficients - 0x04
This command writes custom coefficients for the
two stage IIR filter. The IIR architecture and number of coefficients is fixed, so eight coefficient values immediately follow this command. The IIR
coefficient write order is: a11, b10, b11, a21, a22,
b20, b21, and b22. See “IIR Filter” on page 52 for
more information about IIR filter coefficients.
Sample Command:
Write IIR1 coefficients 0x84BC9D, 0x7DA1B1,
0x825E4F, and IIR2 coefficients 0x83694F,
0x3CAD5F, 0x3E5104, 0x835DF8, 0x3E5104.
02 03 00 00 04 84 BC 9D 7D A1 B1
Filter Start - 0x08
This command initializes and starts the digital filter. Measurement data becomes available one full
sample period after this command is issued. No
data words are required for this command.
Sample Command:
02 03 00 00 08
Delay 1 ms or poll E2DREQ
Filter Stop - 0x09
This command disables the digital filter. Measurement data output stops immediately after this command is issued. No data words are required for this
command.
Sample Command:
Delay 1 ms or poll E2DREQ
02 03 00 00 09
02 06 82 5E 4F 83 69 4F
Delay 1 ms or poll E2DREQ
Delay 1 ms or poll E2DREQ
DS639F1
34
CS5378
9.5 Example Microcontroller Configuration
Table 10 shows an example microcontroller transactions for a minimal CS5378 configuration.
Transaction
SPI Data
Description
01
02 03 00 00 05 00 22 00
Write ROM coefficients
02
Delay 1ms or poll E2DREQ
03
02 03 00 00 01 00 00 00 06 04 31
04
Delay 1ms or poll E2DREQ
05
02 03 00 00 01 00 00 20 00 02 40
06
Delay 1ms or poll E2DREQ
07
02 03 00 00 01 00 00 2A 07 40 40
08
Delay 1ms or poll E2DREQ
09
02 03 00 00 01 00 00 2B 04 B0 00
10
Delay 1ms or poll E2DREQ
11
02 03 00 00 08
Write CONFIG Register
Write FILTCFG Register
Write TBSCFG Register
Write TBSGAIN Register
Filter Start
Table 10. Example Microcontroller Configuration
DS639F1
35
CS5378
MCLK
MSYNC
MCLK /
MSYNC
Generate
MDATA
MDI Input
MFLAG
512 kHz
CLK
SYNC
SINC
Filter
DC Offset
& Gain
Correction
FIR
Filters
IIR
Filter
Output to High Speed Serial Interface
Output Rate 4000 SPS ~ 1 SPS
Figure 20. Modulator Data Interface
10. MODULATOR INTERFACE
The CS5378 performs digital filtering for a ∆Σ type
modulator. Signals from the ∆Σ modulators are
connected through the modulator data interface
(MDI).
10.2 Modulator Clock Generation
10.1 Pin Descriptions
MCLK typically operates at 2.048 MHz unless analog low-power modes require a 1.024 MHz modulator clock.
MCLK - Pin 11
Modulator clock output. Nominally 2.048 MHz or
1.024 MHz.
MSYNC - Pin 12
Modulator synchronization signal output. Generated from the SYNC input.
The MCLK output is a low-jitter, low-skew modulator clock generated from the 32.768 MHz master
clock.
The MCLK rate is selected and the MCLK output
is enabled by bits in the digital filter CONFIG register (0x00). By default MCLK is disabled and
driven low.
10.3 Modulator Synchronization
MFLAG - Pin 14
The MSYNC output signal follows an input to the
SYNC pin. MSYNC phase aligns the modulator
sampling instant to guarantee synchronous analog
sampling across a measurement network.
Modulator flag input. Driven high when the modulator is unstable due to an analog over-range condition.
MSYNC is enabled by a bit in the CONFIG register
(0x00). By default SYNC inputs do not cause an
MSYNC output.
MDATA - Pin 13
Modulator data input, nominally 512 kbit/s.
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36
CS5378
10.4 Modulator Data Input
10.5 Modulator Flag Input
The MDATA input expects 1-bit ∆Σ data at a
512 kHz or 256 kHz rate. The input rate is selected
by a bit in the CONFIG register (0x00). By default,
MDATA is expected at 512 kHz.
A high MFLAG input signal indicates the ∆Σ modulator has become unstable due to an analog overrange input signal. Once the over-range signal is
reduced, the modulator recovers stability and the
MFLAG signal is cleared.
The MDATA input one’s density is designed for
full scale positive at 86% and full scale negative at
14%, with absolute maximum over-range capability to 93% and 7%. These raw ∆Σ inputs are decimated and filtered by the digital filter to create 24bit samples at the output rate.
DS639F1
The MFLAG input is mapped to a status bit in the
serial data output stream, and is associated with
each sample when written. See “Serial Data Interface” on page 58 for more information on the
MFLAG error bit in the serial data status byte.
37
CS5378
Modulator
Input
512 kHz
SINC Filter
FIR1
2 - 64000
DC Offset
& Gain
Correction
4
FIR2
IIR1
2
1st Order
IIR2
2nd Order
Output to High Speed Serial Data Interface
Output Rate 4000 SPS ~ 1 SPS
Figure 21. Digital Filter Stages
11. DIGITAL FILTER INITIALIZATION
The CS5378 digital filter consists of three multistage sections: a three stage SINC filter, a two stage
FIR filter, and a two stage IIR filter.
To initialize the digital filter, FIR and IIR coefficient sets are selected using configuration commands, and the FILTCFG register (0x20) is written
to select the output filter stage, the output word
rate, and the number of enabled channels. The digital filter clock rate is then selected by writing the
CONFIG register (0x00).
11.1 Filter Coefficient Selection
Selection of SINC filter coefficients is not required
as they are selected automatically based on the programmed output word rate.
Digital filter FIR and IIR coefficients are selected
using the ‘Write FIR Coefficients’ and ‘Write IIR
Coefficients’, or the ‘Write ROM Coefficients’
configuration commands. When writing the FIR
and IIR coefficients from ROM, a data word selects
an on-chip coefficient set for each filter stage. Figure 22 shows the format of the coefficient selection
DS639F1
word, and the available coefficient sets for each selection.
Characteristics of the on-chip digital filter coefficients are discussed in the ‘SINC Filter’, ‘FIR Filter’, and ‘IIR Filter’ sections of this data sheet.
11.2 Filter Configuration Options
Digital filter parameters are selected by bits in the
FILTCFG register (0x20), and the digital filter
clock rate is selected by bits in the CONFIG register (0x00).
11.2.1 Output Filter Stage
The digital filter can output data following any
stage in the filter chain. The output filter stage is
selected by the FSEL bits in the FILTCFG register.
Taking data from the SINC or FIR1 filter stages reduces the overall decimation of the filter chain and
increases the output rate, as discussed in the next
section. Taking data from FIR2, IIR1, IIR2, or IIR3
results in data at the selected rate.
38
CS5378
Bits
23:20
19:16
15:12
11:8
7:4
3:0
Selection
0000
0000
IIR2
IIR1
FIR2
FIR1
Bits 15:12
IIR2 Coefficients
Bits 11:8
IIR1 Coefficients
Bits 3:0
FIR1 Coefficients
0000
3 Hz @ 2000 SPS
0000
3 Hz @ 2000 SPS
0000
Linear Phase
0001
3 Hz @ 1000 SPS
0001
3 Hz @ 1000 SPS
0001
Minimum Phase
0010
3 Hz @ 500 SPS
0010
3 Hz @ 500 SPS
0011
3 Hz @ 333 SPS
0011
3 Hz @ 333 SPS
Bits 7:4
FIR2 Coefficients
0100
3 Hz @ 250 SPS
0100
3 Hz @ 250 SPS
0000
Linear Phase
0001
Minimum Phase
Figure 22. FIR and IIR Coefficient Set Selection Word
11.2.2 Output Word Rate
The CS5378 digital filter supports output word
rates (OWRs) between 4000 SPS and 1 SPS. The
output word rate is selected by the DEC bits in the
FILTCFG register.
When taking data directly from the SINC filter, the
decimation of the FIR1 and FIR2 stages is bypassed and the actual output word rate is multiplied
by a factor of eight compared with the register selection. When taking data directly from FIR1, the
decimation of the FIR2 stage is bypassed and the
actual output word rate is multiplied by a factor of
two. Data taken from the FIR2, IIR1, IIR2, or IIR3
filtering stages is output at the selected rate.
Computation Cycles
The minimum digital filter clock rate for a configuration depends on the computation cycles required
to complete digital filter convolutions at the selected output word rate. All configurations work for a
maximum digital filter clock, but lower clock rates
consume less power.
Standby Mode
The CS5378 can be placed in a low-power standby
mode by sending the ‘Filter Stop’ configuration
command and programming the digital filter clock
to 32 kHz. In this mode the digital filter idles, consuming minimal power until re-enabled by later
configuration commands.
11.2.3 Digital Filter Clock
The digital filter clock rate is programmable between 8.192 MHz and 32 kHz by bits in the CONFIG register.
DS639F1
39
CS5378
1-bit
∆−Σ
Input
4th order
sinc3
stage1
5
5th order
sinc1
8
4th order
sinc3
stage2
5
4th order
sinc2
stage1
2
4th order
sinc3
stage3
5
4th order
sinc2
stage2
2
5th order
sinc3
stage4
5
5th order
sinc2
stage3
2
5th order
sinc3
stage5
2
6th order
sinc2
stage4
2
6th order
sinc3
stage6
3
6th order
sinc3
stage7
2
24-bit
Output
Figure 23. SINC Filter Block Diagram
12. SINC FILTER
The SINC filter primary purpose is to attenuate outof-band noise components from the ∆Σ modulators. While doing so, they decimate 1-bit ∆Σ data
into lower frequency 24-bit data suitable for the
FIR and IIR filters.
The SINC filter has three cascaded sections,
SINC1, SINC2, and SINC3, which are each made
up of the smaller stages shown in Figure 23.
The selected output word rate in the FILTCFG register automatically determines the coefficients and
decimation ratios selected for the SINC filters.
12.1 SINC1 Filter
The first section is SINC1, a single stage 5th order
fixed decimate by 8 SINC filter. This SINC filter
decimates the incoming 1-bit ∆Σ bit stream from
the modulators down to a 64 kHz rate.
DS639F1
12.2 SINC2 Filter
The second section is SINC2, a multi-stage, variable order, variable decimation SINC filter. Depending on the selected output word rate in the
FILTCFG register, different cascaded SINC2 stages are enabled, as shown in Table 11.
12.3 SINC3 Filter
The last section is SINC3, a flexible multi-stage
variable order, variable decimation SINC filter.
Depending on the selected output word rate in the
FILTCFG register, different SINC3 stages are enabled, as shown in Table 11.
12.4 SINC Filter Synchronization
The SINC filter is synchronized to the external system by the MSYNC signal, which is generated
from the SYNC input. The MSYNC signal sets a
reference time (time 0) for all filter operations, and
the SINC filter is restarted to phase align with this
reference time.
40
CS5378
SINC1 – Single stage, fixed decimate by 8
5th order decimate by 8, 36 coefficients
SINC2 – Multi-stage, variable decimation
Stage
Stage
Stage
Stage
1:
2:
3:
4:
4th
4th
5th
6th
order
order
order
order
decimate
decimate
decimate
decimate
by
by
by
by
2,
2,
2,
2,
5
5
6
7
coefficients
coefficients
coefficients
coefficients
SINC3 – Multi-stage, variable decimation
Stage
Stage
Stage
Stage
Stage
Stage
Stage
1:
2:
3:
4:
5:
6:
7:
4th
4th
4th
5th
5th
6th
6th
order
order
order
order
order
order
order
decimate
decimate
decimate
decimate
decimate
decimate
decimate
by
by
by
by
by
by
by
5,
5,
5,
5,
2,
3,
2,
17
17
17
21
6
13
7
coefficients
coefficients
coefficients
coefficients
coefficients
coefficients
coefficients
Figure 24. SINC Filter Stages
SINC filters
FIR2
Output
Word
Rate
4000
2000
1000
500
333
250
200
125
100
50
40
25
20
10
5
1
DEC Bit
Setting
0111
0110
0101
0100
0011
0010
0001
0000
1111
1110
1101
1100
1011
1010
1001
1000
SINC1
Decimation
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
SINC2
Decimation
2
4
8
16
8
16
4
16
4
8
4
16
4
8
16
16
SINC2
Stages
4
3,4
2,3,4
1,2,3,4
2,3,4
1,2,3,4
3,4
1,2,3,4
3,4
2,3,4
3,4
1,2,3,4
3,4
2,3,4
1,2,3,4
1,2,3,4
SINC3
Decimation
3
2
10
4
20
20
50
20
100
100
100
500
SINC3
Stages
6
7
4,7
5,7
3,5,7
3,5,7
3,4,7
3,5,7
2,3,5,7
2,3,5,7
2,3,5,7
1,2,3,5,7
Table 11. SINC Filter Configurations
DS639F1
41
CS5378
Filter Type
System Function
SINC1
5th order decimate by 8
36 coefficients
⎛ 1 − z −8 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
⎝1− z ⎠
Filter Type
System Function
SINC2 (Stage 1)
SINC2 (Stage 2)
4th order decimate by 2
5 coefficients
⎛ 1 − z −2 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
⎝1− z ⎠
4
h0
h1
h2
h3
h4
=
=
=
=
=
1
4
6
4
1
SINC2 (Stage 3)
5th order decimate by 2
6 coefficients
⎛ 1 − z −2 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
⎝1− z ⎠
5
h0
h1
h2
h3
h4
h5
=
=
=
=
=
=
1
5
10
10
5
1
SINC2 (Stage 4)
6th order decimate by 2
7 coefficients
⎛ 1 − z −2 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
⎝1− z ⎠
6
h0
h1
h2
h3
h4
h5
h6
=
=
=
=
=
=
=
1
6
15
20
15
6
1
5
Filter Coefficients
h0
h1
h2
h3
h4
h5
h6
h7
h8
h9
h10
h11
h12
h13
h14
h15
h16
h17
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
1
5
15
35
70
126
210
330
490
690
926
1190
1470
1750
2010
2226
2380
2460
h18
h19
h20
h21
h22
h23
h24
h25
h26
h27
h28
h29
h30
h31
h32
h33
h34
h35
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
2460
2380
2226
2010
1750
1470
1190
926
690
490
330
210
126
70
35
15
5
1
Filter Coefficients
Table 12. SINC1 and SINC2 Filter Coefficients
DS639F1
42
CS5378
Filter Type
System Function
Filter Coefficients
SINC3 (Stage 1)
SINC3 (Stage 2)
SINC3 (Stage 3)
4th order decimate by 5
17 coefficients
⎛ 1 − z −5 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
⎝1− z ⎠
4
h0
h1
h2
h3
h4
h5
h6
h7
h8
SINC3 (Stage 4)
5th order decimate by 5
21 coefficients
⎛ 1 − z −5 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
1
z
−
⎠
⎝
5
h0 = 1
h1 = 5
h2 = 15
h3 = 35
h4 = 70
h5 = 121
h6 = 185
h7 = 255
h8 = 320
h9 = 365
h10 = 381
SINC3 (Stage 5)
5th order decimate by 2
6 coefficients
⎛ 1 − z −2 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
1
z
−
⎠
⎝
5
h0
h1
h2
h3
h4
h5
SINC3 (Stage 6)
6th order decimate by 3
13 coefficients
⎛ 1 − z −3 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
1
z
−
⎠
⎝
6
h0
h1
h2
h3
h4
h5
h6
SINC3 (Stage 7)
6th order decimate by 2
7 coefficients
⎛ 1 − z −2 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
⎝1− z ⎠
6
h0
h1
h2
h3
h4
h5
h6
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
1
4
10
20
35
52
68
80
85
h9
h10
h11
h12
h13
h14
h15
h16
=
=
=
=
=
=
=
=
h11 =
h12 =
h13 =
h14 =
h15 =
h16 =
h17 =
h18 =
h19 =
h20 =
80
68
52
35
20
10
4
1
365
320
255
185
121
70
35
15
5
1
1
5
10
10
5
1
1
6
21
50
90
126
141
h7
h8
h9
h10
h11
h12
=
=
=
=
=
=
126
90
50
21
6
1
1
6
15
20
15
6
1
Table 13. SINC3 Filter Coefficients
DS639F1
43
CS5378
FIR1 Filter - decimate by 4
FIR2 Filter - decimate by 2
Figure 25. FIR Filter Block Diagram
13. FIR FILTER
The finite impulse response (FIR) filter block consists of two cascaded stages, FIR1 and FIR2. It
compensates for SINC filter droop and creates a
low-pass corner to block aliased components of the
input signal.
On-chip linear phase or minimum phase coefficients can be selected using a configuration command, or the coefficients can be programmed for a
custom filter response.
13.1 FIR1 Filter
The FIR1 filter stage has a decimate by four architecture. It compensates for SINC filter droop and
flattens the magnitude response of the pass band.
The on-chip linear and minimum phase coefficient
sets are 48-tap, with a maximum 255 programmable coefficients. All coefficients are normalized to
24-bit two’s complement full scale, 0x7FFFFF.
The characteristic equation for FIR1 is a convolution of the input values, X(n), and the filter coefficients, h(k), to produce an output value, Y.
Y = [h(k)*X(n-k)] + [h(k+1)*X(n-(k+1))] + ...
DS639F1
13.2 FIR2 Filter
The FIR2 filter stage has a decimate by two architecture. It creates a low-pass brick wall filter to
block aliased components of the input signal.
The on-chip linear and minimum phase coefficient
sets are 126-tap, with a maximum 255 programmable coefficients. All coefficients are normalized to
24-bit two’s complement full scale, 0x7FFFFF.
The characteristic equation for FIR2 is a convolution of the input values, X(n), and the filter coefficients, h(k), to produce an output value, Y.
Y = [h(k)*X(n-k)] + [h(k+1)*X(n-(k+1))] + ...
13.3 On-Chip FIR Coefficients
Two sets of on-chip coefficients, linear phase and
minimum phase, are available for FIR1 and FIR2.
Performance of the on-chip coefficient sets is very
good, with excellent ripple and stop band characteristics as described in Figure 26 and Table 14.
Which on-chip coefficient set to use is selected by
a data word following the ‘Write ROM Coefficients’ configuration command. See “Filter Coefficient Selection” on page 38 for information about
selecting on-chip coefficient sets.
44
CS5378
13.4 Programmable FIR Coefficients
A maximum of 255 + 255 coefficients can be programmed into FIR1 and FIR2 to create a custom
filter response. The total number of coefficients for
the FIR filter is fundamentally limited by the available computation cycles in the digital filter, which
itself is determined by the digital filter clock rate.
Custom filter sets should normalize the maximum
coefficient value to 24-bit two’s complement full
scale, 0x7FFFFF, and scale all other coefficients
accordingly. To maintain maximum internal dynamic range, the CS5378 FIR filter performs double precision calculations with an automatic gain
correction to scale the final output.
DS639F1
Custom FIR coefficients are uploaded using the
‘Write FIR Coefficients’ configuration command.
See “EEPROM Configuration Commands” on
page 27 or “Microcontroller Configuration Commands” on page 33 for information about writing
custom FIR coefficients.
13.5 FIR Filter Synchronization
The FIR1 and FIR2 filters are synchronized to the
external system by the MSYNC signal, which is
generated from the SYNC input. The MSYNC signal sets a reference time (time 0) for all filter operations, and the FIR filters are restarted to phase
align with this reference time.
45
CS5378
FIR1 – Single stage, fixed decimate by 4
Coefficient set 0: linear phase decimate by 4, 48 coefficients
Coefficient set 1: minimum phase decimate by 4, 48 coefficients
SINC droop compensation filter
FIR2 – Single stage, fixed decimate by 2
Coefficient set 0: linear phase decimate by 2, 126 coefficients
Coefficient set 1: minimum phase decimate by 2, 126 coefficients
Brick wall low-pass filter, flat to 40% fs
Combined SINC + FIR digital filter specifications
Passband ripple less than +/- 0.01 dB below 40% fs
Transition band -3 dB frequency at 42.89% fs
Stopband attenuation greater than 130 dB above 50% fs
Figure 26. FIR Filter Stages
SINC + FIR filters
FIR2
Output
Word
Rate
4000
2000
1000
500
333
250
200
125
100
50
40
25
20
10
5
1
SINC
Decimation
16
32
64
128
192
256
320
512
640
1280
1600
2560
3200
6400
12800
64000
FIR1
Decimation
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
FIR2
Decimation
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Total
Decimation
128
256
512
1024
1536
2048
2560
4096
5120
10240
12800
20480
25600
51200
102400
512000
Passband
Ripple
(± dB)
0.0042
0.0045
0.0040
0.0041
0.0080
0.0064
0.0043
0.0046
0.0040
0.0040
0.0040
0.0040
0.0036
0.0036
0.0036
0.0029
Stopband
Attenuation
(dB)
130.38
130.38
130.42
130.42
130.45
130.43
130.44
130.42
130.43
130.43
130.44
132.98
130.43
130.43
130.43
134.31
Table 14. FIR Filter Characteristics
DS639F1
46
CS5378
Individual filter stage group delay (no IIR)
Decimation
Ratios
8
SINC1
SINC2
Stage 4
Stages 3,4
Stages 2,3,4
Stages 1,2,3,4
Number of
Coefficients
36
Group Delay
(Input Rate)
17.5
2
2,2
2,2,2
2,2,2,2
7
6,7
5,6,7
5,5,6,7
3.0
8.5
19.0
40.0
2
3
2,2
5,2
5,2,2
5,5,2
5,5,2,2
5,5,5,2,2
7
13
6,7
21,7
17,6,7
17,21,7
17,17,6,7
17,17,17,6,7
3.0
6.0
8.5
25.0
50.5
133.0
260.5
1310.5
Coefficient Set 0
Coefficient Set 1
4
4
48
48
23.5
See Figure
Coefficient Set 0
Coefficient Set 1
2
2
126
126
62.5
See Figure
SINC3
Stage 7
Stage 6
Stages 5,7
Stages 4,7
Stages 3,5,7
Stages 3,4,7
Stages 2,3,5,7
Stages 1,2,3,5,7
FIR1
FIR2
Cumulative linear phase group delay (no IIR)
FIR2
Output
Word
Rate
4000
2000
1000
500
333
250
200
125
100
50
40
25
20
10
5
1
SINC Output
Group Delay
(SINC Filter
Input Rate)
41.5
85.5
169.5
337.5
553.5
721.5
885.5
1425.5
1701.5
3401.5
4341.5
6801.5
8421.5
16841.5
33681.5
168081.5
FIR1 Output
Group Delay
(SINC Filter
Input Rate)
417.5
837.5
1673.5
3345.5
5065.5
6737.5
8405.5
13457.5
16741.5
33481.5
41941.5
66961.5
83621.5
167241.5
334481.5
1672081.5
FIR2 Output
Group Delay
(SINC Filter
Input Rate)
4417.5
8837.5
17673.5
35345.5
53065.5
70737.5
88405.5
141457.5
176741.5
353481.5
441941.5
706961.5
883621.5
1767241.5
3534481.5
17672081.5
FIR2 Output
Group Delay
(FIR2 Output
Word Rate)
34.5117
34.5215
34.5186
34.5171
34.5479
34.5398
34.5334
34.5355
34.5198
34.5197
34.5267
34.5196
34.5165
34.5164
34.5164
34.5158
Table 15. SINC + FIR Group Delay
DS639F1
47
CS5378
Minimum phase group delay
FIR1
Minimum
Phase Group
Delay
(Normalized
frequency)
FIR2
Minimum
Phase Group
Delay
(Normalized
frequency)
Table 16. Minimum Phase Group Delay
DS639F1
48
CS5378
Filter Type
FIR1 (Coefficient set 0)
Low pass, SINC compensation
Linear phase decimate by 4
48 coefficients
FIR1 (Coefficient set 1)
Low pass, SINC compensation
Minimum phase decimate by 4
48 coefficients
Filter Coefficients
(normalized 24-bit)
h0 = 558
h24
h1 = 1905
h25
h26
h2 = 3834
h3 = 5118
h27
h28
h4 = 365
h5 = -14518
h29
h6 = -39787
h30
h31
h7 = -67365
h8 = -69909
h32
h33
h9 = -19450
h10 = 97434
h34
h11 = 258881
h35
h36
h12 = 375562
h13 = 332367
h37
h38
h14 = 39864
h15 = -496361
h39
h16 = -1084130
h40
h41
h17 = -1392827
h18 = -1053303
h42
h43
h19 = 189436
h20 = 2266428
h44
h21 = 4768946
h45
h46
h22 = 7042723
h23 = 8388607
h47
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
8388607
7042723
4768946
2266428
189436
-1053303
-1392827
-1084130
-496361
39864
332367
375562
258881
97434
-19450
-69909
-67365
-39787
-14518
365
5118
3834
1905
558
h0
h1
h2
h3
h4
h5
h6
h7
h8
h9
h10
h11
h12
h13
h14
h15
h16
h17
h18
h19
h20
h21
h22
h23
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
555919
-165441
-581479
-617500
-388985
-99112
114761
186557
141374
58582
-12664
-42821
-35055
-16792
367
7929
5926
2892
23
-1164
-538
-238
18
113
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
3337
22258
88284
266742
655747
1371455
2502684
4031988
5783129
7396359
8388607
8325707
6988887
4531706
1507479
-1319126
-3207750
-3736028
-2980701
-1421498
237307
1373654
1711919
1322371
h24
h25
h26
h27
h28
h29
h30
h31
h32
h33
h34
h35
h36
h37
h38
h39
h40
h41
h42
h43
h44
h45
h46
h47
Figure 27. FIR1 Coefficients
DS639F1
49
CS5378
Filter Type
Filter Coefficients
(normalized 24-bit)
FIR2 (Coefficient set 0)
Low pass, passband to 40% fs
Linear phase decimate by 2
126 coefficients
h0
h1
h2
h3
h4
h5
h6
h7
h8
h9
h10
h11
h12
h13
h14
h15
h16
h17
h18
h19
h20
h21
h22
h23
h24
h25
h26
h27
h28
h29
h30
h31
h32
h33
h34
h35
h36
h37
h38
h39
h40
h41
h42
h43
h44
h45
h46
h47
h48
h49
h50
h51
h52
h53
h54
h55
h56
h57
h58
h59
h60
h61
h62
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
-71
-371
-870
-986
34
1786
2291
291
-2036
-943
2985
3784
-1458
-5808
-1007
7756
5935
-7135
-11691
3531
17500
4388
-20661
-15960
18930
29808
-9795
-42573
-7745
49994
33021
-47092
-62651
29702
90744
4436
-109189
-54172
109009
114154
-81993
-174452
22850
221211
68863
-238025
-187141
208018
318763
-116005
-443272
-49958
533334
298975
-553873
-642475
454990
1113788
-137179
-1854336
-766230
3875315
8388607
h63
h64
h65
h66
h67
h68
h69
h70
h71
h72
h73
h74
h75
h76
h77
h78
h79
h80
h81
h82
h83
h84
h85
h86
h87
h88
h89
h90
h91
h92
h93
h94
h95
h96
h97
h98
h99
h100
h101
h102
h103
h104
h105
h106
h107
h108
h109
h110
h111
h112
h113
h114
h115
h116
h117
h118
h119
h120
h121
h122
h123
h124
h125
= 8388607
= 3875315
= -766230
= -1854336
= -137179
= 1113788
= 454990
= -642475
= -553873
= 298975
= 533334
= -49958
= -443272
= -116005
= 318763
= 208018
= -187141
= -238025
= 68863
= 221211
= 22850
= -174452
= -81993
= 114154
= 109009
= -54172
= -109189
= 4436
= 90744
= 29702
= -62651
= -47092
= 33021
= 49994
= -7745
= -42573
= -9795
= 29808
= 18930
= -15960
= -20661
= 4388
= 17500
= 3531
= -11691
= -7135
= 5935
= 7756
= -1007
= -5808
= -1458
= 3784
= 2985
= -943
= -2036
= 291
= 2291
= 1786
= 34
= -986
= -870
= -371
= -71
Figure 28. FIR2 Linear Phase Coefficients
DS639F1
50
CS5378
Filter Type
Filter Coefficients
(normalized 24-bit)
FIR2 (Coefficient set 1)
Low pass, passband to 40% fs
Minimum phase decimate by 2
126 coefficients
h0
h1
h2
h3
h4
h5
h6
h7
h8
h9
h10
h11
h12
h13
h14
h15
h16
h17
h18
h19
h20
h21
h22
h23
h24
h25
h26
h27
h28
h29
h30
h31
h32
h33
h34
h35
h36
h37
h38
h39
h40
h41
h42
h43
h44
h45
h46
h47
h48
h49
h50
h51
h52
h53
h54
h55
h56
h57
h58
h59
h60
h61
h62
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
4019
43275
235427
848528
2240207
4525758
7077833
8388607
6885673
2483461
-2538963
-4800543
-2761696
1426109
3624338
1820814
-1695825
-2885148
-605252
2135021
1974197
-630111
-2168177
-750147
1516192
1550127
-508445
-1686937
-437822
1308705
1069556
-657282
-1301014
-30654
1173754
579643
-803111
-895851
328399
962522
124678
-820948
-466657
545674
652827
-220448
-680495
-80886
578844
306445
-395302
-431004
181900
454403
15856
-395525
-166123
284099
253485
-152407
-277888
28526
250843
h63
h64
h65
h66
h67
h68
h69
h70
h71
h72
h73
h74
h75
h76
h77
h78
h79
h80
h81
h82
h83
h84
h85
h86
h87
h88
h89
h90
h91
h92
h93
h94
h95
h96
h97
h98
h99
h100
h101
h102
h103
h104
h105
h106
h107
h108
h109
h110
h111
h112
h113
h114
h115
h116
h117
h118
h119
h120
h121
h122
h123
h124
h125
= 67863
= -190800
= -128546
= 114197
= 147750
= -46352
= -143269
= -13290
= 114721
= 51933
= -75952
= -68746
= 38171
= 68492
= -7856
= -57526
= -12540
= 41717
= 23334
= -25516
= -26409
= 11717
= 24246
= -1620
= -19248
= -4610
= 13356
= 7526
= -7887
= -8016
= 3559
= 7023
= -598
= -5350
= -1097
= 3579
= 1806
= -2058
= -1859
= 936
= 1558
= -224
= -1129
= -152
= 718
= 290
= -395
= -290
= 178
= 227
= -53
= -151
= -5
= 86
= 23
= -42
= -22
= 17
= 14
= -5
= -7
= 1
= 3
Figure 29. FIR2 Minimum Phase Coefficients
DS639F1
51
CS5378
1st Order IIR1
2nd Order IIR2
b10
b20
Z-1
Z-1
-a11
b11
-a21
b21
Z-1
3rd Order IIR3 implemented by
running both IIR1 and IIR2 stages
-a22
b22
Figure 30. IIR Filter Block Diagram
14. IIR FILTER
The infinite impulse response (IIR) filter block
consists of two cascaded stages, IIR1 and IIR2. It
creates a high-pass corner to block very low-frequency and DC components of the input signal.
The characteristic equations for the 1st order IIR
include an input value, X, an output value, Y, and
two intermediate values, W1 and W2, separated by
a delay element (z-1).
On-chip IIR1 and IIR2 coefficients can be selected
using a configuration command, or the coefficients
can be programmed for a custom filter response.
W2 = W1
14.1 IIR Architecture
The architecture of the IIR filter is automatically
determined when the output filter stage is selected
in the FILTCFG register. Selecting the 1st order
IIR1 filter bypasses the 2nd order stage, while selecting the 2nd order IIR2 filter bypasses the 1st order stage. Selection of the 3rd order IIR3 filter
enables both the 1st and 2nd order stages.
14.2 IIR1 Filter
The 1st order IIR filter stage is a direct form filter
with three coefficients: a11, b10, and b11. Coefficients of a 1st order IIR are inherently normalized
to one, and should be scaled to 24-bit two’s complement full scale, 0x7FFFFF.
DS639F1
W1 = X + (-a11 * W2)
Y = (W1 * b10) + (W2 * b11)
14.3 IIR2 Filter
The 2nd order IIR filter stage is a direct form filter
with five coefficients: a21, a22, b20, b21, and b22.
Coefficients of a 2nd order IIR are inherently normalized to two, and should be scaled to 24-bit
two’s complement full scale, 0x7FFFFF. Normalization effectively divides the 2nd order coefficients in half relative to the input, and requires
modification of the characteristic equations.
The characteristic equations for the 2nd order IIR
include an input value, X, an output value, Y, and
three intermediate values, W3, W4, and W5, each
separated by a delay element (z-1). The following
52
CS5378
characteristic equations model the operation of the
2nd order IIR filter with unnormalized coefficients.
W5 = W4
W4 = W3
Which on-chip coefficient set to use is selected by
a data word following the ‘Write ROM Coefficients’ configuration command. See “Filter Coefficient Selection” on page 38 for information about
selecting on-chip coefficient sets.
W3 = X + (-a21 * W4) + (-a22 * W5)
Y = (W3 * b20) + (W4 * b21) + (W5 * b22)
14.6 Programmable IIR Coefficients
Internally, the CS5378 uses normalized coefficients to perform the 2nd order IIR filter calculation, which changes the algorithm slightly. The
following characteristic equations model the operation of the 2nd order IIR filter when using normalized coefficients.
A maximum of 3 + 5 coefficients can be programmed into IIR1 and IIR2 to create a custom filter response. Custom filter sets should normalize
the coefficients to 24-bit two’s complement full
scale, 0x7FFFFF. To maintain maximum internal
dynamic range, the CS5378 IIR filter performs
double precision calculations with an automatic
gain correction to scale the final output.
W5 = W4
W4 = W3
W3 = 2 * [(X / 2) + (-a21 * W4) + (-a22 * W5)]
Y = 2 * [(W3 * b20) + (W4 * b21) + (W5 * b22)]
14.4 IIR3 Filter
The 3rd order IIR filter is implemented by running
both the 1st order and 2nd order IIR filter stages. It
can be modeled by cascading the characteristic
equations of the 1st order and 2nd order IIR stages.
14.5 On-Chip IIR Coefficients
Five sets of on-chip coefficients are available for
IIR1 and IIR2, each providing a 3 Hz high-pass
Butterworth response at different output word
rates. Characteristics of the on-chip coefficient sets
are described in Figure 31 and Table 16.
DS639F1
Custom IIR coefficients are uploaded using the
‘Write IIR Coefficients’ configuration command.
See “EEPROM Configuration Commands” on
page 27 or “Microcontroller Configuration Commands” on page 33 for information about writing
custom IIR coefficients.
14.7 IIR Filter Synchronization
The IIR filter is not synchronized to the external
system directly, only indirectly through the synchronization of the SINC and FIR filters. Because
IIR filters have ‘infinite’ memory, a discontinuity
in the input data stream from a synchronization
event can require significant time to settle out. The
exact settling time depends on the size of the discontinuity and the filter coefficient characteristics.
53
CS5378
IIR1 – Single stage, no decimation
1st order no decimation, 3 coefficients
Coefficient
Coefficient
Coefficient
Coefficient
Coefficient
set
set
set
set
set
0:
1:
2:
3:
4:
high-pass,
high-pass,
high-pass,
high-pass,
high-pass,
corner
corner
corner
corner
corner
0.15%
0.30%
0.60%
0.90%
1.20%
fs
fs
fs
fs
fs
(3
(3
(3
(3
(3
Hz
Hz
Hz
Hz
Hz
at
at
at
at
at
2000 SPS)
1000 SPS)
500 SPS)
333 SPS)
250 SPS)
fs
fs
fs
fs
fs
(3
(3
(3
(3
(3
Hz
Hz
Hz
Hz
Hz
at
at
at
at
at
2000 SPS)
1000 SPS)
500 SPS)
333 SPS)
250 SPS)
IIR2 – Single stage, no decimation
2nd order no decimation, 5 coefficients
Coefficient
Coefficient
Coefficient
Coefficient
Coefficient
set
set
set
set
set
0:
1:
2:
3:
4:
high-pass,
high-pass,
high-pass,
high-pass,
high-pass,
corner
corner
corner
corner
corner
0.15%
0.30%
0.60%
0.90%
1.20%
IIR3 – Two stage, no decimation
3rd order no decimation, 8 coefficients
(Combined IIR1 and IIR2 filter responses)
Coefficient
Coefficient
Coefficient
Coefficient
Coefficient
set
set
set
set
set
0,0:
1,1:
2,2:
3,3:
4,4:
high-pass,
high-pass,
high-pass,
high-pass,
high-pass,
corner
corner
corner
corner
corner
0.20%
0.41%
0.82%
1.22%
1.63%
fs
fs
fs
fs
fs
(4
(4
(4
(4
(4
Hz
Hz
Hz
Hz
Hz
at
at
at
at
at
2000 SPS)
1000 SPS)
500 SPS)
333 SPS)
250 SPS)
Figure 31. IIR Filter Stages
IIR filters
IIR1 Coeff
Selection
0
1
2
3
4
IIR1
Corner
Frequency
0.15% fs
0.30% fs
0.60% fs
0.90% fs
1.20% fs
IIR2 Coeff
Selection
0
1
2
3
4
IIR2
Corner
Frequency
0.15% fs
0.30% fs
0.60% fs
0.90% fs
1.20% fs
IIR3 Coeff
Selection
0,0
1,1
2,2
3,3
4,4
IIR3
Corner
Frequency
0.2041% fs
0.4074% fs
0.8152% fs
1.2222% fs
1.6293% fs
Table 16. IIR Filter Characteristics
DS639F1
54
CS5378
Filter Type
System Function
Filter Coefficients
(normalized 24-bit)
a11 = -8309916
b10 = 8349262
b11 = -8349262
IIR1 (Coefficient set 0)
1st order, high pass
Corner at 0.15% fs
3 coefficients
⎛ b + b z −1 ⎞
H ( z ) = ⎜⎜ 10 11 −1 ⎟⎟
⎝ 1 + a11 z ⎠
IIR1 (Coefficient set 1)
1st order, high pass
Corner at 0.30% fs
3 coefficients
⎛ b + b z −1 ⎞
H ( z ) = ⎜⎜ 10 11 −1 ⎟⎟
⎝ 1 + a11 z ⎠
a11 = -8231957
b10 = 8310282
b11 = -8310282
IIR1 (Coefficient set 2)
1st order, high pass
Corner at 0.60% fs
3 coefficients
⎛ b + b z −1 ⎞
H ( z ) = ⎜⎜ 10 11 −1 ⎟⎟
⎝ 1 + a11 z ⎠
a11 = -8078179
b10 = 8233393
b11 = -8233393
IIR1 (Coefficient set 3)
1st order, high pass
Corner at 0.90% fs
3 coefficients
⎛ b + b z −1 ⎞
H ( z ) = ⎜⎜ 10 11 −1 ⎟⎟
⎝ 1 + a11 z ⎠
a11 = -7927166
b10 = 8157887
b11 = -8157887
IIR1 (Coefficient set 4)
1st order, high pass
Corner at 1.20% fs
3 coefficients
⎛ b10 + b11 z −1 ⎞
⎟
H ( z ) = ⎜⎜
−1 ⎟
⎝ 1 + a11 z ⎠
a11 = -7778820
b10 = 8083714
b11 = -8083714
Filter Type
System Function
IIR2 (Coefficient set 0)
2nd order, high pass
Corner at 0.15% fs
5 coefficients
⎛ b20 + b21 z −1 + b22 z −1 ⎞
⎟
H ( z ) = ⎜⎜
−1
−1 ⎟
+
+
1
a
z
a
z
21
22
⎝
⎠
Filter Coefficients
(normalized 24-bit)
a21 = -8332704
a22 = 4138771
b20 = 4166445
b21 = -8332890
b22 = 4166445
IIR2 (Coefficient set 1)
2nd order, high pass
Corner at 0.30% fs
5 coefficients
⎛ b + b21 z −1 + b22 z −1 ⎞
⎟
H ( z ) = ⎜⎜ 20
−1
−1 ⎟
⎝ 1 + a 21 z + a 22 z ⎠
a21
a22
b20
b21
b22
=
=
=
=
=
-8276806
4083972
4138770
-8277540
4138770
IIR2 (Coefficient set 2)
2nd order, high pass
Corner at 0.60% fs
5 coefficients
⎛ b + b21 z −1 + b22 z −1 ⎞
⎟
H ( z ) = ⎜⎜ 20
−1
−1 ⎟
+
+
1
a
z
a
z
21
22
⎝
⎠
a21
a22
b20
b21
b22
=
=
=
=
=
-8165041
3976543
4083972
-8167944
4083972
IIR2 (Coefficient set 3)
2nd Order, high pass
Corner at 0.90% fs
5 coefficients
⎛ b + b21 z −1 + b22 z −1 ⎞
⎟
H ( z ) = ⎜⎜ 20
−1
−1 ⎟
⎝ 1 + a 21 z + a 22 z ⎠
a21
a22
b20
b21
b22
=
=
=
=
=
-8053350
3871939
4029898
-8059796
4029898
IIR2 (Coefficient set 4)
2nd order, high pass
Corner at 1.20% fs
5 coefficients
⎛ b + b21 z −1 + b22 z −1 ⎞
⎟
H ( z ) = ⎜⎜ 20
−1
−1 ⎟
+
+
1
a
z
a
z
21
22
⎝
⎠
a21
a22
b20
b21
b22
=
=
=
=
=
-7941764
3770088
3976539
-7953078
3976539
Table 17. IIR Filter Coefficients
DS639F1
55
CS5378
MDI Input
512 kHz
Gain
Correction
SINC
Filter
FIR
Filters
IIR
Filter
Output to High Speed Serial Data Port (SD Port)
Output Rate 4000 SPS ~ 1 SPS
Offset
Correction
Offset
Calibration
Figure 32. Gain and Offset Correction
15. GAIN AND OFFSET CORRECTION
The CS5378 digital filter can apply gain and offset
corrections to the measurement data. Also, an offset calibration algorithm can automatically calculate the offset correction value.
A gain correction value is written to the GAIN registers (0x21), while an offset correction value is
written to the OFFSET register (0x25). Gain and
offset corrections are enabled by the USEGR and
USEOR bits in the FILTCFG register (0x20).
When enabled, the offset calibration algorithm will
automatically calculate an offset correction value
and write it into the OFFSET register. Offset calibration is enabled by writing the EXP and ORCAL
bits in FILTCFG.
15.1 Gain Correction
Gain correction in the CS5378 normalizes sensor
gain in multi-sensor networks. It requires an externally calculated correction value to be written into
the GAIN register (0x21).
DS639F1
A gain correction value is 24-bit two’s complement
with unity gain defined as full scale, 0x7FFFFF.
Gain correction always scales to a fractional value,
and can never gain the digital filter data greater
than one.
Output Value = Data * (GAIN / 0x7FFFFF)
Unity Gain: GAIN = 0x7FFFFF
50% Gain: GAIN = 0x3FFFFF
Zero Gain: GAIN = 0x000000
Once the GAIN register is written, the USEGR bit
in the FILTCFG register enables gain correction.
15.2 Offset Correction
Offset correction in the CS5378 cancels the DC
bias of a measurement channel by subtracting the
value in the OFFSET register (0x25) from the digital filter output data word.
An offset correction value is 24-bit two’s complement with a maximum positive value of 0x7FFFFF,
56
CS5378
and a maximum negative value of 0x800000. If applying an offset correction causes the final result to
exceed a 24-bit two’s complement maximum, the
output data will saturate to that maximum value.
Output Data = Input Data - Offset Correction
Max Positive Output Value = 0x7FFFFF
Max Negative Output Value = 0x800000
Once the OFFSET register is written, the USEOR
bit in the FILTCFG register enables offset correction.
15.3 Offset Calibration
An offset calibration algorithm in the CS5378 can
automatically calculate an offset correction value.
When using the offset calibration algorithm, background noise data should be used as the input signal
for calculating the offset of the measurement channel.
The offset calibration algorithm is an exponential
averaging function that places increased weight on
more recent digital filter data. The exponential
weighting factor is set by the EXP bits in the
DS639F1
FILTCFG register, with larger exponent values
producing a smoother averaging function that requires a longer settling time, and smaller values
producing a noisier averaging function that requires a shorter settling time. Typical exponential
values range from 0x05 to 0x0F, depending on the
available settling time.
The characteristic equations of the offset calibration algorithm include an input value, X, an output
value, Y, a summation value, YSUM, a sample index, n, and an exponential value, EXP.
Y(n) = X(n) - [YSUM(n-1) >> EXP]
YSUM(n) = Y(n) + YSUM(n-1)
Offset Correction = YSUM >> EXP
Once the EXP bits are written, the ORCAL bit in
the FILTCFG register is set to enable offset calibration. When enabled, an updated offset correction
value is automatically written to the OFFSET register. When the offset calibration algorithm is fully
settled, the ORCAL bit should be cleared to maintain the final value in the OFFSET register.
57
CS5378
System Telemetry
CS5378
DRDY
SCK
MISO
Data Ready
Clock Out
Data In
Figure 33. Serial Data Interface Block Diagram
16. SERIAL DATA INTERFACE
Once digital filtering is complete, each 24-bit output sample is combined with an 8-bit status byte.
These data words are written to an 8-deep FIFO
buffer and then transmitted to the communications
channel through a high speed serial data interface.
MISO - Pin 25
Serial data output.
16.2 Serial Data Format
Data ready output signal, active low. Open drain
output requiring an external pull-up resistor.
Serial data transactions transfer either 24-bit data
words or 32-bit status+data words, depending on
the STAT bit in the CONFIG register. When transmitting status information, each 8-bit status byte
has an MFLAG bit, a time break bit, and a FIFO
overflow bit encoded as shown in Figure 34.
SCK - Pin 24
MFLAG Bit - MFLAG
Serial clock input.
The MFLAG bit is set in the status byte when an
signal is received on the MFLAG pin. When re-
16.1 Pin Descriptions
DRDY - Pin 23
31
23
0
Status
MFLAG
31
-30
0 - Modulator Ok
1 - Modulator Error
-29
Data
-28
-27
TB
26
-25
0 - No Time Break
1 - Time Break
W
24
0 - FIFO Ok
1 - FIFO Overflow
Figure 34. 32-bit Serial Data Format
DS639F1
58
CS5378
ceived, the MFLAG bit is set in the next output
word. See “Modulator Interface” on page 36 for
more information about MFLAG.
Time Break Bit - TB
The time break bit marks a timing reference based
on a rising edge into the TIMEB pin. After a programmed delay, the TB bit in the status byte is set
for one output sample. The TIMEBRK digital filter register (0x29) programs the sample delay for
the TB bit output. See “Time Break Controller” on
page 63 for more information about time break.
FIFO Overflow Bit - W
The FIFO overflow bit indicates an error condition
in the serial data FIFO, and is set if new digital filter data overwrites a FIFO location containing data
which has not yet been sent.
The W bit is sticky, meaning it persists indefinitely
once set. Clearing the W bit requires sending the
‘Filter Stop’ and ‘Filter Start’ configuration commands to reinitialize the data FIFO.
Conversion Data Word
The lower 24-bits of the serial data word is the conversion sample for the specified channel. Conversion data is 24-bit two’s complement format.
16.3 Serial Data Transactions
The CS5378 automatically initiates serial data
transactions whenever data becomes available in
the output FIFO by driving the DRDY pin low.
Once a serial data transaction is initiated, serial
clocks received into SCK cause data to be output to
MISO, as shown in Figure 35. When all available
data is read from the serial data FIFO, DRDY is released.
DRDY
SCK
MISO
MSB
LSB
Figure 35. SD Port Transaction
DS639F1
59
CS5378
Digital Filter
Data Bus
24-bit
TBSGAIN Register
24-bit
Digital ∆Σ Modulator
1-bit
TBSDATA
Figure 36. Test Bit Stream Generator Block Diagram
17. TEST BIT STREAM GENERATOR
The CS5378 test bit stream (TBS) generator creates
sine wave or impulse ∆Σ bit stream data to drive an
external test DAC. The TBS digital output can also
be internally connected to the MDATA inputs for
loopback testing of the digital filter.
17.3 TBS Configuration
17.1 Pin Descriptions
Interpolation Factor - INTP[7:0]
TBSDATA - Pin 8
MCLK - Pin 11
Selects how many times the interpolator uses a data
point when generating the output bit stream. Interpolation is zero based and represents one greater
than the programmed register value.
Test bit stream clock output.
Operational Mode - TMODE
Test bit stream 1-bit ∆Σ data output.
17.2 TBS Architecture
The test bit stream generator consists of a data interpolator and a digital ∆Σ modulator. It receives
periodic 24-bit data from the digital filter to create
a 1-bit ∆Σ data output on the TBSDATA pin.
The TBS input data from the digital filter is scaled
by the TBSGAIN register (0x2B). Maximum stable amplitude is 0x04FFFF, with 0x04B000 approximately full scale for the CS4373 test DAC.
The full scale 1-bit ∆Σ output from the TBS generator is defined as 25% minimum and 75% maximum one’s density.
DS639F1
Configuration options for the TBS generator are set
through the TBSCFG register (0x2A). Gain scaling of the TBS generator output is set by the TBSGAIN register (0x2B).
Selects between sine wave or impulse output mode.
Output Rate - RATE[2:0]
Selects the TBSDATA output rate.
Synchronization - TSYNC
Enables synchronization of the TBS output phase
to the MSYNC signal.
Loopback - LOOP
Enables digital loopback from the TBS output to
the MDATA inputs.
60
CS5378
Test Bit Stream Characteristic Equation:
(Signal Freq) * (# TBS Data) * (Interpolation + 1) = Output Rate
Example: (31.25 Hz) * (1024) * (0x07 + 1) = 256 kHz
Signal
Frequency
(TBSDATA)
Output
Rate
(TBSCLK)
Output Rate
Selection
(RATE)
Interpolation
Selection
(INTP)
10.00 Hz
256 kHz
0x4
0x18
10.00 Hz
512 kHz
0x5
0x31
25.00 Hz
256 kHz
0x4
0x09
25.00 Hz
512 kHz
0x5
0x13
31.25 Hz
256 kHz
0x4
0x07
31.25 Hz
512 kHz
0x5
0x0F
50.00 Hz
256 kHz
0x4
0x04
50.00 Hz
512 kHz
0x5
0x09
125.00 Hz
256 kHz
0x4
0x01
125.00 Hz
512 kHz
0x5
0x03
Table 18. TBS Configurations Using On-chip Data
Run - RUN
17.5 TBS Sine Wave Output
Enables the test bit stream generator.
When the TMODE bit in the TBSCFG register is
low, the TBS generator operates in sine wave
mode. In this mode, sine wave data from digital filter memory is used to create a sine wave test signal
that can drive a test DAC. Sine wave frequency
and output data rate are calculated as shown by the
characteristic equation of Table 18.
Data Delay - DDLY[5:0]
Programs full period delays for TBSDATA, up to a
maximum of 63 bits.
Gain - TBSGAIN[23:0]
Scales the amplitude of the sine wave output and
generated impulse. Maximum 0x04FFFF, nominal
0x04B000.
17.4 TBS Data Source
An on-chip 24-bit 1024 point digital sine wave is
stored on the CS5378 which will produce the test
signal frequencies listed in Table 18. Additional
discrete test frequencies and output rates can be
programmed by varying the interpolation factor
and output rate.
DS639F1
The sine wave maximum ∆Σ one’s density output
from the TBS generator is set by the TBSGAIN
register. TBSGAIN can be programmed up to a
maximum of 0x04FFFF, with the TBS generator
unstable for higher amplitudes. For the CS4373
test DAC, a gain value of 0x04B000 produces an
approximately full scale sine wave output (5 Vpp
differential).
61
CS5378
Test Bit Stream Impulse Characteristics:
Interpolation
Selection
(INTP)
Output Rate
Selection
(RATE)
Pulse Width
from CS4373
Gain Scale
Factor
(TBSGAIN)
Pulse Height
from CS4373
0xFF
0x5
500 µs
0x04B000
~ 860 mV
0xFF
0x4
1 ms
0x04B000
~ 820 mV
0xFF
0x3
2 ms
0x04B000
~ 820 mV
0x7F
0x5
250 µs
0x04B000
~ 820 mV
0x7F
0x4
500 µs
0x04B000
~ 820 mV
0x7F
0x3
1 ms
0x04B000
~ 820 mV
Table 19. TBS Impulse Characteristics
17.6 TBS Impulse Output
If the TMODE bit in TBSCFG is set high, the TBS
generator operates in impulse mode. In this mode,
the value in TBSGAIN sets the amplitude of the
generated impulse. Impulse amplitude and period
are shown in Table 19.
To create a maximum impulse from the TBS generator, the TBSGAIN register should be set to
0x04FFFF, and the INTP bits in TBSCFG should
also be set to 0xFF. The RATE bits should always
be set to produce data at the correct rate for the intended test DAC.
A rising edge on the TIMEB pin triggers the impulse output. When impulse mode is enabled but
no TIMEB input is received, the TBS generator
uses a negated TBSGAIN register as a repetitive input value. When a rising edge is recognized on the
TIMEB pin, a single positive TBSGAIN value is
written to the TBS generator to create the impulse.
17.7 TBS Loopback Testing
Included as part of the CS5378 test bit stream generator is a feedback path to the digital filter MDATA input. This loopback mode provides a fully
digital signal path to test the TBS generator, digital
DS639F1
filter, and data collection interface. Digital loopback testing expects 512 kHz ∆Σ data into the
MDATA input.
A mismatch of the TBS generator full scale output
and the MDATA full scale input results in an amplitude mismatch when testing in loopback mode.
The TBS generator outputs a 75% maximum one’s
density, while the MDATA inputs expect an 86%
maximum one’s density from a ∆Σ modulator, resulting in a measured full scale error of approximately -3.6 dB.
17.8 TBS Synchronization
When the TSYNC bit is set in the TBSCFG register, the MSYNC signal resets the sine wave data
pointer and phase aligns the TBS signal output.
Once the digital filter is settled, all CS5378 devices
receiving the SYNC signal will have identical TBS
signal phase. See “Synchronization” on page 24
for more information about the SYNC and
MSYNC signals.
If TSYNC is clear, MSYNC has no effect on the
TBS data pointer and no change in the TBS output
phase will occur during synchronization.
62
CS5378
TIMEBRK
Delay Counter
TIMEB
TB Flag
in Serial Data
Status Byte
Figure 37. Time Break Block Diagram
18. TIME BREAK CONTROLLER
A time break signal is used to mark timing events
that occur during measurement. An external signal
sets a flag in the status byte of an output sample to
mark when the external event occurred.
A rising edge input to the TIMEB pin causes the
TB timing reference flag to be set in the serial data
status byte. When set, the TB flag appears for only
one output sample in the status byte. The TB flag
output can be delayed by programming a sample
delay value into the TIMEBRK digital filter register.
18.1 Pin Description
TIMEB - Pin 20
Time break input pin, rising edge triggered.
18.2 Time Break Operation
An externally generated timing reference signal applied to the TIMEB pin initiates an internal sample
counter. After a number of output samples have
passed, programmed in the TIMEBRK digital filter
register (0x29), the TB flag is set in the status byte
of the serial data output word. The TB flag is automatically cleared for subsequent data words, and
appears for only one output sample.
DS639F1
18.3 Time Break Delay
The TIMEBRK register (0x29) sets a sample delay
between a received rising edge on the TIMEB pin
and writing the TB flag into the serial data status
byte.
The programmable sample counter can compensate
for group delay through the digital filters. When the
proper group delay value is programmed into the
TIMEBRK register, the TB flag will be set in the
status byte of the measurement sample taken when
the timing reference signal was received.
18.3.1 Step Input and Group Delay
A simple method to empirically measure the step
response and group delay of a CS5378 measurement channel is to use the time break signal as both
a timing reference input and an analog step input.
When a rising edge is received on the TIMEB pin
with no delay programmed into the TIMEBRK register, the TB flag is set in the next serial data status
byte. The same rising edge can act as a step input
to the analog channel, propagating through the digital filter to appear as a rising edge in the measurement data. By comparing the timing of the TB
status flag output and the rising edge in the measurement data, the measurement channel group delay can be determined.
63
CS5378
GP_PULL
Pull Up
Logic
R
GPIO
GP_DATA
GP_DIR
Figure 38. GPIO Block Diagram
19. GENERAL PURPOSE I/O
The General Purpose I/O (GPIO) block provides 8
general purpose pins to interface with external
hardware.
GP_PULL bits enable/disable the internal pull-up
resistor, and GP_DATA bits set the output data value. After reset, GPIO pins default as inputs with
pull-up resistors enabled.
19.1 Pin Descriptions
GPIO[3:0] - Pins 4 - 1
19.4 GPIO Input Mode
Standard GPIO pins also used to select the PLL
mode after reset. Internal pull-ups default high,
10 kΩ external pull-downs required to set low.
When reading a value from the GP_DATA bits, the
returned data reports the current state of the pins. If
a pin is externally driven high it reads a logical 1, if
externally driven low it reads a logical 0. When a
GPIO pin is used as an input, the pull-up resistor
should be disabled to save power if it isn’t required.
GPIO7:BOOT - Pin 28
19.5 GPIO Output Mode
Standard GPIO pin also used to select boot mode
after reset. Internal pull-up defaults high, 10 kΩ external pull-down required to set low.
When a GPIO pin is programmed as an output with
a data value of 0, the pin is driven low and the internal pull-up resistor is automatically disabled.
When programmed as an output with a data value
of 1, the pin is driven high and the pull-up resistor
is inconsequential.
Standard GPIO pins.
GPIO[6:4]:PLL[2:0] - Pins 7 - 5
19.2 GPIO Architecture
Each GPIO pin can be configured as input or output, high or low, with a weak (~100 kΩ) internal
pull-up resistor enabled or disabled. Figure 38
shows the structure of a bi-directional GPIO pin.
19.3 GPIO Registers
GPIO pin settings are programmed in the GPCFG
register. GP_DIR bits set the input/output mode,
DS639F1
Any GPIO pin can be used as an open-drain output
by setting the data value to 0, enabling the pull-up,
and using the GP_DIR direction bits to control the
pin value. This open-drain output configuration
uses the internal pull-up resistor to hold the pin
high when GP_DIR is set as an input, and drives the
pin low when GP_DIR is set as an output.
64
CS5378
19.5.1 GPIO Reads in Output Mode
When reading GPIO pins the GP_DATA register
value always reports the current state of the pins, so
a value written in output mode does not necessarily
read back the same value. If a pin in output mode is
written as a logical 1, the CS5378 attempts to drive
the pin high. If an external device forces the pin
DS639F1
low, the read value reflects the pin state and returns
a logical 0. Similarly, if an output pin is written as
a logical 0 but forced high externally, the read value reflects the pin state and returns a logical 1. In
both cases the CS5378 is in contention with the external device resulting in increased power consumption.
65
CS5378
20. REGISTER SUMMARY
20.1 SPI Registers
The CS5378 SPI registers interface the serial port to the digital filter.
Name
Addr.
Type
# Bits
SPICTRLH
00
R/W
8
SPI Control Register, High Byte
SPICTRLM
01
R/W
8
SPI Control Register, Middle Byte
SPICTRLL
02
R/W
8
SPI Control Register, Low Byte
SPICMDH
03
R/W
8
SPI Command, High Byte
SPICMDM
04
R/W
8
SPI Command, Middle Byte
SPICMDL
05
R/W
8
SPI Command, Low Byte
SPIDAT1H
06
R/W
8
SPI Data 1, High Byte
SPIDAT1M
07
R/W
8
SPI Data 1, Middle Byte
SPIDAT1L
08
R/W
8
SPI Data 1, Low Byte
SPIDAT2H
09
R/W
8
SPI Data 2, High Byte
SPIDAT2M
0A
R/W
8
SPI Data 2, Middle Byte
SPIDAT2L
0B
R/W
8
SPI Data 2, Low Byte
DS639F1
Description
66
CS5378
20.1.1
SPICTRL : 0x00, 0x01, 0x02
Figure 39. SPI Control Register SPICTRL
(MSB) 23
22
21
20
19
18
17
16
--
--
--
--
--
--
--
--
R/W
R/W1
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
1
0
1
1
15
14
13
12
11
10
9
8
SMODF
--
--
EMOP
SWEF
--
--
E2DREQ
R
R/W
R
R
R
R/W
R/W
R/W
0
0
0
0
0
0
1
0
7
6
5
4
3
2
1
(LSB) 0
--
--
--
--
--
--
--
--
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
1
0
0
0
0
0
15
SMODF
SPI Address: 0x00
0x01
0x02
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 --
DS639F1
reserved
SPI mode fault flag
14:13 --
reserved
12
EMOP
External master to SPI
operation in progress
flag
11
SWEF
SPI write collision error
flag
10:9
--
reserved
8
E2DREQ External master to digital
filter request flag
7:0
--
reserved
67
CS5378
20.1.2
SPICMD : 0x03, 0x04, 0x05
Figure 40. SPI Command Register SPICMD
(MSB) 23
22
21
20
19
18
17
16
SCMD23
SCMD22
SCMD21
SCMD20
SCMD19
SCMD18
SCMD17
SCMD16
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
SCMD15
SCMD14
SCMD13
SCMD12
SCMD11
SCMD10
SCMD9
SCMD8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
SPI Address: 0x03
0x04
0x05
--
7
6
5
4
3
2
1
(LSB) 0
SCMD7
SCMD6
SCMD5
SCMD4
SCMD3
SCMD2
SCMD1
SCMD0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 SCMD[23:16]
DS639F1
SPI Command High 15:8
Byte
SCMD[15:8]
SPI Command Mid- 15:8
dle Byte
SCMD[7:0]
SPI Command
Low Byte
68
CS5378
20.1.3
SPIDAT1 : 0x06, 0x07, 0x08
Figure 41. SPI Data Register SPIDAT1
(MSB) 23
22
21
20
19
18
17
16
SDAT23
SDAT22
SDAT21
SDAT20
SDAT19
SDAT18
SDAT17
SDAT16
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
SDAT15
SDAT14
SDAT13
SDAT12
SDAT11
SDAT10
SDAT9
SDAT8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
SPI Address: 0x06
0x07
0x08
--
7
6
5
4
3
2
1
(LSB) 0
SDAT7
SDAT6
SDAT5
SDAT4
SDAT3
SDAT2
SDAT1
SDAT0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 SDAT[23:16] SPI Data
High Byte
DS639F1
15:8
SDAT[15:8]
SPI Data
Middle Byte
15:8
SDAT[7:0]
SPI Data
Low Byte
69
CS5378
20.1.4
SPIDAT2 : 0x09, 0x0A, 0x0B
Figure 42. SPI Data Register SPIDAT2
(MSB) 23
22
21
20
19
18
17
16
SDAT23
SDAT22
SDAT21
SDAT20
SDAT19
SDAT18
SDAT17
SDAT16
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
SDAT15
SDAT14
SDAT13
SDAT12
SDAT11
SDAT10
SDAT9
SDAT8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
SPI Address: 0x09
0x0A
0x0B
--
7
6
5
4
3
2
1
(LSB) 0
SDAT7
SDAT6
SDAT5
SDAT4
SDAT3
SDAT2
SDAT1
SDAT0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 SDAT[23:16] SPI Data
High Byte
DS639F1
15:8
SDAT[15:8]
SPI Data
Middle Byte
15:8
SDAT[7:0]
SPI Data
Low Byte
70
CS5378
20.2
Digital Filter Registers
The CS5378 digital filter registers control hardware peripherals and filtering functions.
Name
Addr.
Type
# Bits
00
R/W
24
Hardware Configuration
01-0D
R/W
24
Reserved
0E
R/W
24
GPIO[7:0] Direction, Pull-Up Enable, and Data
0F-1F
R/W
24
Reserved
FILTCFG
20
R/W
24
Digital Filter Configuration
GAIN
21
R/W
24
Gain Correction
22-24
R/W
24
Reserved
25
R/W
24
Offset Correction
RESERVED
26-28
R/W
24
Reserved
TIMEBRK
29
R/W
24
Time Break Delay
TBSCFG
2A
R/W
24
Test Bit Stream Configuration
TBSGAIN
2B
R/W
24
Test Bit Stream Gain
SYSTEM1
2C
R/W
24
User Defined System Register 1
SYSTEM2
2D
R/W
24
User Defined System Register 2
VERSION
2E
R/W
24
Hardware Version ID
SELFTEST
2F
R/W
24
Self-Test Result Code
CONFIG
RESERVED
GPCFG
RESERVED
RESERVED
OFFSET
DS639F1
Description
71
CS5378
20.2.1
CONFIG : 0x00
Figure 43. Hardware Configuration Register CONFIG
(MSB)23
22
21
20
19
18
17
16
--
--
--
--
--
DFS2
DFS1
DFS0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
1
0
1
15
14
13
12
11
10
9
8
--
--
--
--
--
MCKFS2
MCKFS1
MCKFS0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
1
0
0
7
6
5
4
3
2
1
(LSB)0
STAT
--
MCKEN2
MCKEN
MDIFS
--
BOOT
MSEN
R/W
R/W
R/W
R/W
R/W
R/W
R
R/W
0
0
0
0
0
0
0
1
DF Address: 0x00
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:19 --
reserved
15:11 --
reserved
18:16 DFS
[2:0]
Digital filter
frequency select
111: Reserved
110: 8.192 MHz
101: 4.096 MHz
100: 2.048 MHz
011: 1.024 MHz
010: 512 kHz
001: 256 kHz
000: 32 kHz
10:8
MCLK frequency select 5
111: reserved
110: reserved
101: 4.096 MHz
100: 2.048 MHz
4
011: 1.024 MHz
010: 512 kHz
001: reserved
000: reserved
3
DS639F1
MCKFS
[2:0]
7:6
STAT
Serial Data Status Byte
1: Disabled (24-bit output)
0: Enabled (32-bit output)
MCKEN2
MCLK/2 output enable
1: Enabled
0: Disabled
MCKEN
MCLK output enable
1: Enabled
0: Disabled
MDIFS
MDATA input frequency
select
1: 256 kHz
0: 512 kHz
2
--
reserved
1
BOOT
Boot source indicator
1: Booted from EEPROM
0: Booted from Micro
0
MSEN
MSYNC enable
1: MSYNC generated
0: MSYNC remains low
72
CS5378
20.2.2
GPCFG : 0x0E
Figure 44. GPIO Configuration Register GPCFG
(MSB) 23
22
21
20
19
18
17
16
GP_DIR7
GP_DIR6
GP_DIR5
GP_DIR4
GP_DIR3
GP_DIR2
GP_DIR1
GP_DIR0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
GP_PULL7
GP_PULL6
GP_PULL5
GP_PULL4
GP_PULL3
GP_PULL2
GP_PULL1
GP_PULL0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
1
1
1
1
1
1
1
7
6
5
4
3
2
1
(LSB) 0
GP_DATA7
GP_DATA6
GP_DATA5
GP_DATA4
GP_DATA3
GP_DATA2
GP_DATA1
GP_DATA0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
1
1
1
1
1
1
1
DF Address: 0x0E
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 GP_DIR
[7:0]
GPIO pin direction
1: Output
0: Input
15:8
GP_PULL GPIO pullup resistor
[7:0]
1: Enabled
0: Disabled
7:0
GP_DATA GPIO data value
[7:0]
1: VDD
0: GND
Notes:
GPIO[7] also used as BOOT mode select after reset
GPIO[6:4] also used as PLL mode select after reset.
DS639F1
73
CS5378
20.2.3
FILTCFG : 0x20
Figure 45. Filter Configuration Register FILTCFG
(MSB) 23
22
21
20
19
18
17
16
--
--
--
EXP4
EXP3
EXP2
EXP1
EXP0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
--
ORCAL
USEOR
USEGR
--
FSEL2
FSEL1
FSEL0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
DEC3
DEC2
DEC1
DEC0
--
--
--
(LSB) 0
--
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
DF Address: 0x20
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:21 --
reserved
20:16 EXP[4:0] OFFSET calibration
exponent
DS639F1
15
--
reserved
7:4
14
ORCAL
Run OFFSET calibration
1: Enable
0: Disable
0111:
0110:
0101:
0100:
0011:
4000 SPS
2000 SPS
1000 SPS
500 SPS
333 SPS
13
USEOR
Use OFFSET correction
1: Enable
0: Disable
0010:
0001:
0000:
1111:
1110:
250 SPS
200 SPS
125 SPS
100 SPS
50 SPS
12
USEGR
Use GAIN correction
1: Enable
0: Disable
1101:
1100:
1011:
1010:
1001:
1000:
40 SPS
25 SPS
20 SPS
10 SPS
5 SPS
1 SPS
11
--
reserved
10:8
FSEL[2:0] Output filter stage select
111: reserved
110: reserved
101: IIR 3rd Order
100: IIR 2nd Order
011: IIR 1st Order
010: FIR2 Output
001: FIR1 Output
000: SINC Output
3:0
DEC[3:0]
--
Decimation selection
(Output word rate)
reserved
74
CS5378
20.2.4
GAIN : 0x21
Figure 46. Gain Correction Register GAIN
(MSB) 23
22
21
20
19
18
17
16
GAIN23
GAIN22
GAIN21
GAIN20
GAIN19
GAIN18
GAIN17
GAIN16
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
GAIN15
GAIN14
GAIN13
GAIN12
GAIN11
GAIN10
GAIN9
GAIN8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
(LSB) 0
GAIN7
GAIN6
GAIN5
GAIN4
GAIN3
GAIN2
GAIN1
GAIN0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
DF Address: 0x21
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 GAIN[23:16] Gain Correction
Upper Byte
DS639F1
15:8
GAIN[15:8]
Gain Correction
Middle Byte
15:8
GAIN[7:0]
Gain Correction
Lower Byte
75
CS5378
20.2.5
OFFSET : 0x25
Figure 47. Offset Correction Register OFFSET
(MSB) 23
22
21
20
19
18
17
16
OFST23
OFST22
OFST21
OFST20
OFST19
OFST18
OFST17
OFST16
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
OFST15
OFST14
OFST13
OFST12
OFST11
OFST10
OFST9
OFST8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
(LSB) 0
OFST7
OFST6
OFST5
OFST4
OFST3
OFST2
OFST1
OFST0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
DF Address: 0x25
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 OFST[23:16]
DS639F1
Offset Correction
Upper Byte
15:8
OFST[15:8]
Offset Correction
Middle Byte
15:8
OFST[7:0]
Offset Correction
Lower Byte
76
CS5378
20.2.6
TIMEBRK : 0x29
Figure 48. Time Break Counter Register TIMEBRK
(MSB) 23
22
21
20
19
18
17
16
TBRK23
TBRK22
TBRK21
TBRK20
TBRK19
TBRK18
TBRK17
TBRK16
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
TBRK15
TBRK14
TBRK13
TBRK12
TBRK11
TBRK10
TBRK9
TBRK8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
(LSB) 0
TBRK7
TBRK6
TBRK5
TBRK4
TBRK3
TBRK2
TBRK1
TBRK0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
DF Address: 0x29
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 TBRK[23:16] Time Break Counter 15:8
Upper Byte
DS639F1
TBRK[15:8] Time Break Counter 15:8
Middle Byte
TBRK[7:0]
Time Break Counter
Lower Byte
77
CS5378
20.2.7
TBSCFG : 0x2A
Figure 49. Test Bit Stream Configuration Register TBSCFG
(MSB) 23
22
21
20
19
18
17
16
INTP7
INTP6
INTP5
INTP4
INTP3
INTP2
INTP1
INTP0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
TMODE
RATE2
RATE1
RATE0
TSYNC
--
--
--
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
(LSB) 0
LOOP
RUN
DDLY5
DDLY4
DDLY3
DDLY2
DDLY1
DDLY0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Interpolation factor
0xFF: 256
0xFE: 255
...
0x01: 2
0x00: 1 (use once)
15
DF Address: 0x2A
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 INTP[7:0]
DS639F1
Operational mode
1: Impulse mode
0: Sine Mode
7
LOOP
Loopback
TBSDATA output
to MDATA inputs
1: Enabled
0: Disabled
14:12 RATE[2:0]
TBSDATA and
TBSCLK output
rate.
111: 2.048 MHz
110: 1.024 MHz
101: 512 kHz
100: 256 kHz
011: 128 kHz
010: 64 kHz
001: 32 kHz
000: 4 kHz
6
RUN
Run Test Bit Stream
1: Enabled
0: Disabled
11
TSYNC
Synchronization
1: Sync enabled
0: No sync
5:0
DDLY[5:0]
TBSDATA output
delay
0x3F: 63 bits
0x3E: 62 bits
...
0x01: 1 bit
0x00: 0 bits ( no
delay)
10:8
--
reserved
TMODE
78
CS5378
20.2.8
TBSGAIN : 0x2B
Figure 50. Test Bit Stream Gain Register TBSGAIN
(MSB) 23
22
21
20
19
18
17
16
TGAIN23
TGAIN22
TGAIN21
TGAIN20
TGAIN19
TGAIN18
TGAIN17
TGAIN16
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
TGAIN15
TGAIN14
TGAIN13
TGAIN12
TGAIN11
TGAIN10
TGAIN9
TGAIN8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
(LSB) 0
TGAIN7
TGAIN6
TGAIN5
TGAIN4
TGAIN3
TGAIN2
TGAIN1
TGAIN0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
DF Address: 0x2B
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 TGAIN[23:16] Test Bit Stream Gain 15:8
Upper Byte
DS639F1
TGAIN[15:8] Test Bit Stream
Gain Middle Byte
15:8
TGAIN[7:0] Test Bit Stream
Gain Lower Byte
79
CS5378
20.2.9
SYSTEM1, SYSTEM2 : 0x2C, 0x2D
Figure 51. User Defined System Register SYSTEM1
(MSB) 23
22
21
20
19
18
17
16
SYS23
SYS22
SYS21
SYS20
SYS19
SYS18
SYS17
SYS16
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
SYS15
SYS14
SYS13
SYS12
SYS11
SYS10
SYS9
SYS8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
(LSB) 0
SYS7
SYS6
SYS5
SYS4
SYS3
SYS2
SYS1
SYS0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
DF Address: 0x2C
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 SYS[23:16]
DS639F1
System Register
Upper Byte
15:8
SYS[15:8]
System Register
Middle Byte
15:8
SYS[7:0]
System Register
Lower Byte
80
CS5378
20.2.10
VERSION : 0x2E
Figure 52. Hardware Version ID Register VERSION
(MSB) 23
22
21
20
19
18
17
16
TYPE7
TYPE6
TYPE5
TYPE4
TYPE3
TYPE2
TYPE1
TYPE0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
1
1
1
1
0
0
0
15
14
13
12
11
10
9
8
HW7
HW6
HW5
HW4
HW3
HW2
HW1
HW0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
1
7
6
5
4
3
2
1
(LSB) 0
ROM7
ROM6
ROM5
ROM4
ROM3
ROM2
ROM1
ROM0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
1
DF Address: 0x2E
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:16 TYPE
[7:0]
DS639F1
Chip Type
78 - CS5378
15:8
HW
[7:0]
Hardware Revision
01 - CS5378 Rev A
7:4
ROM
[7:0]
ROM Version
01 - Ver 1.0
81
CS5378
20.2.11
SELFTEST : 0x2F
Figure 53. Self Test Result Register SELFTEST
(MSB) 23
22
21
20
19
18
17
16
--
--
--
--
EU3
EU2
EU1
EU0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
1
0
1
0
15
14
13
12
11
10
9
8
DRAM3
DRAM2
DRAM1
DRAM0
PRAM3
PRAM2
PRAM1
PRAM0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
0
1
0
1
0
1
0
7
6
5
4
3
2
1
(LSB) 0
DROM3
DROM2
DROM1
DROM0
PROM3
PROM2
PROM1
PROM0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
0
1
0
1
0
1
0
DF Address: 0x2F
-R
W
R/W
Not defined;
read as 0
Readable
Writable
Readable and
Writable
Bits in bottom rows
are reset condition
Bit definitions:
23:20 --
reserved
15:12 DRAM
[3:0]
Data RAM Test
‘A’: Pass
‘F’: Fail
7:4
DROM
[3:0]
Data ROM Test
‘A’: Pass
‘F’: Fail
19:16 EU
[3:0]
Execution Unit Test
‘A’: Pass
‘F’: Fail
11:8
Program RAM Test
‘A’: Pass
‘F’: Fail
3:0
PROM
[3:0]
Program ROM Test
‘A’: Pass
‘F’: Fail
DS639F1
PRAM
[3:0]
82
CS5378
21. PIN DESCRIPTION
GPIO0
1
28
GPIO7:BOOT
GPIO1
2
27
SS:EECS
GPIO2
3
26
MOSI
GPIO3
4
25
MISO
GPIO4:PLL0
5
24
SCK
GPIO5:PLL1
6
23
DRDY
GPIO6:PLL2
7
22
GNDCORE
TBSDATA
8
21
VDDCORE
VDDPAD
9
20
TIMEB
GNDPAD
10
19
SYNC
MCLK
11
18
RESET
MSYNC
12
17
CLK
MDATA
13
16
GNDPLL
MFLAG
14
15
VDDPLL
Figure 54. CS5378 Pin Assignments
Pin
Name
Pin
Number
Pin
Type
Pin
Description
GPIO[0:3]
1, 2, 3, 4
Input / Output
General Purpose I/O.
GPIO[4:6]:PLL[0:2]
5, 6, 7
Input / Output
General Purpose I/O with PLL mode select.
GPIO pins have weak (~100 kΩ) internal pullups.
PLL mode selection latched immediately after reset.
General Purpose Input / Output
PLL[2:0]
GPIO7:BOOT
28
Input / Output
32.768 MHz clock input (PLL bypass).
110
1.024 MHz clock input.
101
2.048 MHz clock input.
100
4.096 MHz clock input.
011
32.768 MHz clock input (PLL bypass).
010
1.024 MHz manchester input.
001
2.048 MHz manchester input.
000
4.096 MHz manchester input.
General Purpose I/O with boot mode select.
GPIO pins have weak (~100 kΩ) internal pullups.
Boot mode selection latched immediately after reset.
BOOT
DS639F1
Reset Mode
111
Reset Mode
1
EEPROM boot
0
Microcontroller boot
83
CS5378
Pin
Name
Pin
Number
Pin
Type
Pin
Description
TBSDATA
8
Output
MCLK
11
Output
Modulator clock output.
MSYNC
12
Output
Modulator sync output.
MDATA
13
Input
Modulator data input.
MFLAG
14
Input
Modulator flag input.
CLK
17
Input
Clock input.
Test Bit Stream
Test bit stream data output.
Modulator Interface
Telemetry Interface
RESET
18
Input
Reset, active low.
SYNC
19
Input
Sync input.
TIMEB
20
Input
Time break input.
Serial Interface
DRDY
23
Output
Data ready, active low.
SCK
24
Input / Output
Serial clock.
MISO
25
Input / Output
Serial data, master in / slave out.
MOSI
26
Input / Output
Serial data, master out / slave in.
SS:EECS
27
Input
Slave select with EEPROM chip select, active low.
VDDPAD,
GNDPAD
9, 10
Supply
Pin power supply.
VDDPLL,
GNDPLL
15, 16
Supply
PLL power supply.
VDDCORE,
GNDCORE
21, 22
Supply
Logic core power supply.
Power Supplies
DS639F1
84
CS5378
22.PACKAGE DIMENSIONS
28L SSOP PACKAGE DRAWING
N
D
E11
A2
E
e
b2
SIDE VIEW
A
∝
A1
L
END VIEW
SEATING
PLANE
1 2 3
TOP VIEW
DIM
A
A1
A2
b
D
E
E1
e
L
∝
MIN
-0.002
0.064
0.009
0.390
0.291
0.197
0.022
0.025
0°
INCHES
NOM
-0.006
0.069
-0.4015
0.307
0.209
0.026
0.0354
4°
MAX
0.084
0.010
0.074
0.015
0.413
0.323
0.220
0.030
0.041
8°
MIN
-0.05
1.62
0.22
9.90
7.40
5.00
0.55
0.63
0°
MILLIMETERS
NOM
-0.15
1.75
-10.20
7.80
5.30
0.65
0.90
4°
NOTE
MAX
2.13
0.25
1.88
0.38
10.50
8.20
5.60
0.75
1.03
8°
2,3
1
1
JEDEC #: MO-150
Controlling Dimension is Millimeters
DS639F1
85
CS5378
23.ORDERING INFORMATION
Model
CS5378-IS
CS5378-ISZ Lead Free
Temperature
Package
-40 to +85 °C
28-pin SSOP
24.ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION
Model Number
Peak Reflow Temp
MSL Rating*
Max Floor Life
CS5378-IS
240 °C
2
365 Days
CS5378-ISZ Lead Free
260 °C
3
7 Days
* MSL (Moisture Sensitivity Level) as specified by IPC/JEDEC J-STD-020.
25.REVISION HISTORY
Revision
Date
Changes
PP1
FEB 2004
Initial “Preliminary Product” release.
F1
OCT 2005
Added lead-free device ordering information. Added MSL data.
Contacting Cirrus Logic Support
For all product questions and inquiries contact a Cirrus Logic Sales Representative.
To find the one nearest to you go to www.cirrus.com
IMPORTANT NOTICE
Cirrus Logic, Inc. and its subsidiaries ("Cirrus") believe that the information contained in this document is accurate and reliable. However, the information is subject
to change without notice and is provided "AS IS" without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant
information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale
supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus
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does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ("CRITICAL APPLICATIONS"). CIRRUS PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED FOR USE
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Cirrus Logic, Cirrus, and the Cirrus Logic logo designs are trademarks of Cirrus Logic, Inc. All other brand and product names in this document may be trademarks
or service marks of their respective owners.
SPI is a trademark of Motorola, Inc.
DS639F1
86