CS5321/22
24-bit, Variable-bandwidth A/D Converter Chipset
Features
Description
CMOS A/D Converter Chipset
Dynamic Range
The CS5321/CS5322 chipset functions as a unique
A/D converter intended for very high-resolution
measurement of signals below 1600 Hz. It is specifically designed for applications that require both a
high dynamic range and a low total harmonic distortion. The chipset performs sampling, A/D
conversion, and anti-alias filtering.
- 130 dB @ 25 Hz Bandwidth
- 121 dB @ 411 Hz Bandwidth
Delta-sigma Architecture
- Fourth-order Modulator
- Variable Oversampling: 64X to 4096X
- Internal Track-and-hold Amplifier
CS5321 Signal-to-distortion: 115 dB
Clock-jitter-tolerant Architecture
Input Voltage Range: +4.5 V
Flexible Filter Chip
- Hardware- or Software-selectable Options
- Seven Selectable Filter Corners (-3 dB)
Frequencies: 25, 51, 102, 205, 411, 824 and
1650 Hz
The CS5321 uses Delta-Sigma modulation to produce highly accurate conversions. The ∆Σ
modulator oversamples, virtually eliminating the
need for external analog anti-alias filters. The
CS5322 linear-phase FIR digital filter decimates the
output to any one of seven selectable update periods: 16, 8, 4, 2, 1, 0.5, and 0.25 milliseconds. Data
is output from the digital filter in a 24-bit serial
format.
ORDERING INFORMATION
Low Power Dissipation: <100 mW
See page 36.
CS5321
Vdd1 Vss1
Vdd2
CS5322
Vss2
VD+
LPWR
SYNC
CLKIN
CS R/W
RESET
RSEL
OFST
SCLK
SID
MSYNC
SOD
MFLG
AINR
AINVREF+
HBR
VREF-
http://www.cirrus.com
ERROR
DRDY
MDATA
MDATA
AGND
Digital
Filter
MCLK
Analog
Modulator
AIN+
DGND
ORCAL
DECA
VD+
DGND
CSEL
DECB
DECC
H/S
Copyright © Cirrus Logic, Inc. 2006
(All Rights Reserved)
TDATA
PWDN
USEOR
DGND
NOV ‘06
DS454F3
CS5321/22
TABLE OF CONTENTS
1. CHARACTERISTICS AND SPECIFICATIONS ............................................... 4
CS5321 ANALOG CHARACTERISTICS .................................................... 4
CS5321 SWITCHING CHARACTERISTICS .............................................. 6
CS5321 DIGITAL CHARACTERISTICS ..................................................... 7
CS5321 RECOMMENDED OPERATION CONDITIONS ........................... 7
CS5321 ABSOLUTE MAXIMUM RATINGS ............................................... 7
CS5322 FILTER CHARACTERISTICS ...................................................... 8
CS5322 POWER SUPPLY ....................................................................... 10
CS5322 SWITCHING CHARACTERISTICS ............................................ 10
CS5322 DIGITAL CHARACTERISTICS ................................................... 15
CS5322 RECOMMENDED OPERATION CONDITIONS ......................... 15
CS5322 ABSOLUTE MAXIMUM RATINGS ............................................. 15
2. GENERAL DESCRIPTION ............................................................................ 16
2.1. Analog Input ...................................................................................... 18
2.2. The OFST Pin.................................................................................... 18
2.3. Input Range and Overrange Conditions ............................................ 19
2.4. Voltage Reference ............................................................................. 20
2.5. Clock Source ..................................................................................... 20
2.6. Low Power Mode ............................................................................... 21
2.7. Digital Interface and Data Format...................................................... 21
2.8. Performance ...................................................................................... 22
2.9. Power Supply Considerations............................................................ 23
2.10. Power Supply Rejection Ratio ......................................................... 23
2.11. RESET Operation ............................................................................ 23
2.12. Power-down Operation .................................................................... 23
2.13. SYNC Operation .............................................................................. 24
2.14. Serial Read Operation ..................................................................... 24
2.15. Serial Write Operation ..................................................................... 24
2.16. Offset Calibration Operation ............................................................ 25
2.17. Status Bits ....................................................................................... 26
2.18. Board Layout Considerations .......................................................... 28
3. CS5321 PIN DESCRIPTIONS ....................................................................... 29
Power Supplies ......................................................................................... 29
Analog Inputs ............................................................................................ 29
Digital Inputs ............................................................................................. 30
Digital Outputs .......................................................................................... 30
4. CS5322 PIN DESCRIPTIONS ....................................................................... 31
Power Supplies ......................................................................................... 31
Digital Outputs .......................................................................................... 31
Digital Inputs ............................................................................................. 32
5. PARAMETER DEFINITIONS......................................................................... 34
6. PACKAGE DIMENSIONS.............................................................................. 35
7. ORDERING INFORMATION ......................................................................... 36
8. ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION ... 36
9. REVISION HISTORY .................................................................................... 36
2
DS454F3
CS5321/22
LIST OF FIGURES
Figure 1. Rise and Fall Times ..................................................................................... 6
Figure 2. CS5321 Interface Timing, HBR=1 ............................................................... 6
Figure 3. CS5322 Filter Response ............................................................................. 8
Figure 4. CS5322 Digital Filter Passband Ripple, f0 = 62.5 Hz .................................. 8
Figure 5. CS5322 Digital Filter Passband Ripple, f0 = 125 Hz ................................... 8
Figure 6. CS5322 Digital Filter Passband Ripple, f0 = 250 Hz ................................... 8
Figure 7. CS5322 Digital Filter Passband Ripple, f0 = 500 Hz ................................... 9
Figure 8. CS5322 Digital Filter Passband Ripple, f0 = 1000 Hz ................................. 9
Figure 9. CS5322 Digital Filter Passband Ripple, f0 = 2000 Hz ................................. 9
Figure 10. CS5322 Digital Filter Passband Ripple, f0 = 4000 Hz ............................... 9
Figure 11. CS5322 Impulse Response, f0 = 62.5 Hz .................................................. 9
Figure 12. CS5322 Impulse Response, f0 = 1000 Hz ................................................. 9
Figure 13. CS5322 Serial Port Timing ...................................................................... 11
Figure 14. TDATA Setup/Hold Timing ...................................................................... 12
Figure 15. DRDY Timing .......................................................................................... 13
Figure 16. RESET Timing ......................................................................................... 13
Figure 17. CS5321/CS5322 Interface Timing ........................................................... 14
Figure 18. CS5321 Block Diagram ........................................................................... 16
Figure 19. CS5322 Block Diagram ........................................................................... 17
Figure 20. System Connection Diagram ................................................................... 19
Figure 21. 4.5 Voltage Reference with two filter options .......................................... 20
Figure 22. 1024 Point FFT Plot with -20 dB Input,
100 Hz Input, ten averages 22
Figure 23. 1024 Point FFT Plot with Full Scale Input,
100 Hz Input, HBR = 1, ten averages ............................................. 22
Figure 24. 1024 Point FFT Plot with Full Scale Input,
100 Hz Input, HBR = 0, ten averages ............................................. 22
LIST OF TABLES
Table 1.
Table 2.
Table 3.
Table 4.
DS454F3
Output Coding for the CS5321 and CS5322 Combination ....................... 21
Configuration Data Bits ............................................................................ 25
Status Data (from the SOD Pin) ............................................................... 26
Bandwidth Selection: Truth Table ............................................................ 27
3
CS5321/22
1. CHARACTERISTICS AND SPECIFICATIONS
CS5321 ANALOG CHARACTERISTICS (TA = (See Note 1); Vss1, Vss2 = -5 V; Vdd1, Vdd2 = +5 V;
VD+ = 5 V; AGND = DGND = 0 V; HBR = Vdd LPWR = 0, MCLK = 1.024 MHz; Device connected as shown in Figure 20,
CS5322 used for filtering; Logic 1 = VD+, Logic 0 = 0V; unless otherwise specified.)
CS5321
Parameter*
Symbol
Min
Typ
Max
Unit
fO = 4000 Hz
fO = 2000 Hz
fO = 1000 Hz
fO = 500 Hz
fO = 250 Hz
fO = 125 Hz
fO = 62.5 Hz
116
-
103
118
121
124
127
129
130
-
dB
dB
dB
dB
dB
dB
dB
fO = 4000 Hz
fO = 2000 Hz
fO = 1000 Hz
fO = 500 Hz
fO = 250 Hz
fO = 125 Hz
fO = 62.5 Hz
-
99
115
118
121
124
126
127
-
dB
dB
dB
dB
dB
dB
dB
108
110
115
120
-
dB
dB
Dynamic Performance
Dynamic Range
HBR = 1
OFST = 1
HBR = 0
OFST = 1
Signal-to-Distortion
Intermodulation Distortion
(Note 2)
DR
(Note 3)
HBR = 1
HBR = 0
SDR
(Note 4)
IMD
-
110
-
dB
(Note 5)
FSE
-
1
-
%
(Note 5,6)
TCFS
-
5
-
ppm/°C
VZSE
DC Accuracy
Full Scale Error
Full Scale Drift
Offset
(Note 5)
-
10
-
mV
Offset after Calibration
(Note 7)
-
±100
-
µV
Offset Calibration Range
(Note 8)
-
100
-
%F.S.
-
60
-
µV/°C
Offset Drift
(Note 5,6)
TCZSE
Notes: 1. CS5321-BL is guaranteed from -55o to +85o C, CS5322-BL is guaranteed from -40o to +85o C.
2. fO = CS5322 output word rate. Refer to “CS5322 FILTER CHARACTERISTICS” on page 8 for details
on the FIR Filter.
3. Characterized with full scale input signal of 50 Hz; fo = 500 Hz.
4. Characterized with input signals of 30 Hz and 50 Hz, each 6 dB down from full scale with fo = 1000 Hz.
5. Specification is for the parameter over the specified temperature range and is for the CS5321 device
only (VREF = +4.5 V). It does not include the effects of external components; OFST = 0.
6. Drift specifications are guaranteed by design and/or characterization.
7. The offset after calibration specification applies to the effective offset voltage for a ±4.5 volt input to the
CS5321 modulator, but is relative to the output digital codes from the CS5322 after ORCAL and USEOR
have been made active.
8. The CS5322 offset calibration is performed digitally and includes ± full scale (±4.5 volts into CS5321).
Calibration of offsets greater than ±5% of full scale will begin to subtract from the dynamic range.
4
DS454F3
CS5321/22
CS5321 ANALOG CHARACTERISTICS (Continued)
CS5321
Parameter*
Symbol
Min
Typ
Max
Unit
Input Characteristics
Input Signal Frequencies
(Note 9)
BW
DC
-
1600
Hz
Input Voltage Range
(Note 10)
VIN
-4.5
-
+4.5
V
Input Overrange Voltage
(Note 10)
IOVR
-
-
5
%F.S.
-
5.5
5.5
3.0
3.0
7.5
7.5
4.5
4.5
mA
mA
mA
mA
PDN
PDL
-
55
30
75
45
mW
mW
PD
-
2
-
mW
PSR
-
60
-
dB
Power Supplies
DC Power Supply Currents
Power Consumption
(Note 11)
LPWR = 0 Positive Supplies
Negative Supplies
LPWR = 1 Positive Supplies
Negative Supplies
(Note 11)
Normal Operating Mode (Note12)
Lower Power Mode (Note 13)
Power Down
Power Supply Rejection
(dc to 128 kHz) (Note 14)
Notes: 9. The upper bandwidth limit is determined by the CS5322 digital filter.
10. This input voltage range is for the configuration shown in Figure 20, the System Connection Diagram,
and applies to signal from dc to f3 Hz. Refer to CS5322 Filter Characteristics for the values of f3.
11. All outputs unloaded. All logic inputs forced to Vdd or GND respectively.
12. LPWR = 0.
13. The CS5321 power dissipation can be reduced under the following conditions:
a) LPWR=1; MCLK=512 kHz, HBR=1
b) LWPR=1; MCLK=1.024 MHz, HBR=0
14. Characterized with a 100 mVp-p sine wave applied separately to each supply.
* Refer to Parameter Definitions (immediately following pin descriptions at the end of this data sheet).
Specifications are subject to change without notice.
DS454F3
5
CS5321/22
CS5321 SWITCHING CHARACTERISTICS (TA = (See Note 1); Vdd1, Vdd2 = 5 V ± 5%; Vss1,
Vss2 = -5 V ± 5%; Inputs: Logic 0 = 0 V Logic 1 = V+; CL = 50 pF (Note 15))
Parameter
MCLK Frequency
(Note 16)
Symbol
Min
Typ
Max
Units
fc
0.250
1.024
1.2
MHz
40
-
60
%
-
-
300
ps
MCLK Duty Cycle
MCLK Jitter (In-band)
Rise Times:
Any Digital Input
Any Digital Output
(Note 17)
trisein
triseout
-
50
100
200
ns
ns
Fall Times:
Any Digital Input
Any Digital Output
(Note 17)
tfallin
tfallout
-
50
100
200
ns
ns
MSYNC Setup Time to MCLK rising
tmss
20
-
-
ns
MSYNC Hold Time after MCLK rising
tmsh
20
-
-
ns
MCLK rising to Valid MFLG
tmfh
-
140
255
ns
MCLK rising to Valid MDATA
tmdv
-
170
300
ns
Notes: 15. Guaranteed by design, characterization, or test.
16. If MCLK is removed, the modulator will enter the power down mode.
17. Excludes MCLK input. MCLK should be driven with a signal having rise and fall times of 25 ns or faster.
t rise in
t fa llin
t rise out
t fallo ut
4.0 V
4 .6 V
1.0 V
0 .4 V
Figure 1. Rise and Fall Times
M C LK
t mss
t m sh
MSYNC
t m dv
M D A TA
t m dv
V A L ID D A TA
V A L ID D A T A
t m fh
M F LG
Figure 2. CS5321 Interface Timing, HBR=1
6
DS454F3
CS5321/22
CS5321 DIGITAL CHARACTERISTICS (TA = (See Note 1); Vdd1 = Vdd2
= 5.0 V ± 5%; GND =
0 V; measurements performed under static conditions)
Parameter
Symbol
Min
Typ
Max
Units
High-Level Input Drive Voltage
(Note 18)
VIH
(Vdd)-0.6
-
-
V
Low-Level Input Drive Voltage
(Note 18)
VIL
-
-
1.0
V
High-Level Output Voltage IOUT = -40 µA
(Note 19)
VOH
(Vdd)-0.3
-
-
V
Low-Level Output Voltage IOUT = +40 µA
(Note 19)
VOL
-
-
0.3
V
Input Leakage Current
ILKG
-
-
±10
µA
Digital Input Capacitance
CIN
-
9
-
pF
COUT
-
9
-
pF
Digital Output Capacitance
Notes: 18. Device is intended to be driven with CMOS logic levels.
19. Device is intended to be interfaced to CMOS logic. Resistive loads are not recommended on these pins.
CS5321 RECOMMENDED OPERATION CONDITIONS (Voltages with respect to GND =
0 V, See Note 20)
Parameter
DC Supply:
Ambient Operating Temperature
Symbol
Positive Vdd1,Vdd2
Negative Vss1,Vss2
-BL
TA
Min
Typ
Max
Units
4.75
-4.75
5.0
-5.0
5.25
-5.25
V
V
-55
-
+85
°C
Notes: 20. The maximum voltage differential between the Positive Supply of the CS5321 and the Positive Digital
Supply of the CS5322 must be less than 0.25 V.
CS5321 ABSOLUTE MAXIMUM RATINGS * (Voltages with respect to GND = 0 V)
Parameter
Symbol
Min
Max
Units
DC Supply:
Positive
Negative
Vdd1,Vdd2
Vss1,Vss2
-0.3
+0.3
6.0
-6.0
V
V
Input Current, Any Pin Except Supplies
(Note 21)
Iin
-
±10
mA
Output Current
Iout
-
25
mA
Total Power (all supplies and outputs)
Pt
-
1
W
Digital Input Voltage
VIND
-0.3
(Vdd)+0.3
V
Storage Temperature
Tstg
-65
150
°C
Notes: 21. Transient currents of up to 100 mA will not cause SCR latch up.
*WARNING: Operation beyond these limits may result in permanent damage to the device. Normal operation is
not guaranteed at these extremes.
DS454F3
7
CS5321/22
CS5322 FILTER CHARACTERISTICS (TA = (See Note 1); VD+ = 5.0 V; GND = 0 V;
CLKIN = 1.024 MHz; transfer function shown in Figure 3; unless otherwise specified.)
Output Word Rate
f0 (Hz)
Passband f1
(Hz)
Passband Flatness
RPB (dB)
4000
2000
1000
500
250
125
62.5
1500
750
375
187.5
93.8
46.9
23.4
0.2
0.04
0.08
0.1
0.1
0.1
0.1
-3dB Freq. f2 Stopband f3 (Hz)
(Hz)
(Note 22)
1652.5
824.3
411.9
205.9
102.9
51.5
25.7
2000
1000
500
250
125
62.5
31.25
Group Delay
(ms)
7.25
14.5
29
58
116
232
464
Notes: 22. GSB = -130 dB for all Output Word Rates.
dB
0
-3
G SB
-13 0
f1
f2
f3
f
Figure 3. CS5322 Filter Response
f0 = 62.5 Hz
Figure 4. CS5322 Digital Filter Passband Ripple
Figure 5. CS5322 Digital Filter Passband Ripple
f0 = 125 Hz
8
Figure 6. CS5322 Digital Filter Passband Ripple
f0 = 250 Hz
DS454F3
CS5321/22
Figure 7. CS5322 Digital Filter Passband Ripple
f0 = 500 Hz
Figure 8. CS5322 Digital Filter Passband Ripple
f0 = 1000 Hz
Figure 9. CS5322 Digital Filter Passband Ripple
f0 = 2000 Hz
Figure 10. CS5322 Digital Filter Passband Ripple
f0 = 4000 Hz
-5 ,2 06 ,2 5 0
-5 ,2 06,25 0
-5 ,2 12 ,5 0 0
-5 ,2 12,50 0
-5 ,2 18 ,7 5 0
-5 ,2 18,75 0
D igital O u tput C o de
D ig ital O utpu t C o d e
-5 ,2 0 8,3 28
-5 ,2 25 ,0 0 0
-5 ,2 31 ,2 5 0
-5 ,2 4 0 ,7 2 3
-5 ,2 25,00 0
-5 ,2 31,25 0
-5 ,2 37 ,5 0 0
-5 ,2 37,50 0
-5 ,2 43 ,7 5 0
-5 ,2 43,75 0
-5 ,2 50 ,0 0 0
-5 ,2 50,00 0
1
8
15
22
29
36
43
T im e (# o f O u tp u t W o rd s)
Figure 11. CS5322 Impulse Response,
f0 = 62.5 Hz
DS454F3
50
57
1
8
15
22
29
36
43
50
57
T im e (# o f O utp u t W o rd s)
Figure 12. CS5322 Impulse Response,
f0 = 1000 Hz
9
CS5321/22
CS5322 POWER SUPPLY (TA = (See Note 1); VD+ = 5 V; CLKIN = 1.024 MHz)
CS5322-BL
Parameter
Power Supply Current:
ID+
Power Dissipation:
Min
Typ
Max
Unit
(Note 11)
-
2.2
4
mA
(Note 11)
PWDN Low
PWDN High
-
11
0.6
20
2.5
mW
mW
CS5322 SWITCHING CHARACTERISTICS (TA = (See Note 1); VD+ = 5 V ± 5%; DGND = 0 V;
Inputs: Logic 0 = 0 V Logic 1 = VD+; CL = 50 pF (Note 23)
Parameter
Symbol
Min
Typ
Max
Units
fc
0.512
1.024
1.2
MHz
40
-
60
%
CLKIN Frequency
CLKIN Duty Cycle
Rise Times:
Any Digital Input
Any Digital Output
trise
-
50
100
100
ns
ns
Fall Times:
Any Digital Input
Any Digital Output
tfall
-
50
100
100
ns
ns
DRDY to Data Valid
tddv
-
-
25
ns
RSEL Setup Time before Data Valid
trss
50
-
-
ns
Read Setup before CS Active
trsc
20
-
-
ns
Read Active to Data Valid
trdv
-
-
50
ns
SCLK rising to New SOD bit
trdd
-
-
50
ns
SCLK Pulse Width High
trph
30
-
-
ns
SCLK Pulse Width Low
trpl
30
-
-
ns
SCLK Period
trsp
100
-
-
ns
SCLK falling to DRDY falling
trst
-
-
50
ns
CS High to Output Hi-Z
trch
-
-
20
ns
Read Hold Time after CS Inactive
trhc
20
-
-
ns
Read Select Setup to SCLK falling
trds
20
-
-
ns
Write Setup Before CS Active
twsc
20
-
-
ns
SCLK Pulse Width Low
twpl
30
-
-
ns
SCLK Pulse Width High
twph
30
-
-
ns
SCLK Period
twsp
100
-
-
ns
Write Setup Time to First SCLK falling
twws
20
-
-
ns
Data Setup Time to First SCLK falling
twds
20
-
-
ns
Write Select Hold Time after SCLK falling
twwh
20
-
-
ns
Write Hold Time after CS Inactive
twhc
20
-
-
ns
Data Hold Time after SCLK falling
twdh
20
-
-
ns
Serial Port Read Timing
Serial Port Write Timing
23. Guaranteed by design, characterization and/or test.
10
DS454F3
CS5321/22
t rss
RSEL
DRDY
t ddv
t rst
R /W
t rsc
t rhc
CS
t rch
t rdv
SOD
H i-Z
M S B -1
MSB
LSB
LS B + 1
H i-Z
t rdd
S C LK
t rph
t rpl
t rsp
t rds
Serial Port Read Timing
(R/W = 1, CS = 0, RSEL = 1 DRDY Does not toggle if reading status, RSEL = 0)
CS
t whc
t w sc
R /W
t wph
t wws
t wwh
SCLK
t w sp
t wdh
t wds
S ID
MSB
M S B -1
t wpl
LS B+1
LSB
Serial Port Write Timing
Figure 13. CS5322 Serial Port Timing
DS454F3
11
CS5321/22
CS5322 SWITCHING CHARACTERISTICS (continued)
Parameter
Symbol
Min
Typ
Max
Units
SYNC Setup Time to CLKIN rising
tss
20
-
-
ns
SYNC Hold Time after CLKIN rising
tsh
20
-
-
ns
TDATA Setup Time to CLKIN rising after SYNC
ttds
-
20
-
ns
TDATA Hold Time after CLKIN rising
ttdh
-
150
-
ns
ORCAL Setup Time to CLKIN rising
tos
20
-
-
ns
ORCAL Hold Time after CLKIN rising
toh
20
-
-
ns
Test Data (TDATA) Timing
DRDY Timing
CLKIN rising to DRDY falling
tdf
-
140
-
ns
CLKIN falling to DRDY rising
tdr
-
150
-
ns
CLKIN rising to ERROR change
tec
-
140
-
ns
RESET Setup Time to CLKIN rising
trs
20
-
-
ns
RESET Hold Time after CLKIN rising
trh
20
-
-
ns
SYNC Setup Time to CLKIN rising
tss
20
-
-
ns
SYNC Hold Time after CLKIN rising
tsh
20
-
-
ns
RESET Timing
C L K IN
t sh
t ss
SYNC
t oh
t os
ORCAL
LSYN C*
t td s
TDA TA
t rd h
V A L ID
t td s
t td h
V A L ID
F IL T E R
SA MPLES
DA TA
Figure 14. TDATA Setup/Hold Timing
12
DS454F3
CS5321/22
C L K IN
SYNC
LSYN C *
t dr
t df
DRDY
t ec
ERROR
*N o te : F o r o v e rw rite c a s e , D R D Y w ill re m a in h ig h .
Figure 15. DRDY Timing
C LK IN
t rs
t rh
RESET
t ss
t sh
SYNC
Figure 16. RESET Timing
DS454F3
13
CS5321/22
CS5322 SWITCHING CHARACTERISTICS (continued)
Parameter
MCLK Frequency
(Note 24)
Symbol
Min
Typ
Max
Units
fc
0.512
1.024
1.1
MHz
40
-
60
%
MCLK Duty Cycle
Rise Times:
Any Digital Input
Any Digital Output
(Note 25)
trise
-
50
100
200
ns
ns
Fall Times:
Any Digital Input
Any Digital Output
(Note 25)
tfall
-
50
100
200
ns
ns
SYNC Setup Time to CLKIN rising
tss
20
-
-
ns
SYNC Hold Time after CLKIN rising
tsh
20
-
-
ns
CLKIN edge to MCLK edge
tmss
-
30
-
ns
MCLK rising to Valid MDATA
tmsh
-
50
-
ns
tmsd
-
90
-
ns
MSYNC Delay from MCLK rising
(Note 26)
Notes: 24. If MCLK is removed, the modulator will enter the power down mode.
25. Excludes MCLK input. MCLK should be driven with a signal having rise and fall times of 25 ns or faster.
26. Only the rising edge of MSYNC relative to MCLK is used to synchronize the device. MSYNC can return
low at any time as long as it remains high for at least one MCLK cycle.
C L K IN
t sh
t ss
SYNC
LSYN C*
t m ss
M C LK
t m sd
t m sd
MSYNC
t m sh
t m sh
V A L ID D A T A
M DATA
V A L ID D A T A
F IL T E R
SA M PLES
DATA
M FLG
* In te rn a l tim in g s ig n a l g e n e ra te d in th e C S 5 3 2 2
Figure 17. CS5321/CS5322 Interface Timing
14
DS454F3
CS5321/22
CS5322 DIGITAL CHARACTERISTICS (TA = (See Note 1); VD+ = 5.0 V ± 5%; GND = 0 V;
measurements performed under static conditions)
Parameter
Symbol
Min
Typ
Max
Units
High-Level Input Drive Voltage
VIH
(VD+)-0.3
-
-
V
Low-Level Input Drive Voltage
VIL
-
-
0.3
V
High-Level Input Threshold
(Note 27)
(VD+)-1.0
-
-
V
Low-Level Input Threshold
(Note 27)
-
-
1.0
V
High-Level Output Voltage IOUT = -40µA
(Note 28)
VOH
(VD+)-0.6
-
-
V
Low-Level Output Voltage IOUT = +1.6 mA
(Note 28)
VOL
-
-
0.4
V
Input Leakage Current
ILKG
-
-
±10
µA
Three-State Leakage Current
All pins except MFLG, SOD
IOZ
-
-
±10
µA
Digital Input Capacitance
CIN
-
9
-
pF
COUT
-
9
-
pF
Digital Output Capacitance
Notes: 27. Device is intended to be driven with CMOS logic levels.
28. Device is intended to be interfaced to CMOS logic. Resistive loads are not recommended on these pins.
CS5322 RECOMMENDED OPERATION CONDITIONS (Voltages with respect to GND =
0 V)
Parameter
DC Supply:
Symbol
Min
Typ
Max
Units
VD+
VD-
4.75
-4.75
5.0
-5.0
5.25
-5.25
V
V
TA
-40
-
+85
°C
(Note 29)
Positive
Negative
Ambient Operating Temperature
-BL
Notes: 29. The maximum voltage differential between the Positive Supply of the CS5321 and the Positive Digital
Supply of the CS5322 must be less than 0.25 V.
CS5322 ABSOLUTE MAXIMUM RATINGS * (Voltages with respect to GND = 0 V)
Parameter
Symbol
Min
Typ
Max
Units
VD+
VD-
-0.3
0.3
-
(VD+)+0.3
-6.0
V
V
Iin
-
-
±10
mA
Digital Input Voltage
VIND
-0.3
-
(VD+)+0.3
V
Storage Temperature
Tstg
-65
-
150
°C
DC Supply:
(Note 29)
Positive
Negative
Input Current, Any Pin Except Supplies
(Note 30)
Notes: 30. Transient currents of up to 100 mA will not cause SCR latch up.
*WARNING: Operation beyond these limits may result in permanent damage to the device. Normal operation is
not guaranteed at these extremes.
DS454F3
15
CS5321/22
2. GENERAL DESCRIPTION
The CS5321 is a fourth-order CMOS monolithic
analog modulator designed specifically for very
high resolution measurement of signals between dc
and 1600 Hz. Configuring the CS5321 with the
CS5322 FIR filter results in a high resolution A/D
converter system that performs sampling and A/D
conversion with a dynamic range exceeding 120
dB.
The CS5321 uses a fourth-order oversampling architecture to achieve high resolution A/D conversion. The modulator consists of a 1-bit A/D
converter embedded in a negative feedback loop.
The modulator provides an oversampled serial bit
stream at 256 kbits per second (HBR=1) and 128
kbits per second (HBR=0) operating with a clock
rate of 1.024 MHz. Figure 18 illustrates the
CS5321 block diagram.
Vdd1
Vss1
AGND
Osc.
The CS5322 is a monolithic digital Finite Impulse
Response (FIR) filter with programmable decimation. The CS5322 and CS5321 are intended to be
used together to form a unique high dynamic range
ADC chipset. The CS5322 provides the digital
anti-alias filter for the CS5321 modulator output.
The CS5322 consists of: a multi-stage FIR filter,
four registers (status, data, offset, and configuration), a flexible serial input and output port, and a
2-channel input data multiplexer that selects data
from the CS5321 (MDATA) or user test data
(TDATA). The CS5322 decimates (64x to 4096x)
the output to any of seven selectable up-date periods: 16, 8, 4, 2, 1, 0.5 and 0.25 milliseconds. Data
is output from the digital filter in a 24-bit serial format. Figure 19 illustrates the CS5322 Block Diagram.
Vdd2
Vss2
DGND
Digital
LPWR
Control
OFST
Detect
MFLG
AINR
AIN+
AIN-
Σ
HBR
Clock
A/D
Generation
MCLK
MSYNC
MDATA
D/A
MDATA
VREF+
VREF-
Figure 18. CS5321 Block Diagram
16
DS454F3
CS5321/22
S ID
CSEL
PW DN
ORCAL
USEOR
DECC
DECB
DECA
H /S
SCLK
C L K IN
RESET
SYNC
CS
R /W
M FLG
TDATA
M D ATA
DATA M UX
C O N F IG R E G
C O N F IG M U X
F IR 1
F IR 2
CONTROL
DRDY
ERROR
MSYNC
M C LK
F IR 3
DATA REG
STATUS R EG
B IT S E L E C T
RSEL
B IT S E L E C T
MUX
SOD
Figure 19. CS5322 Block Diagram
DS454F3
17
CS5321/22
2.1 Analog Input
The CS5321 modulator uses a switched capacitor
architecture for its signal and voltage reference inputs. The signal input uses three pins; AINR, AIN+,
and AIN-. The AIN- pin acts as the return pin for
the AINR and AIN+ pins. The AINR pin is a
switched capacitor "rough charge" input for the
AIN+ pin. The input impedance for the rough
charge pin (AINR) is 1/fC where f is two times the
modulator sampling clock rate and C is the internal
sampling capacitor (about 40 pF). Using a 1.024
MHz master clock (HBR = 1) yields an input impedance of about 1/(512 kHz)X(40 pF) or about 50
kΩ. Internal to the chip the rough charge input precharges the sampling capacitor used on the AIN+
input, therefore the effective input impedance on
the AIN+ pin is orders of magnitude above the impedance seen on the AINR pin.
The analog input structure inside the VREF+ pin is
very similar to the AINR pin but includes additional circuitry whose operating current can change
over temperature and from device to device. Therefore, if gain accuracy is important, the VREF+ pin
should be driven from a low source impedance.
The current demand of the VREF+ pin will produce
a voltage drop of approximately 45 mV across the
200 Ω source resistor of Figure 20 and Figure 21
Option A with MCLK = 1.024 MHz, HBR = 1, and
temperature = 25°C.
When the CS5321 modulator is operated with a 4.5
V reference it will accept a 9 V p-p input signal, but
modulator loop stability can be adversely affected
by high frequency out-of-band signals. Therefore,
input signals must be band-limited by an input filter. The -3 dB corner of the input filter must be
equal to the modulator sampling clock divided by
64. The modulator sampling clock is MCLK/4
when HBR = 1 or MCLK/8 when HBR = 0. With
MCLK = 1.024 MHz, HBR = 1, the modulator
sampling clock is 256 kHz which requires an input
filter with a -3 dB corner of 4 kHz. The bandlimit-
18
ing may be accomplished in an amplifier stage
ahead of the CS5321 modulator or with the RC input filter at the AIN+ and AINR input pins. The RC
filter at the AIN+ and AINR pins is recommended
to reduce the "charge kick" that the driving amplifier sees as the switched capacitor sampling is performed.
Figure 20 illustrates the CS5321 and CS5322 system connections. The input components on AINR
and AIN+ should be identical values for optimum
performance. In choosing the components the capacitor should be a minimum of 0.1 µF (C0G dielectric ceramic preferred). For minimum board
space, the RC components on the AINR input can
be removed, but this will force the driving amplifier to source the full dynamic charging current of
the AINR input. This can increase distortion in the
driving amplifier and reduce system performance.
In choosing the RC filter components, increasing C
and minimizing R is preferred. Increasing C reduces the instantaneous voltage change on the pin, but
may require paralleling capacitors to maintain
smaller size (the recommended 0.1 µF C0G ceramic capacitor is larger than other similar-valued capacitors with different dielectrics). Larger resistor
values will increase the voltage drop across the resistor as the recharging current charges the
switched capacitor input.
2.2 The OFST Pin
The CS5321 modulator can produce "idle tones"
which occur in the passband when the input signal
is steady state dc signal within about
±50 mV of bipolar zero. In the CS5321 these tones
are about 135 dB down from full scale. The user
can force these idle tones "out-of-band" by adding
100 mV of dc offset to the signal at the AIN input.
Alternately, if the user circuitry has a low offset
voltage such that the input signal is within ±50 mV
of bipolar zero when no AC signal is present, the
OFST pin on the CS5321 can be activated. When
OFST = 1, +100 mV of input referred offset will be
DS454F3
CS5321/22
added internal to the CS5321 and guarantee that
any idle tones present will lie out-of-band. The user
should be certain that when OFST is active (OFST
=1) that the offset voltage generated by the user circuitry does not negate the offset added by the
OFST pin.
2.3 Input Range and Overrange
Conditions
The analog input is applied to the AIN+ and AINR
pins with the AIN- pin connected to GND. The input is fully differential but for proper operation the
AIN- pin must remain at GND potential.
The analog input span is defined by the voltage applied between the VREF+ and VREF- input pins.
+5V
Analog
Supply
10 µ F
+
0.1 µ F 2
1
Vdd1
GND1
The modulator is a fourth order delta-sigma and is
therefore conditionally stable. The modulator may
go into an oscillatory condition if the analog input
is overranged. Input signals which exceed either
plus or minus full scale by more than 5 % can introduce instability in the modulator. If an unstable
condition is detected, the modulator will be reduced to a first order system until loop stability is
achieved. If this occurs the MFLG pin will transition from a low to a high and result in an error bit
being set in the CS5322. The input signal must be
reduced to within the full scale range of the converter for at least 32 MCLK cycles for the modulator to recover from this error condition.
+5 V
Digital
Supply
0.1 µ F
22
Vdd2
See the Voltage Reference section of this data sheet
for voltage reference requirements.
23
0.01 µF 20
21
VD+
GND11
DGND
25
SID
OFST
LPWR
+4.5V
VREF
200 Ω
HBR
5
VREF+
+ 68 µF
0.1 µF
TANT.
Control
26
Logic
SCLK
25
MFLG
6
24
9
0.1 µ F
COG
12
11
7
4
0.1 µF
+
RSEL
MCLK
Test
Data
11
12
13
PWDN
TDATA
USEOR
ORCAL
GND6
GND8
GND4
GND3
GND2
Vss1
3
15
16
GND9
DECA
3
Clock
Source
CLKIN
DECB
SYNC
DECC
2
19
V ss2
VD+
0.1 µ F
14
15
19
18
Hardware
Control
17
16
4
RESET
GND10
21
23
CSEL
GND7
GND5
Interface
ERROR
CS5322
17
Data
27
MFLG
MDATA
MDATA
Serial
22
DRDY
H/S
AIN-
13
R/W
MSYNC
10
MDATA
8
1
28
CS5321
AIN+
14
7
18
AINR
0.1 µ F
COG
26
CS
5
MCLK
10
402 Ω
10 µF
27
20
402 Ω
-5V
Analog
Supply
SOD
MSYNC
6
VREF-
Signal
Source
24
28
+5 V
Digital
Supply
8
DGND
0.01 µF
9
Unused logic
inputs must be
connected to
DGND or VD+
Figure 20. System Connection Diagram
DS454F3
19
CS5321/22
2.4 Voltage Reference
The CS5321 is designed to operate with a voltage
reference in the range of 4.0 to 4.5 Volts. The voltage reference is applied to the VREF+ pin with the
VREF- pin connected to the GND. A 4.5 V reference will result in the best S/N performance but
most 4.5 V references require a power supply voltage greater than 5.0 V for operation. A 4.0 V reference can be used for those applications which must
operate from only 5.0 V supplies, but will yield a
S/N slightly lower (1-2 dB) than when using a 4.5
V reference. The voltage reference should be designed to yield less than 2 µVrms of noise in band
at the VREF+ pin of the CS5321. The CS5322 filter
selection will determine the bandwidth over which
the voltage reference noise will affect the
CS5321/22 dynamic range.
For a 4.5 V reference, the LT1019-4.5 voltage reference yields low enough noise if the output is filtered with a low pass RC filter as shown in Figure
21 Option A. The filter in Figure 21 Option A is acceptable for most spectral measurement applications, but a buffered version with lower source
impedance (Figure 21 Option B) may be preferred
+ 9 to
15V
10 Ω
for dc-measurement applications. Due to its dynamic (switched-capacitor) input the input impedance of the +VREF pin of the CS5321 will change
any time MCLK or HBR is changed. Therefore the
current required from the voltage reference will
change any time MCLK or HBR is changed. This
can affect gain accuracy due to the high source impedance of the filter resistor in Figure 20 and Figure 21 Option A. If gain error is to be minimized,
especially when MCLK or HBR is changed, the
voltage reference should have lower output impedance. The buffer of Figure 21 Option B offers lower
output impedance and will exhibit better system
gain stability.
2.5 Clock Source
For proper operation, the CS5321 must be provided
with a CMOS-compatible clock on the MCLK pin.
The MCLK for the CS5321 is usually provided by
the CS5322 filter. MCLK is usually 1.024 MHz to
set the seven selectable output word rates from the
CS5322. The MCLK frequency can be as low as
250 kHz and as high as 1.2 MHz. The choice of
clock frequency can affect performance; see the
Performance section of the data sheet. The clock
Option A
200 Ω
0.1 µ F
0.1 µ F
L T 1 0 1 9 -4 .5
+ 9 to 1 5 V
Option B
1k Ω
4 9 .9 Ω
+
10k Ω
To VRE F+
+ 68 µ F
+
+
100 µ F
AL
100 µ F
AL
100 Ω
0.1 µ F
-
1k Ω
+
68 µ F
T ant
To VRE F+
LT 1007
Figure 21. 4.5 Voltage Reference with two filter options
20
DS454F3
CS5321/22
must have less than 300 ps jitter to maintain data
sheet performance from the device. The CS5321 is
equipped with loss of clock detection circuitry
which will cause the CS5321 to enter a powereddown state if the MCLK is removed or reduced to
a very low frequency. The HBR pin on the CS5321
modifies the sampling clock rate of the modulator.
When HBR = 1, the modulator sampling clock will
be at MCLK/4; with HBR = 0 the modulator sampling clock will be at MCLK/8. The chip set will exhibit about 3 dB less S/N performance when the
HBR pin is changed from a logic "1" to a logic "0"
for the same output word rate from the CS5322.
2.6 Low Power Mode
The CS5321 includes a low power operating mode
(LPWR =1). When operated with LPWR = 1, the
CS5321 modulator sampling clock must be restricted to rates of 128 kHz or less. Operating in low
power mode with modulator sample rates greater
than 128 kHz will greatly degrade performance.
2.7 Digital Interface and Data Format
The MCLK signal (normally 1.024 MHz) is divided by four, or by eight inside the CS5321 to generate the modulator oversampling clock. The HBR
pin determines whether the clock divider inside the
CS5321 divides by four (HBR =1) or by eight
(HBR = 0). The modulator outputs a ones density
bit stream from its MDATA and MDATA pins proportional to the analog input signal, but at a bit rate
determined by the modulator over sampling clock.
For proper synchronization of the bitstream, the
DS454F3
CS5321 must be furnished with an MSYNC signal
prior to data conversion. The MSYNC signal, generated by the CS5322, resets the MCLK counter-divider in the CS5321 to the correct phase so that the
bitstream can be properly sampled by the CS5322
digital filter.
When operated with the CS5322 digital filter the
output codes from the CS5321/22 will range from
approximately decimal -5,242,880 to +5,242,879
for an input to the CS5321 of ±4.5 V. Table 1 illustrates the output coding for various input signal amplitudes. Note that with a signal input defined as a
full scale signal (4.5 V with VREF+ = 4.5 V) the
CS5321/22 chipset does not output a full scale digital code of 8,388,607 but is scaled to a lower value
to allow some overrange capability. Input signals
can exceed the defined full scale by up to 5% and
still be converted properly.
Modulator Input
Signal
> (+VREF + 5%)
CS5322 Filter
Output Code
HEX
Decimal
Error Flag Possible
≈ (+VREF + 5%)
53FFFF(H)
+5505023
+VREF
4FFFFF(H)
+5242879
0V
000000(H)
0
-VREF
B00000(H)
-5242880
≈ - (+VREF +5%)
AC0000(H)
-5505024
> - (+VREF +5%)
Error Flag Possible
Table 1. Output Coding for the CS5321 and
CS5322 Combination
21
CS5321/22
2.8 Performance
0
Figure 22, 23 and 24 illustrate the spectral performance of the CS5321/22 and chipset when operating from a 1.024 MHz master clock. Ten 1024
point FFTs were averaged to produce the plots.
-20
Figure 22 illustrates the chip set with a 100 Hz,
-20 dB input signal. The sample rate was set at 1
kHz. Dynamic range is 122 dB.
-100
The dynamic range calculated by the test soft-ware
is reduced somewhat in Figures 23 and 24 because
of jitter in the signal test oscillator. Jitter in the
100 Hz signal source is interpreted by the signal
processing software to be increased noise.
-180
The choice of master clock frequency will affect
performance. The CS5321 will exhibit the best Signal to Distortion performance with slower modulator sampling clock rates as slower sample rates
allow more time for amplifier settling.
For lowest offset drift, the CS5321 should be operated with MCLK = 1.024 MHz and HBR = 1. Slower modulator sampling clock rates will exhibit
more offset drift. Changing MCLK to 512 kHz
(HBR = 1) or changing HBR to zero (MCLK =
1.024 MHz) will cause the drift rate to double. Offset drift is not linear over temperature so it is difficult to specify an exact drift rate. Offset drift
characteristics vary from part to part and will vary
as the power supply voltages vary. Therefore, if the
CS5321 is to be used in precision dc measurement
applications where offset drift is to be minimized,
the power supplies should be well regulated. The
CS5321 will exhibit about 6 ppm/°C of offset drift
with MCLK = 1 and HBR = 1. Gain drift of the
CS5321 itself is about 5 ppm/°C and is not affected
by either modulator sample rate or by power supply
variation.
D yn a m ic R a n g e = 1 2 2 .0 d B
HBR = 1
OFST = 0
LPW R = 0
-40
-60
-80
-120
-140
-160
0
500
Figure 22. 1024 Point FFT Plot with -20 dB Input, 100 Hz
Input, ten averages
0
S /D = 1 1 6 .0 d B
S /N = 1 1 8 .4 d B
S /N + D = 1 1 4 .2 d B
HBR = 1
OFST = 0
LPW R = 0
-20
-40
-60
-80
-100
see text
-120
-140
-160
-180
0
500
Figure 23. 1024 Point FFT Plot with Full Scale Input,
100 Hz Input, HBR = 1, ten averages
0
S /D = 1 2 2 .7 d B
S /N = 1 1 7 .1 d B
S /N + D = 1 1 6 .4 d B
HBR = 0
OFST = 0
LPW R = 0
-20
-40
-60
-80
-100
see text
-120
-140
-160
-180
0
500
Figure 24. 1024 Point FFT Plot with Full Scale Input,
100 Hz Input, HBR = 0, ten averages
22
DS454F3
CS5321/22
2.9 Power Supply Considerations
2.11 RESET Operation
The system connection diagram, Figure 20, illustrates the recommended power supply arrangements. There are two positive power supply pins
for the CS5321 and two negative power supply
pins. Power must be supplied to all four pins and
each of the supply pins should be de-coupled with
a 0.1 µF capacitor to the nearest ground pin on the
device.
The RESET pin puts the CS5322 into a known initialized state. RESET is recognized on the next
CLKIN rising edge after the RESET pin has been
brought high (RESET=1). All internal logic is initialized when RESET is active.
When used with the CS5322 digital filter, the maximum voltage differential between the positive supplies of the CS5321 and the positive digital supply
of the CS5322 must be less than 0.25 V. Operation
beyond this constraint may result in loss of analog
performance in the CS5321/22 system performance.
Many seismic or portable data acquisition systems
are battery powered and utilize dc-dc converters to
generate the necessary supply voltages for the system. To minimize the effects of power supply interference, it is desirable to operate the dc-dc
converter at a frequency which is rejected by the
digital filter, or locked to the modulator sample
clock rate.
A synchronous dc-dc converter, whose operating
frequency is derived from the 1.024 MHz clock
used to drive the CS5322, will minimize the potential for "beat frequencies" appearing in the passband between dc and the corner frequency of the
digital filter.
2.10 Power Supply Rejection Ratio
The PSRR of the CS5321 is frequency dependent.
The CS5322 digital filter attenuation will aid in rejection of power supply noise for frequencies
above the corner frequency setting of the CS5322.
For frequencies between dc and the corner frequency of the digital filter, the PSRR is nearly constant
at about 60 dB.
DS454F3
Normal device operation begins on the second
CLKIN rising edge after RESET is brought low.
The CS5322 will remain in an idle state, not performing convolutions, until triggered by a SYNC
event.
A RESET operation clears memory, sets the data
output register, offset register, and status flags to all
zeroes, and sets the configuration register to the
state of the corresponding hardware pins (PWDN,
ORCAL, DECC, DECB, DECA, USEOR, and
CSEL). The reset state is entered on power on, independent of the RESET pin. If RESET is low, the
first CLKIN will exit the power on reset state.
2.12 Power-down Operation
The PWDN pin puts the CS5322 into the powerdown state. The power-down state is entered on the
first CLKIN rising edge after the PWDN pin is
brought high. While in the power-down state, the
MCLK and MSYNC signals to the CS5321 analog
modulator are held low. The loss of the MCLK signal to the modulator causes it to power-down. The
signals on the MDATA and MFLG pins are ignored. The serial interface of the CS5322 remains
active allowing read and write operations. Information in the data register, offset register, configuration register, and convolution data memory are
maintained during power-down. The internal controller requires 64 clock cycles after PWDN is asserted before CLKIN stops.
The CS5322 exits the power-down state on the first
CLKIN rising edge after the PWDN pin is brought
low. The CS5322 then enters an idle state until triggered by a SYNC event.
23
CS5321/22
To avoid possible high current states while in the
power down state, the following conditions apply:
1) CLKIN must be active for at least 64 clock cycles after PWDN entry.
2) CSEL and TDATA must not both be asserted
high.
2.13 SYNC Operation
The SYNC pin is used to start convolutions and
synchronize the CS5322 and CS5321 to an external
sampling source or timing reference. The SYNC
event is recognized on the first CLKIN rising edge
after the SYNC pin goes high. SYNC may remain
high indefinitely. Only the sequence of SYNC rising followed by CLKIN rising generates a SYNC
event.
The SYNC event aligns the output sample and
causes the filter to begin convolutions. The first
SYNC event causes an immediate DRDY provided
DRDY is low. Subsequent data ready events will
occur at a rate determined by the decimation rate
inputs DECC, DECB, and DECA. Multiple SYNC
events can be applied with no effect on operation if
they are perfectly timed according to the decimation rate. Any SYNC event not in step with the decimation rate will cause a realignment and loss of
data.
2.14 Serial Read Operation
Serial read is used to obtain status or conversion
data. The CS, R/W, SCLK, RSEL, and SOD pins
control the read operation. The serial read operation is activated when CS goes low (CS=0) with the
R/W pin high (R/W=1). The RSEL pin selects between conversion data (data register) or status information (status register). The selected serial bit
stream is output on the SOD (Serial Output Data)
pin.
On read select, SCLK can either be high or low, the
first bit appears on the SOD pin and should be
latched on the falling edge of SCLK. After the first
24
SCLK falling edge, each SCLK rising edge shifts
out a new bit. Status reads are 16 bits, and data
reads are 24 bits. Both streams are supplied as MSB
first, LSB last.
In the event more SCLK pulses are supplied than
necessary to clock out the requested information,
trailing zeroes will be output for data reads and
trailing LSB’s for status reads. If the read operation
is terminated before all the bits are read, the internal bit pointer is reset to the MSB so that a re-read
will give the same data as the first read, with one
exception. The status error flags are cleared on read
and will not be available on a re-read.
The status error flags must be read before entering
the power-down state. If an error has occurred before entering powerdown and the status bit (ERROR) has not been read, the status bits (ERROR,
OVERWRITE, MFLG, ACC1 and ACC2) may not
be cleared on status reads. Upon exiting the powerdown state and entering normal operation, the user
may be flagged that an error is still present.
The SOD pin floats when read operation is deactivated (R/W=1, CS=1). This enables the SID and
SOD pins to be tied together to form a bi-directional serial data bus. There is an internal nominal
100 kΩ pull-up resistor on the SOD pin.
2.15 Serial Write Operation
Serial write is used to write data to the configuration register. The CS, R/W, SCLK and SID pins
control the serial write operation. The serial write
operation is activated when CS goes low (CS=0)
with R/W pin low (R/W=0).
Serial input data on the SID pin is sampled on the
falling edge of SCLK. The input bits are stored in a
temporary buffer until either the write operation is
terminated or 8 bits have been received. The data is
then parallel loaded into the configuration register.
If fewer than 8 bits are input before the write termination, the other bits may be indeterminate.
DS454F3
CS5321/22
Note that a write will occur when CS = 0 and R/W
= 0 even if SCLK is not toggled. Failure to clock in
data with the appropriate number of SCLKs can
leave the configuration register in an indeterminate
condition.
The serial bit stream is received MSB first, LSB
last. The order of the input control data is PWDN
first, followed by ORCAL, USEOR, CSEL, Reserved, DECC, DECB, and DECA. The configuration data bits are defined in Table 2. The
configuration data controls device operation only
when in the software mode, i.e., the H/S pin is low
(H/S = 0). The Reserved configuration data bit
must always be written low.
2.16 Offset Calibration Operation
The offset calibration routine computes the offset
produced by the CS5321 modulator and stores this
value in the offset register. The USEOR pin or bit
determines if the offset register data is to be used to
correct output words.
After power is applied to the chip set the CS5322
must be RESET. To begin an offset calibration, the
CS5321 analog input must represent the offset value. Then in software mode (H/S = 0) the ORCAL
bit must be toggled from a low to a high. In hardware mode the ORCAL pin must be toggled low
for at least one CLKIN cycle, then taken high (ex-
Input Bit #
cept when ORCAL = 1 and the CS5322 is RESET
as this toggles the ORCAL internally). After ORCAL has been toggled, the SYNC signal must be
applied to the CS5322. The filter settles on the input value in 56 output words. The output word rate
is determined by the state of the decimation rate
control pins, DECC, DECB, and DECA. On the
57th output word, the CS5322 issues the ORCALD status flag, outputs the offset data sample,
and internally loads the offset register. During calibration, the offset register value is not used.
If USEOR is high (USEOR=1), subsequent samples will have the offset subtracted from the output.
The state of USEOR must remain high for the complete duration of the convolution cycle. If USEOR
is low (USEOR=0), the output word is not corrected, but the offset register retains its value for later
use. The results of the last calibration will be held
in the offset register until the end of a new calibration, or until the CS5322 is reset using the RESET
pin. USEOR does not alter the offset register value,
only its usage.
To restart a calibration, ORCAL and SYNC must
be taken low for at least one CLKIN cycle. ORCAL must then be taken high. The calibration will
restart on the next SYNC event. If the ORCAL pin
remains in a high state, only a single calibration
will start on the first SYNC signal.
Equivalent Hardware
Function
Description
1 (MSB)
PWDN
Standby mode
2
ORCAL
Self-offset calibration
3
USEOR
Use Offset Register
4
CSEL
Channel Select
5
Reserved
Factory use only
6
DECC
Filter BW selection
7
DECB
Filter BW selection
8 (LSB)
DECA
Filter BW selection
Table 2. Configuration Data Bits
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CS5321/22
2.17 Status Bits
The Status Register is a 16-bit register which allows the user to read the flags and configuration
settings of the CS5322. Table 3 documents the data
bits of the Status Register.
The ERROR bit and ERROR pin value are the
OR’ed result of OVERWRITE, MFLG, ACC1, and
ACC2. The ERROR bit is active high whenever
any of the four error bits are set due to a fault condition. The ERROR pin output is active low and
has a nominal 100 kΩ internal pull-up resistor.
The OVERWRITE bit is set when new conversion
data is ready to be loaded into the data register, but
the previous data was not completely read out. This
can occur on either of two conditions: a read operation is in progress or a read operation was started,
then aborted, and not completed. These two conditions are data read attempts. The attempt is identified by the first SCLK low edge (MSB read) of a
data register read. If a data register read is not at-
Output Bit #
tempted, the CS5322 assumes that data is not wanted and does not assert OVERWRITE, and the old
data is over-written by the new data. On an OVERWRITE condition, the old partially read data is preserved, and the new data word is lost.
Status reads have no effect on OVERWRITE assert
operations. The OVERWRITE bit is cleared on a
status register read or RESET.
The MFLG error bit reflects the CS5321 MFLG
signal. Any high level on the CS5322 MFLG pin
will set the MFLG status bit. The bit is cleared on a
status register read or RESET operation, only if the
MFLG pin on the CS5322 has returned low. A internal nominal 100 kΩ pulldown resistor is on the
MFLG pin.
The accumulator error bits, ACC1 and ACC2, indicate that an underflow or overflow has occurred in
the FIR1 filter for ACC1, or the FIR2 and FIR3 filters for ACC2. Both errors are cleared on a status
read, provided the error conditions are no longer
Function
Description
1 (MSB)
Error
Detects one of the errors below
2
OVERWRITE Error
Overwrite Error
3
MFLG Error
Modulator Flag Error
4
ACC1 Error
Accumulator 1 Error
5
ACC2 Error
Accumulator Error
6
DRDY
Data Ready
7
1SYNC
First sample after SYNC
8
ORCALD
Offset calibration done
9
PWDN
Standby mode
10
ORCAL
Self-offset Calibration
11
USEOR
Use Offset Register
12
CSEL
Channel Select
13
Reserved
Factory use only
14
DECC
Bandwidth Selection Status
15
DECB
Bandwidth Selection Status
16
DECA
Bandwidth Selection Status
Table 3. Status Data (from the SOD Pin)
26
DS454F3
CS5321/22
present. In normal operation the ACC1 error will
only occur when the input data stream to FIR1 is all
1’s for more than 32 bits. The ACC2 error cannot
occur in normal operation.
The DRDY bit reflects the state of the DRDY pin.
DRDY rising edge indicates that a new data word
has been loaded into the data register and is available for reading. DRDY will fall after the SCLK
falling edge that reads the data register LSB. If nodata read attempt is made, DRDY will pulse low
for 1/2 CLKIN cycle, providing a positive edge on
the new data availability. In the OVERWRITE
case, DRDY remains high because new data is not
loaded at the normal end of conversion time.
able in the output register. This flag is high only
during that sample and is otherwise low.
The remaining five status bits (PWDN, ORCAL,
USEOR, CSEL, Reserved, DECC, DECB, and DECA) provide configuration readback for the user.
These bits echo the control source for the CS5322
such that in the hardware mode (H/S=1), they follow the corresponding input pins. In host mode
(H/S=0) they follow the corresponding configuration bits.
A brief explanation of the eight bits are as follows:
PWDN - When high, indicates that the CS5322 is in
the power-down state.
The 1SYNC status bit provides an indication of the
filter group delay. It goes high on the second output
sample after SYNC and is valid for only that sample. For repetitive SYNC operations, SYNC must
run at one fourth the output word rate or slower to
avoid interfering with the 1SYNC operation. With
these slower repetitive SYNC’s or non-periodic
SYNC’s separated by at least three output words,
1SYNC will occur on the second output sample after SYNC.
ORCAL - When high, indicates a potential calibration start.
ORCALD indicates that calibration of the offset
register is complete and the offset sample is avail-
Reserved - Always read low.
USEOR - When high, indicates the Offset Register is
used. During calibration, this bit will read zero indicating the offset register is not being used during calibration.
CSEL- When high, TDATA is selected as the filter
source. When low, the MDATA output signal from
the CS5321 is selected as the input source to the filter.
DECC, DECB, and DECA - Indicate the decimation
rate of the filter and are defined in Table 4.
DECC
DECB
DECA
Output Word Rate (Hz)
Clocks Filter Output
0
0
0
62.5
16384
0
0
1
125
8192
0
1
0
250
4096
0
1
1
500
2048
1
0
0
1000
1024
1
0
1
2000
512
1
1
0
4000
256
1
1
1
Reserved
-
Table 4. Bandwidth Selection: Truth Table
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CS5321/22
2.18 Board Layout Considerations
All of the 0.1 µF filter capacitors on the power supplies, AIN+, and AINR, should be placed very
close to the chip and connect to the nearest ground
pin on the device. The capacitors between VREF+
and VREF- should be located as close to the chip as
possible. The 0.l µF capacitors on the AIN+ and
28
AINR pins should be placed with their leads on the
same axis, not side-by-side. If these capacitors are
placed side-by-side their electric fields can interact
and cause increased distortion. The chip should be
surrounded with a ground plane. Trace fill should
be used around the analog input components.
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CS5321/22
3. CS5321 PIN DESCRIPTIONS
Power Supplies
Vdd1 – Positive Power One, PIN 2
Positive supply voltage. Nominally +5 Volts.
Vdd2 – Positive Power Two, PIN 22
Positive supply voltage. Nominally +5 Volts.
Vss1 – Negative Power One, PIN 3
Negative supply voltage. Nominally -5 Volts.
Vss2 – Negative Power Two, PIN 21
Negative supply voltage. Nominally -5 Volts.
GND1 through GND11 – Ground, PINS 1, 4, 7, 11, 12, 13, 14, 15, 16, 19, 23.
Ground reference.
Analog Inputs
AIN+ - Positive Analog Input, PIN 9
Nominally ± 4.5V
AIN- - Negative Analog Input, PIN 8
This pin is tied to ground.
DS454F3
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CS5321/22
AINR - Analog Input Rough, PIN 10
Allows a non-linear current to bypass the main external anti-aliasing filter which if allowed to
happen, would cause harmonic distortion in the modulator. Please refer to the System
Connection Diagram and the Analog Input and Voltage Reference section of the data sheet for
recommended use of this pin.
VREF+ – Positive Voltage Reference Input, PIN 5
This pin accepts an external +4.5 V voltage reference.
VREF- – Negative Voltage Reference Input, PIN 6
This pin is tied to ground.
Digital Inputs
MCLK – Clock Input, PIN 20
A CMOS-compatible clock input to this pin (nominally 1.024 MHz) provides the necessary
clock for operation of the modulator and data output portions of the A/D converter. MCLK is
normally supplied by the CS5322
MSYNC – Modulator Sync, PIN 25
A transition from a low to high level on this input will re-initialize the CS5321. MSYNC resets
a divider-counter to align the MDATA output bit stream from the CS5321 with the timing
inside the CS5322.
OFST - Offset, PIN 28
When high, adds approximately 100 mV of input referred offset to guarantee that any zero
input limit cycles are out of band if present. When low, zero offset is added.
LPWR - Low Power Mode, PIN 27
The CS5321 power dissipation can be reduced from its nominal value of 55 mW to 30 mW
under the following conditions:
LPWR=1; MCLK = 512 kHz, HBR=1; or LPWR=1; MCLK = 1.024 MHz, HBR=0
HBR – High Bit Rate, Pin 26
Selects either 1 ⁄4 MCLK (HBR=1) or 1 ⁄8MCLK (HBR=0) for the modulator sampling clock.
Digital Outputs
MDATA – Modulator Data Output, PIN 18
Data will be presented in a one-bit serial data stream at a bit rate of 256 kHz (HBR=1) or
128 kHz (HBR=0) with MCLK operating at 1.024 MHz.
MDATA – Modulator Data Output, PIN 17
Inverse of the MDATA output.
MFLG – Modulator Flag, PIN 24
A transition from a low to high level signals that the CS5321 modulator is unstable due to an
overrange on the analog input
30
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CS5321/22
4. CS5322 PIN DESCRIPTIONS
CHIP SELECT
CS
FRAME SYNC
SYNC
R/W
READ/WRITE
CLOCK INPUT CLKIN
RSEL
REGISTER SELECT
RESET RESET
SCLK
SERIAL CLOCK
SID
SERIAL INPUT DATA
SOD
SERIAL OUTPUT DATA
MODULATOR SYNC MSYNC
MODULATOR FLAG
MODULATOR CLOCK
MFLG
MCLK
POSITIVE DIGITAL POWER
VD+
DIGITAL GROUND
DGND
MODULATOR DATA MDATA
TEST DATA TDATA
5
6
7
8
9
4
3
2
1
28 27 2 6 25
CS5322
TOP
VIEW
24
23
22
21
20
10
11
19
12 13 14 15 16 17 18
ERROR ERROR FLAG
DRDY
DATA READY
VD+
POSITIVE DIGITAL POWER
DGND
DIGITAL GROUND
ORCAL OFFSET CALIBRATION
CHANNEL SELECT
CSEL
DECA
DECIMATION RATE CONTROL
HARDWARE/SOFTWARE MODE
H/S
DECB
DECIMATION RATE CONTROL
POWER DOWN PWDN
DECC
DECIMATION RATE CONTROL
USEOR USE OFFSET REGISTER
Power Supplies
VD+ – Positive Digital Power, Pin 8, 21
Positive digital supply voltage. Nominally +5 volts.
DGND – Digital Ground, Pin 9, 20
Digital ground reference.
Digital Outputs
MCLK – Modulator Clock Output, Pin 7
A CMOS-compatible clock output (nominally 1.024 MHz) that provides the necessary clock for
operation of the modulator.
MSYNC – Modulator Sync, Pin 5
The transition from a low to high level on this output will re-initialize the CS5321.
ERROR - Error Flag, Pin 23
This signal is the output of an open pull-up NOR gate with a nominal 100 kΩ pull-up resistor
to which the error status data (OVERWRITE error, MFLG error, ACC1 error and ACC2 error)
are inputs. When low, it notifies the host processor that an error condition exists. The ERROR
signal can be wire OR’d together with other filters’ outputs. The value of the internal pull-up
resistor is 100 kΩ.
DRDY - Data Ready, Pin 22
When high, data is ready to be shifted out of the serial port data register.
DS454F3
31
CS5321/22
SOD - Serial Output Data, Pin 24
The output coding is 2’s complement with the data bits presented MSB first, LSB last. Data
changes on the rising edge of SCLK. An internal nominal 100 kΩ pull-up resistor is included.
Digital Inputs
MDATA – Modulator Data, Pin 10
Data will be presented in a one-bit serial data stream at a bit rate of 256 kHz; (CLKIN =
1.024 MHz).
TDATA - Test Data, Pin 11
Input for user test data.
MFLG – Modulator Flag, Pin 6
A transition from a low to high level signals that the CS5321 modulator is unstable due to an
over-range on the analog input. A Status Bit will be set in the digital filter indicating an error
condition. An internal nominal 100 kΩ pull-down resistor included on the input pin.
RESET - Filter Reset, Pin 4
Performs a hard reset on the chip, all registers and accumulators are cleared. All signals to the
device are locked out except CLKIN. The error flags in the Status Register are set to zero and
the Data Register and Offset Register are set to zero. The configuration register is set to the
values of the corresponding input pins. SYNC must be applied to resume convolutions after
RESET deasserts.
CLKIN - Clock Input, Pin 3
A CMOS-Compatible clock input to this pin (nominally 1.024 MHz) provides the necessary
clock for operation the modulator and filter.
SYNC - Frame Sync, Pin 2
Conversion synchronization input. This signal synchronizes the start of the filter convolution.
More than one SYNC signal can occur with no effect on filter performance, providing the
SYNC signals are perfectly timed at intervals equal to the output sample period.
CSEL - Channel Select, Pin 12
When high, information on the TDATA pin is presented to the digital filter. A low causes data
on the MDATA input to be presented to the digital filter.
PWDN - Powerdown, Pin 14
Powers down the filter when taken high. Convolution cycles in the digital filter and the MCLK
signal are stopped. The registers maintain their data and the serial port remains active. SYNC
must be applied to resume convolutions after PWDN deasserts.
DECA - Decimation Rate Control, Pin 18
See Table 4.
DECB - Decimation Rate Control, Pin 17
See Table 4.
32
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CS5321/22
DECC - Decimation Rate Control, Pin 16
See Table 4.
H/S - Hardware/Software Mode Select, Pin 13
When high, the device pins control device operation; when low, the value entered by a prior
configuration write controls device operation.
CS - Chip Select, Pin 1
When high, all signal activity on the SID, R/W and SCLK pins is ignored. The DRDY and
ERROR signals indicate the status of the chip’s internal operation.
R/W - Read/Write, Pin 28
Used in conjunction with CS such that when both signals are low, the filter inputs data from the
SID pin on the falling edge of SCLK. If CS is low and R/W is high, the filter outputs data on
the SOD pin on the rising edge of SCLK. R/W low floats the SOD pin allowing SID and SOD
to be tied together, forming a bidirectional serial data bus.
SCLK - Serial Clock, Pin 26
Clock signal generated by host processor to either input data on the SID input pin, or output
data on the SOD output pin. For write, data must be valid on the SID pin on the falling edge of
SCLK. Data changes on the SOD pin on the rising edge of SCLK.
SID - Serial Data Input, Pin 25
Data bits are presented MSB first, LSB last. Data is latched on the falling edge of SCLK.
RSEL - Register Select, Pin 27
Selects conversion data when high, or status data when low.
USEOR - Use Offset Register, Pin 15
Use offset register value to correct output words when high. Output words will not be offset
corrected when low.
ORCAL - Offset Register Calibrate, Pin 19
Initiates an offset calibration cycle when SYNC goes high after ORCAL has been toggled from
low to high. The offset value is output on the 57th word following SYNC. Subsequent words
will have their offset correction controlled by USEOR.
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33
CS5321/22
5. PARAMETER DEFINITIONS
Dynamic Range
The ratio of the full-scale (rms) signal to the broadband (rms) noise signal. Broadband noise is
measured with the input grounded within the bandwidth of 1 Hz to f3 Hz (See “CS5322
FILTER CHARACTERISTICS” on page 8). Units in dB.
Signal-to-Distortion
The ratio of the full-scale (rms) signal to the rms sum of all harmonics up to f3 Hz.
Units in dB.
Intermodulation Distortion
The ratio of the rms sum of the two test frequencies (30 and 50 Hz) which are each 6 dB down
from full-scale to the rms sum of all intermodulation components within the bandwidth of dc to
f3 Hz. Units in dB.
Full Scale Error
The ratio of the difference between the value of the voltage reference and analog input voltage
to the full scale span (two times the voltage reference value). This ratio is calculated after the
effects of offset and the external bias components are removed and the analog input voltage is
adjusted. Measurement of this parameter uses the circuitry illustrated in the System Connection
Diagram. Units in %.
Full Scale Drift
The change in the Full Scale value with temperature. Units in %/°C.
Offset
The difference between the analog ground and the analog voltage necessary to yield an output
code from the CS5321/22 of 000000(H). Measurement of this parameter uses the circuit
configuration illustrated in the System Connection Diagram. Units in mV.
Offset Drift
The change in the Offset value with temperature. Measurement of this parameter uses the
circuit configuration illustrated in the System Connection Diagram. Units in µV/°C.
34
DS454F3
CS5321/22
6. PACKAGE DIMENSIONS
28L PLCC PACKAGE DRAWING
e
D2/E2
E1 E
B
A1
D1
D
A
INCHES
DIM
A
A1
B
D
D1
D2
E
E1
E2
e
MIN
0.165
0.090
0.013
0.485
0.450
0.390
0.485
0.450
0.390
0.040
MAX
0.180
0.120
0.021
0.495
0.456
0.430
0.495
0.456
0.430
0.060
MILLIMETERS
MIN
MAX
4.043
4.572
2.205
3.048
0.319
0.533
11.883
12.573
11.025
11.582
9.555
10.922
11.883
12.573
11.025
11.582
9.555
10.922
0.980
1.524
JEDEC #: MS-018
DS454F3
35
CS5321/22
7. ORDERING INFORMATION
Model
Temperature
CS5321-BL
Package
-55 to +85 °C
CS5321-BLZ (Lead Free)
28-pin PLCC
CS5322-BL
-40 to +85 °C
CS5322-BLZ (Lead Free)
8. ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION
Model Number
Peak Reflow Temp
CS5321-BL
225 °C
CS5321-BLZ (Lead Free)
260 °C
CS5322-BL
225 °C
CS5322-BLZ (Lead Free)
260 °C
MSL Rating*
Max Floor Life
2
365 Days
* MSL (Moisture Sensitivity Level) as specified by IPC/JEDEC J-STD-020.
9. REVISION HISTORY
Revision
Date
PP3
OCT 2003
Initial Release.
Changes
F1
AUG 2005
Update ordering information. MSL data added. Change CS5321 TA spec to -40 to +85 degrees.
F2
SEP 2005
Change CS5321 TA spec to -55 to +85 degrees.
F3
NOV 2006
Corrected Ordering Information from 28-SSOP to 28-PLCC.
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
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DS454F3