TI1 ADCS7478AIMFX/NOPB 8-bit a/d converter Datasheet

Sample &
Buy
Product
Folder
Technical
Documents
Support &
Community
Tools &
Software
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
ADCS747x 1-MSPS, 12-Bit, 10-Bit, and 8-Bit A/D Converters
1 Features
3 Description
•
•
•
•
•
The ADCS7476, ADCS7477, and ADCS7478 devices
are low power, monolithic CMOS 12-, 10-, and 8-bit
analog-to-digital converters that operate at 1 MSPS.
The ADCS747x devices are a drop-in replacement for
Analog Device's AD747x. Each device is based on a
successive approximation register architecture with
internal track-and-hold. The serial interface is
compatible with several standards, such as SPI,
QSPI, MICROWIRE, and many common DSP serial
interfaces.
1
•
Variable Power Management
Packaged in 6-Pin SOT-23
Power Supply Used as Reference
Single 2.7-V to 5.25-V Supply Operation
Compatible With SPI™, QSPI™, MICROWIRE™,
and DSP
Key Specifications
– Resolution With No Missing Codes (12-Bit, 10Bit, and 8-Bit)
– Conversion Rate: 1 MSPS
– DNL: 0.5, –0.3 LSB (Typical)
– INL: ±0.4 LSB (Typical)
– Power Consumption:
– 3-V Supply: 2 mW (Typical)
– 5-V Supply: 10 mW (Typical)
2 Applications
•
•
•
•
•
•
Automotive Navigation
FA or ATM Equipment
Portable Systems
Medical Instruments
Mobile Communications
Instrumentation and Control Systems
The ADCS747x uses the supply voltage as a
reference, enabling the device to operate with a fullscale input range of 0 to VDD. The conversion rate is
determined from the serial clock (SCLK) speed.
These converters offer a shutdown mode, which can
be used to trade throughput for power consumption.
The ADCS747x is operated with a single supply that
can range from 2.7 V to 5.25 V. Normal power
consumption during continuous conversion, using a
3-V or 5-V supply, is 2 mW or 10 mW respectively.
The power-down feature, which is enabled by a chip
select (CS) pin, reduces the power consumption to
under 5 µW using a 5-V supply. All three converters
are available in a 6-pin SOT-23 package, which
provides an extremely small footprint for applications
where space is a critical consideration. These
products are designed for operation over the
automotive and extended industrial temperature
range of −40°C to 125°C.
Device Information(1)
PART NUMBER
ADCS7476
ADCS7477
ADCS7478
PACKAGE
SOT-23 (6)
BODY SIZE (NOM)
1.60 mm × 2.90 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Block Diagram
VIN
ADCS7476
ADCS7477
ACDS7478
T/H
SUCCESSIVE
APPROXIMATION
ADC
SCLK
CONTROL
LOGIC
CS
SDATA
Copyright © 2016, Texas Instruments Incorporated
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
7
1
1
1
2
3
4
Absolute Maximum Ratings ...................................... 4
ESD Ratings.............................................................. 4
Recommended Operating Conditions....................... 4
Thermal Information ................................................. 4
Electrical Characteristics – ADCS7476..................... 5
Electrical Characteristics – ADCS7477..................... 6
Electrical Characteristics – ADCS7478..................... 8
Timing Requirements ................................................ 9
Typical Characteristics ............................................ 12
Detailed Description ............................................ 16
7.1 Overview ................................................................. 16
7.2 Functional Block Diagram ....................................... 16
7.3 Feature Description................................................. 16
7.4 Device Functional Modes........................................ 17
8
Application and Implementation ........................ 21
8.1 Application Information............................................ 21
8.2 Typical Application .................................................. 22
9
Power Supply Recommendations...................... 23
9.1 Power Supply Noise............................................... 23
9.2 Digital Output Effect Upon Noise ........................... 23
9.3 Power Management ................................................ 23
10 Layout................................................................... 24
10.1 Layout Guidelines ................................................. 24
10.2 Layout Example ................................................... 25
11 Device and Documentation Support ................. 26
11.1
11.2
11.3
11.4
11.5
Device Support......................................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
26
27
27
27
27
12 Mechanical, Packaging, and Orderable
Information ........................................................... 27
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision F (March 2013) to Revision G
Page
•
Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section .................................................................................................. 1
•
Moved VDD from the Electrical Characteristics tables to the Recommended Operating Conditions table ............................. 5
Changes from Revision E (March 2013) to Revision F
•
2
Page
Changed layout of National Data Sheet to TI format ............................................................................................................. 1
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
5 Pin Configuration and Functions
DBV Package
6-Pin SOT-23
Top View
VDD
1
6
CS
GND
2
5
SDATA
VIN
3
4
SCLK
Not to scale
Pin Functions
PIN
NO.
NAME
TYPE (1)
DESCRIPTION
1
VDD
P
Positive supply pin. These pins must be connected to a quiet 2.7-V to 5.25-V source and bypassed
to GND with 0.1-µF and 1-µF monolithic capacitors placed within 1 cm of the power pin. ADCS747x
uses this power supply as a reference, so it must be thoroughly bypassed.
2
GND
G
The ground return for the supply.
3
VIN
I
Analog input. This signal can range from 0 V to VDD.
4
SCLK
I
Digital clock input. The range of frequencies for this input is 10 kHz to 20 MHz, with ensured
performance at 20 MHz. This clock directly controls the conversion and readout processes.
5
SDATA
O
Digital data output. The output words are clocked out of this pin by the SCLK pin.
6
CS
I
Chip select. A conversion process begins on the falling edge of CS.
(1)
G = Ground, I = Input, O = Output, P = Power
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
3
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1) (2)
MIN
MAX
UNIT
Supply voltage, VDD
–0.3
6.5
V
Voltage on any analog pin to GND
–0.3
VDD + 0.3
V
Voltage on any digital pin to GND
–0.3
6.5
V
Input current at any pin (except power supply pins)
±10
mA
Soldering temperature, infrared (10 sec)
215
°C
Operating temperature, TA
150
°C
150
°C
Storage temperature, Tstg
(1)
(2)
–65
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
(1)
UNIT
±3500
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
V
±200
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
VDD
MIN
MAX
UNIT
2.7
5.25
V
Digital input pins voltage (independent of supply voltage)
2.7
5.25
V
Operating temperature
–40
125
°C
Supply voltage
TA
6.4 Thermal Information
ADCS7476,
ADCS7477,
ADCS7478
THERMAL METRIC (1)
UNIT
DBV (SOT-23)
6 PINS
RθJA
Junction-to-ambient thermal resistance
184.5
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
151.2
°C/W
RθJB
Junction-to-board thermal resistance
29.7
°C/W
ψJT
Junction-to-top characterization parameter
29.8
°C/W
ψJB
Junction-to-board characterization parameter
29.1
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
6.5 Electrical Characteristics – ADCS7476
TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted) (1)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
STATIC CONVERTER CHARACTERISTICS
Resolution with no missing codes
INL
Integral non-linearity
VDD = 2.7 V to 3.6 V, –40°C ≤ TA ≤ 125°C
VDD = 2.7 V to 3.6 V
12
TA = 25°C
±0.4
–40°C ≤ TA ≤ 85°C
±1
VDD = 2.7 V to 3.6 V, TA = 125°C
DNL
Differential non-linearity
VDD = 2.7 V to 3.6 V
–1.1
TA = 25°C
–0.3
–40°C ≤ TA ≤ 85°C
–0.9
1
0.5
1
VDD = 2.7 V to 3.6 V, TA = 125°C
VOFF
Offset error
VDD = 2.7 V to 3.6 V
GE
Gain error
VDD = 2.7 V to 3.6 V
±1
TA = 25°C
±0.1
−40°C ≤ TA ≤ 125°C
±1.2
TA = 25°C
±0.2
–40°C ≤ TA ≤ 125°C
±1.2
Bits
LSB
LSB
LSB
LSB
LSB
LSB
DYNAMIC CONVERTER CHARACTERISTICS
TA = 25°C
72
SINAD
Signal-to-noise plus distortion ratio fIN = 100 kHz
SNR
Signal-to-noise ratio
THD
Total harmonic distortion
fIN = 100 kHz
–80
dB
SFDR
Spurious-free dynamic range
fIN = 100 kHz
82
dB
Intermodulation distortion,
second order terms
fa = 103.5 kHz, fb = 113.5 kHz
–78
dB
Intermodulation distortion,
third order terms
fa = 103.5 kHz, fb = 113.5 kHz
–78
dB
5-V supply
11
MHz
3-V supply
8
MHz
VDD = 4.75 V to 5.25 V, SCLK On or Off
2
mA
VDD = 2.7 V to 3.6 V, SCLK On or Off
1
mA
VDD = 4.75 V to 5.25 V,
fSAMPLE = 1 MSPS
TA = 25°C
2
VDD = 2.7 V to 3.6 V,
fSAMPLE = 1 MSPS
TA = 25°C
fIN = 100 kHz
–40°C ≤ TA ≤ 125°C
TA = 25°C
72.5
–40°C ≤ TA ≤ 85°C
FPBW
–3-dB full power bandwidth
dB
70.8
fIN = 100 kHz, TA = 125°C
IMD
dB
70
70.6
dB
POWER SUPPLY CHARACTERISTICS
Normal mode (static)
IDD
Normal mode (operational)
Shutdown mode
Power consumption,
normal mode (operational)
PD
Power consumption,
shutdown mode
–40°C ≤ TA ≤ 85°C
3.5
0.6
–40°C ≤ TA ≤ 85°C
1.6
VDD = 5 V, SCLK Off
VDD = 5 V, SCLK On
VDD = 5 V,
fSAMPLE = 1 MSPS
TA = 25°C
VDD = 3 V,
fSAMPLE = 1 MSPS
TA = 25°C
mA
mA
0.5
µA
60
µA
10
–40°C ≤ TA ≤ 85°C
17.5
2
–40°C ≤ TA ≤ 85°C
4.8
mW
mW
VDD = 5 V, SCLK Off
2.5
µW
VDD = 3 V, SCLK Off
1.5
µW
ANALOG INPUT CHARACTERISTICS
VIN
Input range
IDCL
DC leakage current
CINA
Analog input capacitance
0 to VDD
–40°C ≤ TA ≤ 85°C
V
±1
30
µA
pF
DIGITAL INPUT CHARACTERISTICS
(1)
Data sheet minimum and maximum specification limits are ensured by design, test, or statistical analysis.
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
5
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
Electrical Characteristics – ADCS7476 (continued)
TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted)(1)
PARAMETER
VIH
TEST CONDITIONS
–40°C ≤ TA ≤ 85°C
Input high voltage
VIL
Input low voltage
IIN
Input current
CIND
Digital input capacitance
MIN
TYP
MAX
2.4
UNIT
V
VDD = 5 V, –40°C ≤ TA ≤ 85°C
0.8
V
VDD = 3 V, –40°C ≤ TA ≤ 85°C
0.4
V
±1
µA
VIN = 0 V or VDD
TA = 25°C
±10
nA
–40°C ≤ TA ≤ 85°C
TA = 25°C
2
–40°C ≤ TA ≤ 85°C
4
pF
DIGITAL OUTPUT CHARACTERISTICS
VOH
Output high voltage
ISOURCE = 200 µA, VDD = 2.7 V to 5.25 V,
–40°C ≤ TA ≤ 85°C
VOL
Output low voltage
ISINK = 200 µA, –40°C ≤ TA ≤ 85°C
0.4
V
IOL
TRI-STATE leakage current
–40°C ≤ TA ≤ 85°C
±10
µA
COUT
TRI-STATE output capacitance
VDD – 0.2
TA = 25°C
V
2
–40°C ≤ TA ≤ 85°C
4
Output coding
pF
Straight (natural) binary
AC ELECTRICAL CHARACTERISTICS
fSCLK
Clock frequency
–40°C ≤ TA ≤ 125°C
DC
SCLK duty cycle
–40°C ≤ TA ≤ 85°C
tTH
Track or hold acquisition time
–40°C ≤ TA ≤ 85°C
400
fRATE
Throughput rate
–40°C ≤ TA ≤ 85°C
1
tAD
Aperture delay
3
ns
tAJ
Aperture jitter
30
ps
20
40%
MHz
60%
ns
MSPS
6.6 Electrical Characteristics – ADCS7477
TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted) (1)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
STATIC CONVERTER CHARACTERISTICS
Resolution with no missing codes
INL
Integral non-linearity
DNL
Differential non-linearity
VOFF
Offset error
GE
Gain error
–40°C ≤ TA ≤ 85°C
10
TA = 25°C
±0.2
–40°C ≤ TA ≤ 85°C
±0.7
TA = 25°C
–0.2
0.3
T–40°C ≤ TA ≤ 85°C
±0.7
±0.7
TA = 25°C
±0.1
–40°C ≤ TA ≤ 85°C
±0.7
TA = 25°C
±0.2
–40°C ≤ TA ≤ 85°C
±1
Bits
LSB
LSB
LSB
LSB
DYNAMIC CONVERTER CHARACTERISTICS
SINAD
Signal-to-noise plus distortion ratio fIN = 100 kHz
SNR
Signal-to-noise ratio
Total harmonic distortion
fIN = 100 kHz
SFDR
Spurious-free dynamic range
fIN = 100 kHz
6
61.7
–40°C ≤ TA ≤ 85°C
dBFS
61
fIN = 100 kHz
THD
(1)
TA = 25°C
62
TA = 25°C
dB
–77
–40°C ≤ TA ≤ 85°C
–73
TA = 25°C
78
–40°C ≤ TA ≤ 85°C
74
dB
dB
Data sheet minimum and maximum specification limits are ensured by design, test, or statistical analysis.
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
Electrical Characteristics – ADCS7477 (continued)
TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted)(1)
PARAMETER
IMD
FPBW
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Intermodulation distortion,
second order terms
fa = 103.5 kHz, fb = 113.5 kHz
–78
dB
Intermodulation distortion,
third order terms
fa = 103.5 kHz, fb = 113.5 kHz
–78
dB
5-V supply
11
MHz
3-V supply
8
MHz
VDD = 4.75 V to 5.25 V, SCLK On or Off
2
mA
VDD = 2.7 V to 3.6 V, SCLK On or Off
1
mA
VDD = 4.75 V to 5.25 V,
fSAMPLE = 1 MSPS
TA = 25°C
2
VDD = 2.7 V to 3.6 V,
fSAMPLE = 1 MSPS
TA = 25°C
–3-dB full power bandwidth
POWER SUPPLY CHARACTERISTICS
Normal mode (static)
IDD
Normal mode (operational)
Shutdown mode
Power consumption,
normal mode (operational)
PD
Power consumption,
shutdown mode
–40°C ≤ TA ≤ 85°C
0.6
–40°C ≤ TA ≤ 85°C
0.5
VDD = 5 V, SCLK On
60
TA = 25°C
VDD = 3 V,
fSAMPLE = 1 MSPS
TA = 25°C
mA
1.6
VDD = 5 V, SCLK Off
VDD = 5 V,
fSAMPLE = 1 MSPS
mA
3.5
µA
10
–40°C ≤ TA ≤ 85°C
mW
17.5
2
–40°C ≤ TA ≤ 85°C
mW
4.8
VDD = 5 V, SCLK Off
2.5
VDD = 3 V, SCLK Off
1.5
µW
ANALOG INPUT CHARACTERISTICS
VIN
Input range
IDCL
DC leakage current
CINA
Analog input capacitance
0 to VDD
TA = −40°C to 85°C
V
±1
µA
30
pF
DIGITAL INPUT CHARACTERISTICS
VIH
Input high voltage
VIL
Input low voltage
IIN
CIND
TA = −40°C to 85°C
Input current
2.4
VDD = 5 V, –40°C ≤ TA ≤ 85°C
0.8
VDD = 3 V, –40°C ≤ TA ≤ 85°C
0.4
VIN = 0 V or VDD
TA = 25°C
V
V
±10
–40°C ≤ TA ≤ 85°C
nA
±1
TA = 25°C
Digital input capacitance
V
µA
2
–40°C ≤ TA ≤ 85°C
pF
4
DIGITAL OUTPUT CHARACTERISTICS
VOH
Output high voltage
ISOURCE = 200 µA, VDD = 2.7 V to 5.25 V,
–40°C ≤ TA ≤ 85°C
VOL
Output low voltage
ISINK = 200 µA, –40°C ≤ TA ≤ 85°C
IOL
TRI-STATE leakage current
–40°C ≤ TA ≤ 85°C
COUT
TRI-STATE output capacitance
VDD – 0.2
TA = 25°C
V
0.4
V
±10
µA
2
–40°C ≤ TA ≤ 85°C
pF
4
Output coding
Straight (natural) binary
AC ELECTRICAL CHARACTERISTICS
fSCLK
Clock frequency
–40°C ≤ TA ≤ 85°C
DC
SCLK duty cycle
–40°C ≤ TA ≤ 85°C
tTH
Track or hold acquisition time
–40°C ≤ TA ≤ 85°C
400
fRATE
Throughput rate
–40°C ≤ TA ≤ 85°C
1
tAD
Aperture delay
20
40%
MHz
60%
ns
MSPS
3
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ns
7
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
Electrical Characteristics – ADCS7477 (continued)
TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted)(1)
PARAMETER
tAJ
TEST CONDITIONS
MIN
Aperture jitter
TYP
MAX
30
UNIT
ps
6.7 Electrical Characteristics – ADCS7478
TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted) (1)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
STATIC CONVERTER CHARACTERISTICS
Resolution with no missing codes
INL
Integral non-linearity
DNL
Differential non-linearity
VOFF
Offset error
GE
Gain error
–40°C ≤ TA ≤ 85°C
8
TA = 25°C
±0.05
–40°C ≤ TA ≤ 85°C
±0.3
TA = 25°C
±0.07
–40°C ≤ TA ≤ 85°C
±0.3
TA = 25°C
±0.03
–40°C ≤ TA ≤ 85°C
±0.3
TA = 25°C
±0.08
–40°C ≤ TA ≤ 85°C
±0.4
TA = 25°C
Total unadjusted error
±0.07
–40°C ≤ TA ≤ 85°C
±0.3
Bits
LSB
LSB
LSB
LSB
LSB
DYNAMIC CONVERTER CHARACTERISTICS
SINAD
Signal-to-noise plus distortion ratio fIN = 100 kHz
SNR
Signal-to-noise ratio
TA = 25°C
49.7
–40°C ≤ TA ≤ 85°C
dB
49
fIN = 100 kHz
49.7
TA = 25°C
dB
–77
THD
Total harmonic distortion
fIN = 100 kHz
SFDR
Spurious-free dynamic range
fIN = 100 kHz
Intermodulation distortion,
second order terms
fa = 103.5 kHz, fb = 113.5 kHz
–68
dB
Intermodulation distortion,
third order terms
fa = 103.5 kHz, fb = 113.5 kHz
–68
dB
5-V supply
11
MHz
3-V supply
8
MHz
VDD = 4.75 V to 5.25 V, SCLK On or Off
2
mA
VDD = 2.7 V to 3.6 V, SCLK On or Off
1
mA
VDD = 4.75 V to 5.25 V,
fSAMPLE = 1 MSPS
TA = 25°C
2
VDD = 2.7 V to 3.6 V,
fSAMPLE = 1 MSPS
TA = 25°C
IMD
FPBW
–3-dB full power bandwidth
–40°C ≤ TA ≤ 85°C
–65
TA = 25°C
69
–40°C ≤ TA ≤ 85°C
dB
dB
65
POWER SUPPLY CHARACTERISTICS
Normal mode (static)
IDD
Normal mode (operational)
Shutdown mode
(1)
8
–40°C ≤ TA ≤ 85°C
3.5
0.6
–40°C ≤ TA ≤ 85°C
1.6
VDD = 5 V, SCLK Off
0.5
VDD = 5 V, SCLK On
60
mA
mA
µA
Data sheet min/max specification limits are ensured by design, test, or statistical analysis.
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
Electrical Characteristics – ADCS7478 (continued)
TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted)(1)
PARAMETER
TEST CONDITIONS
Power consumption,
normal mode (operational)
PD
Power consumption,
shutdown mode
VDD = 5 V,
fSAMPLE = 1 MSPS
TA = 25°C
VDD = 3 V,
fSAMPLE = 1 MSPS
TA = 25°C
MIN
TYP
MAX
UNIT
10
–40°C ≤ TA ≤ 85°C
mW
17.5
2
–40°C ≤ TA ≤ 85°C
mW
4.8
VDD = 5 V, SCLK Off
2.5
VDD = 3 V, SCLK Off
1.5
µW
ANALOG INPUT CHARACTERISTICS
VIN
Input range
IDCL
DC leakage current
0 to VDD
CINA
Analog input capacitance
V
–40°C ≤ TA ≤ 85°C
±1
µA
30
pF
DIGITAL INPUT CHARACTERISTICS
VIH
–40°C ≤ TA ≤ 85°C
Input high voltage
VIL
Input low voltage
IIN
V
0.8
VDD = 3 V, –40°C ≤ TA ≤ 85°C
Digital input current
CIND
2.4
VDD = 5 V, –40°C ≤ TA ≤ 85°C
0.4
TA = 25°C
VIN = 0 V or VDD
V
±10
nA
–40°C ≤ TA ≤ 85°C
±1
TA = 25°C
Input capacitance
V
µA
2
–40°C ≤ TA ≤ 85°C
p
4
DIGITAL OUTPUT CHARACTERISTICS
VOH
Output high voltage
ISOURCE = 200 µA, VDD = 2.7 V to 5.25 V,
–40°C ≤ TA ≤ 85°C
VOL
Output low voltage
ISINK = 200 µA, –40°C ≤ TA ≤ 85°C
0.4
V
IOL
TRI-STATE leakage current
–40°C ≤ TA ≤ 85°C
±10
µA
COUT
TRI-STATE output capacitance
4
pF
20
MHz
VDD − 0.2
V
2
Output coding
Straight (natural) binary
AC ELECTRICAL CHARACTERISTICS
fSCLK
Clock frequency
–40°C ≤ TA ≤ 85°C
DC
SCLK duty cycle
–40°C ≤ TA ≤ 85°C
tTH
Track or hold acquisition time
–40°C ≤ TA ≤ 85°C
fRATE
Throughput rate
–40°C ≤ TA ≤ 85°C (see Application Information)
tAD
Aperture delay
3
ns
tAJ
Aperture jitter
30
ps
40%
60%
400
1
ns
MSPS
6.8 Timing Requirements
–40°C ≤ TA ≤ 85°C, VDD = 2.7 V to 5.25 V, and fSCLK = 20 MHz (unless otherwise noted) (1)
PARAMETER
CONDITIONS
tCONVERT
MIN
TA = 25°C
TYP
MAX
UNIT
16 × tSCLK
tQUIET
Quiet time (2)
50
ns
t1
Minimum CS pulse width
10
ns
t2
CS to SCLK setup time
10
ns
t3
Delay from CS until SDATA TRI-STATE
disabled (3)
(1)
(2)
(3)
20
ns
All input signals are specified as tr = tf = 5 ns (10% to 90% VDD) and timed from 1.6 V.
Minimum quiet time required between bus relinquish and start of next conversion.
Measured with the load circuit (Figure 1), and defined as the time taken by the output to cross 1 V.
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
9
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
Timing Requirements (continued)
–40°C ≤ TA ≤ 85°C, VDD = 2.7 V to 5.25 V, and fSCLK = 20 MHz (unless otherwise noted)(1)
PARAMETER
CONDITIONS
t4
Data access time after SCLK falling edge (4)
t5
SCLK low pulse width
t6
SCLK high pulse width
t7
SCLK to data valid hold time
TYP
MAX
UNIT
VDD = 2.7 V to 3.6 V
40
ns
VDD = 4.75 V to 5.25 V
20
ns
0.4 × tSCLK
ns
0.4 × tSCLK
ns
VDD = 2.7 V to 3.6 V
7
ns
VDD = 4.75 V to 5.25 V
5
6
VDD = 4.75 V to 5.25 V
5
t8
SCLK falling edge to SDATA high
impedance (5)
VDD = 2.7 V to 3.6 V
tPOWER-UP
Power-up time from full power down
TA = 25°C
(4)
(5)
MIN
ns
25
25
1
ns
ns
µs
Measured with the load circuit (Figure 1), and defined as the time taken by the output to cross 1 V or 2 V.
t8 is derived from the time taken by the outputs to change by 0.5 V with the loading circuit (Figure 1). The measured number is then
adjusted to remove the effects of charging or discharging the 25-pF capacitor. This means t8 is the true bus relinquish time, independent
of the bus loading.
Figure 1. Timing Test Circuit
Figure 2. ADCS7476 Serial Interface Timing Diagram
10
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
Figure 3. ADCS7477 Serial Interface Timing Diagram
Figure 4. ADCS7478 Serial Interface Timing Diagram
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
11
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
6.9 Typical Characteristics
TA = 25°C, VDD = 3 V, fSAMPLE = 1 MSPS, fSCLK = 20 MHz, and fIN = 100 kHz (unless otherwise noted)
12
Figure 5. ADCS7476 DNL
Figure 6. ADCS7476 INL
Figure 7. ADCS7476 Spectral Response at 100-kHz Input
Figure 8. ADCS7476 THD vs Source Impedance
Figure 9. ADCS7476 THD vs Input Frequency, 600 KSPS
Figure 10. ADCS7476 THD vs Input Frequency, 1 MSPS
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
Typical Characteristics (continued)
TA = 25°C, VDD = 3 V, fSAMPLE = 1 MSPS, fSCLK = 20 MHz, and fIN = 100 kHz (unless otherwise noted)
Figure 11. ADCS7476 SINAD vs Input Frequency, 600 KSPS
Figure 12. ADCS7476 SINAD vs Input Frequency, 1 MSPS
Figure 13. ADCS7476 SNR vs fSCLK
Figure 14. ADCS7476 SINAD vs fSCLK
Figure 15. ADCS7477 DNL
Figure 16. ADCS7477 INL
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
13
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
Typical Characteristics (continued)
TA = 25°C, VDD = 3 V, fSAMPLE = 1 MSPS, fSCLK = 20 MHz, and fIN = 100 kHz (unless otherwise noted)
14
Figure 17. ADCS7477 Spectral Response at 100-kHz Input
Figure 18. ADCS7477 SNR vs fSCLK
Figure 19. ADCS7477 SINAD vs fSCLK
Figure 20. ADCS7478 DNL
Figure 21. ADCS7478 INL
Figure 22. ADCS7478 Spectral Response at 100-kHz Input
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
Typical Characteristics (continued)
TA = 25°C, VDD = 3 V, fSAMPLE = 1 MSPS, fSCLK = 20 MHz, and fIN = 100 kHz (unless otherwise noted)
Figure 23. ADCS7478 SNR vs fSCLK
Copyright © 2003–2016, Texas Instruments Incorporated
Figure 24. ADCS7478 SINAD vs fSCLK
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
15
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
7 Detailed Description
7.1 Overview
The ADCS747x devices are successive-approximation analog-to-digital converters designed around a chargeredistribution digital-to-analog converter. Simplified schematics of the ADCS747x in both track and hold operation
are shown in Figure 25 and Figure 26. In Figure 26, the device is in track mode where the switch SW1 connects
the sampling capacitor to the input, and SW2 balances the comparator inputs. The device is in this state until CS
is brought low, at which point the device moves to hold mode.
7.2 Functional Block Diagram
VIN
ADCS7476
ADCS7477
ACDS7478
T/H
SUCCESSIVE
APPROXIMATION
ADC
SCLK
CONTROL
LOGIC
CS
SDATA
Copyright © 2016, Texas Instruments Incorporated
7.3 Feature Description
Serial interface timing diagrams for the ADCS747x are shown in Figure 2, Figure 3, and Figure 4. CS is chip
select, which initiates conversions and frames the serial data transfers. SCLK (serial clock) controls both the
conversion process and the timing of serial data. SDATA is the serial data out pin, where a conversion result is
found.
Basic operation of the ADCS747x begins with CS going low, which initiates a conversion process and data
transfer. Subsequent rising and falling edges of SCLK will be labeled with reference to the falling edge of CS; for
example, the third falling edge of SCLK shall refer to the third falling edge of SCLK after CS goes low.
At the fall of CS, the SDATA pin comes out of TRI-STATE, and the converter moves from track mode to hold
mode. The input signal is sampled and held for conversion at the falling edge of CS. The converter moves from
hold mode to track mode on the 13th rising edge of SCLK (see Figure 2, Figure 3, or Figure 4). The SDATA pin
is placed back into TRI-STATE after the 16th falling edge of SCLK, or at the rising edge of CS, whichever occurs
first. After a conversion is completed, the quiet time tQUIET must be satisfied before bringing CS low again to
begin another conversion.
Sixteen SCLK cycles are required to read a complete sample from the ADCS747x. The sample bits (including
any leading or trailing zeroes) are clocked out on falling edges of SCLK, and are intended to be clocked in by a
receiver on subsequent falling edges of SCLK. ADCS747x produces four leading zeroes on SDATA, followed by
twelve, ten, or eight data bits (the most significant first). After the data bits, the ADCS7477 clocks out two trailing
zeros, and the ADCS7478 clocks out four trailing zeros. The ADCS7476 does not clock out any trailing zeros; the
least significant data bit is valid on the 16th falling edge of SCLK.
Depending upon the application, the first edge on SCLK after CS goes low may be either a falling edge or a
rising edge. If the first SCLK edge after CS goes low is a rising edge, all four leading zeroes are valid on the first
four falling edges of SCLK. If instead the first SCLK edge after CS goes low is a falling edge, the first leading
zero may not be set up in time for a microprocessor or DSP to read it correctly. The remaining data bits are still
clocked out on the falling edges of SCLK.
16
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
7.4 Device Functional Modes
Figure 25 shows the device in hold mode where the switch SW1 connects the sampling capacitor to ground,
maintaining the sampled voltage, and switch SW2 unbalances the comparator. The control logic then instructs
the charge-redistribution DAC to add or subtract fixed amounts of charge from the sampling capacitor until the
comparator is balanced. When the comparator is balanced, the digital word supplied to the DAC is the digital
representation of the analog input voltage. The device moves from hold mode to track mode (Figure 26) on the
13th rising edge of SCLK.
CHARGE
REDISTRIBUTION
DAC
VIN
SAMPLING
CAPACITOR
SW1
+
-
CONTROL
LOGIC
SW2
GND
VDD/2
Figure 25. ADCS747x in Hold Mode
CHARGE
REDISTRIBUTION
DAC
VIN
SAMPLING
CAPACITOR
SW1
+
SW2
-
CONTROL
LOGIC
GND
VDD/2
Figure 26. ADCS747x in Track Mode
7.4.1 Transfer Function
The output format of ADCS747x is straight binary. Code transitions occur midway between successive integer
LSB values. The LSB widths for the ADCS7476 is VDD / 4096; for the ADCS7477 the LSB width is VDD / 1024; for
the ADCS7478, the LSB width is VDD / 256. The ideal transfer characteristic for the ADCS7476 and ADCS7477 is
shown in Figure 27, while the ideal transfer characteristic for the ADCS7478 is shown in Figure 28.
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
17
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
Device Functional Modes (continued)
Figure 27. ADCS7476/77 Ideal Transfer Characteristic
Figure 28. ADCS7478 Ideal Transfer Characteristic
7.4.2 Power-Up Timing
The ADCS747x typically requires 1 µs to power up, either after first applying VDD, or after returning to normal
mode from shutdown mode. This corresponds to one dummy conversion for any SCLK frequency within the
specifications in this document. After this first dummy conversion, the ADCS747x performs conversions properly.
NOTE
The tQUIET time must still be included between the first dummy conversion and the second
valid conversion.
18
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
Device Functional Modes (continued)
7.4.3 Modes of Operation
The ADCS747x has two possible modes of operation: Normal Mode and Shutdown Mode. ADCS747x enters
normal mode (and a conversion process is begun) when CS is pulled low. The device enters shutdown mode if
CS is pulled high before the tenth falling edge of SCLK after CS is pulled low, or stays in normal mode if CS
remains low. Once in shutdown mode, the device stays there until CS is brought low again. By varying the ratio
of time spent in the normal and shutdown modes, a system may trade off throughput for power consumption.
7.4.3.1 Normal Mode
The best possible throughput is obtained by leaving the ADCS747x in normal mode at all times, so there are no
power-up delays. To keep the device in normal mode continuously, CS must be kept low until after the 10th
falling edge of SCLK after the start of a conversion (remember that a conversion is initiated by bringing CS low).
If CS is brought high after the 10th falling edge, but before the 16th falling edge, the device remains in normal
mode, but the current conversion is aborted, and SDATA returns to TRI-STATE (truncating the output word).
Sixteen SCLK cycles are required to read all of a conversion word from the device. After sixteen SCLK cycles
have elapsed, CS may be idled either high or low until the next conversion. If CS is idled low, it must be brought
high again before the start of the next conversion, which begins when CS is again brought low.
After sixteen SCLK cycles, SDATA returns to TRI-STATE. Another conversion may be started, after tQUIET has
elapsed, by bringing CS low again.
7.4.3.2 Start-Up Mode
When the VDD supply is first applied, the ADCS747x may power up in either of the two modes: normal or
shutdown. As such, one dummy conversion should be performed after start-up, exactly as described in PowerUp Timing. The part may then be placed into either normal mode or the shutdown mode, as described in Normal
Mode and Shutdown Mode.
7.4.3.3 Shutdown Mode
Shutdown mode is appropriate for applications that either do not sample continuously, or are willing to trade
throughput for power consumption. When the ADCS747x is in shutdown mode, all of the analog circuitry is
turned off.
To enter shutdown mode, a conversion must be interrupted by bringing CS back high anytime between the
second and tenth falling edges of SCLK, as shown in Figure 29. Once CS has been brought high in this manner,
the device enters shutdown mode; the current conversion is aborted and SDATA enters TRI-STATE. If CS is
brought high before the second falling edge of SCLK, the device does not change mode; this is to avoid
accidentally changing mode as a result of noise on the CS line.
Figure 29. Entering Shutdown Mode
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
19
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
Device Functional Modes (continued)
Figure 30. Entering Normal Mode
To exit shutdown mode, bring CS back low. Upon bringing CS low, the ADCS747x begins powering up. Power
up typically takes 1 µs. This microsecond of power-up delay results in the first conversion result being unusable.
The second conversion performed after power-up, however, is valid, as shown in Figure 30.
If CS is brought back high before the 10th falling edge of SCLK, the device returns to shutdown mode. This is
done to avoid accidentally entering normal mode as a result of noise on the CS line. To exit shutdown mode and
remain in normal mode, CS must be kept low until after the 10th falling edge of SCLK. The ADCS747x is fully
powered up after 16 SCLK cycles.
20
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
A typical application of ADCS747x is shown in Figure 32. The combined analog and digital supplies are provided
in this example by the TI LP2950 low-dropout voltage regulator, available in a variety of fixed and adjustable
output voltages. The supply is bypassed with a capacitor network located close to the device. The three-wire
interface is also shown connected to a microprocessor or DSP.
8.1.1 Analog Inputs
An equivalent circuit for the ADCS747x input channel is shown in Figure 31. The diodes D1 and D2 provide ESD
protection for the analog inputs. At no time should an analog input exceed VDD + 300 mV or GND – 300 mV, as
these ESD diodes begin conducting current into the substrate or supply line and affect ADC operation.
The capacitor C1 in Figure 31 typically has a value of 4 pF, and is mainly due to pin capacitance. The resistor R1
represents the ON resistance of the multiplexer and track or hold switch, and is typically 100 Ω. The capacitor C2
is the ADCS747x sampling capacitor, and is typically 26 pF.
The sampling nature of the analog input causes input current pulses that result in voltage spikes at the input.
ADCS747x delivers best performance when driven by a low-impedance source to eliminate distortion caused by
the charging of the sampling capacitance. In some applications where dynamic performance is critical, the input
must be driven with a low output-impedance amplifier. In addition, when using ADCS747x to sample AC signals,
a band-pass or low-pass filter reduces harmonics and noise and thus improve THD and SNR.
Figure 31. Equivalent Input Circuit
8.1.2 Digital Inputs and Outputs
The ADCS747x digital inputs (SCLK and CS) are not limited by the same absolute maximum ratings as the
analog inputs. The digital input pins are instead limited to 6.5 V with respect to GND, regardless of VDD, the
supply voltage. This allows ADCS747x to be interfaced with a wide range of logic levels, independent of the
supply voltage.
NOTE
Even though the digital inputs are tolerant of up to 6.5 V above GND, the digital outputs
are only capable of driving VDD out.
In addition, the digital input pins are not prone to latch-up; SCLK and CS may be asserted before VDD without
any risk.
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
21
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
8.2 Typical Application
The ADCS747x are monolithic CMOS 12-, 10-, and 8-bit ADCs that use the supply voltage as a reference,
enabling the devices to operate with a full-scale input range of 0 to VDD. An example low-power application with
the LMT87, which is a wide range ±0.3°C accurate temperature sensor, is shown in Figure 32.
VSUPPLY
LP2950
1 µF
1 µF
0.1 µF
VDD
LMT87
OUT
VDD
CBP
VIN
CS
ADCS747X SCLK
GND
GND
DSP
Microcontroller
SDATA
Copyright © 2016, Texas Instruments Incorporated
Figure 32. Typical Application Circuit
8.2.1 Design Requirements
A successful ADCS747x and LMT87 design is constrained by the following factors:
• VIN range must be 0 V to VDD where VDD can range from 2.7 V to 5.25 V.
8.2.2 Detailed Design Procedure
Designing for an accurate measurement requires careful attention to the timing requirements for the ADCS747x
parts.
Because the ADC747x parts use the supply voltage as a reference, ensuring that the supply voltage is settled to
its final level before exiting the shutdown mode and beginning a conversion is important. After the supply voltage
has settled, the CS is brought to a low level (ideally 0 V) to start a conversion.
Ensuring that any noise on the power supply is less than ½ LSB in amplitude is also important. The supply
voltage must be regarded as a precise voltage reference.
After the CS has been brought low, the user must wait for one complete conversion cycle (approximately 1 μs)
for meaningful data. The dummy conversion cycle is the start-up time of the ADCS747x. The ADCS747x digital
output can then be correlated to the LMT87 output level to get an accurate temperature reading. At VDD = 3.3 V,
1 LSB of ADCS7476 is 0.805 mV.
22
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
Typical Application (continued)
8.2.3 Application Curves
Figure 33. ADCS7476/77 Ideal Transfer Characteristic
Figure 34. ADCS7478 Ideal Transfer Characteristic
9 Power Supply Recommendations
There are three concerns relating to the power supply of these products: the effects of Power Supply Noise upon
the conversion process, the Digital Output Effect Upon Noise upon the conversion process, and Power
Management of the product.
9.1
Power Supply Noise
Because the supply voltage of the ADCS747x is the reference voltage, any noise greater than 1/2 LSB in
amplitude has some effect upon the converter noise performance. This effect is proportional to the input voltage
level. The power supply must receive all the considerations of a reference voltage as far as stability and noise is
concerned. Using the same supply voltage for these devices as is used for digital components leads to degraded
noise performance.
9.2
Digital Output Effect Upon Noise
The charging of any output load capacitance requires current from the digital supply, VDD. The current pulses
required from the supply to charge the output capacitance causes voltage variations at the ADC supply line. If
these variations are large enough, they could degrade SNR and SINAD performance of the ADC. Similarly,
discharging the output capacitance when the digital output goes from a logic high to a logic low dumps current
into the die substrate, causing ground bounce noise in the substrate that degrades noise performance if that
current is large enough. The larger the output capacitance, the more current flows through the device power
supply line and die substrate and the greater is the noise coupled into the analog path.
The first solution to keeping digital noise out of the power supply is to decouple the supply from any other
components or use a separate supply for the ADC. To keep noise out of the supply, keep the output load
capacitance as small as practical. If the load capacitance is greater than 50 pF, use a 100-Ω series resistor at
the ADC output, located as close to the ADC output pin as practical. This limits the charge and discharge current
of the output capacitance and improve noise performance. Because the series resistor and the load capacitance
form a low frequency pole, verify signal integrity when the series resistor is added.
9.3 Power Management
When ADCS747x is operated continuously in normal mode, throughput up to 1 MSPS can be achieved. The user
may trade throughput for power consumption by simply performing fewer conversions per unit time and putting
the ADCS747x into shutdown mode between conversions. This method is not advantageous beyond 350-kSPS
throughput.
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
23
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
Power Management (continued)
A plot of maximum power consumption versus throughput is shown in Figure 35. To calculate the power
consumption for a given throughput, remember that each time the part exits shutdown mode and enters normal
mode, one dummy conversion is required. Generally, the user puts the part into normal mode, execute one
dummy conversion followed by one valid conversion, and then put the part back into shutdown mode. When this
is done, the fraction of time spent in normal mode may be calculated by multiplying the throughput (in samples
per second) by 2 µs, the time taken to perform one dummy and one valid conversion. The power consumption
can then be found by multiplying the fraction of time spent in normal mode by the normal mode power
consumption figure. The power dissipated while the part is in shutdown mode is negligible.
For example, to calculate the power consumption at 300 kSPS with VDD = 5 V, begin by calculating the fraction of
time spent in normal mode: 300,000 samples/second x 2 µs = 0.6, or 60%. The power consumption at 300 kSPS
is then 60% of 17.5 mW (the maximum power consumption at VDD = 5 V) or 10.5 mW.
Figure 35. Maximum Power Consumption vs Throughput
10 Layout
10.1 Layout Guidelines
Capacitive coupling between noisy digital circuitry and sensitive analog circuitry can lead to poor performance.
The solution is to keep the analog and digital circuitry separated from each other and the clock line as short as
possible.
Digital circuits create substantial supply and ground current transients. This digital noise could have significant
impact upon system noise performance. To avoid performance degradation of the ADCS747x due to supply
noise, do not use the same supply for the ADCS747x that is used for digital logic.
Generally, analog and digital lines must cross each other at 90° to avoid crosstalk. However, to maximize
accuracy in high resolution systems, avoid crossing analog and digital lines altogether. It is important to keep
clock lines as short as possible and isolated from ALL other lines, including other digital lines. In addition, the
clock line must also be treated as a transmission line and be properly terminated.
The analog input must be isolated from noisy signal lines to avoid coupling of spurious signals into the input. Any
external component (that is, a filter capacitor) connected between the input pins and ground of the converter or
to the reference input pin and ground must be connected to a very clean point in the ground plane.
TI recommends the use of a single, uniform ground plane and the use of split power planes. The power planes
must be placed within the same board layer. All analog circuitry (input amplifiers, filters, reference components,
and so on) must be placed over the analog power plane. All digital circuitry and I/O lines must be placed over the
digital power plane. Furthermore, all components in the reference circuitry and the input signal chain that are
connected to ground must be connected together with short traces and enter the analog ground plane at a
single, quiet point.
24
Submit Documentation Feedback
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
10.2 Layout Example
Figure 36. Layout Example
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
25
ADCS7476, ADCS7477, ADCS7478
SNAS192G – APRIL 2003 – REVISED MAY 2016
www.ti.com
11 Device and Documentation Support
11.1 Device Support
11.1.1 Device Nomenclature
APERTURE DELAY is the variation in aperture delay from sample to sample. Aperture jitter manifests itself as
noise in the output.
APERTURE JITTER (APERTURE UNCERTAINTY) is the variation in aperture delay from sample to sample.
Aperture jitter manifests itself as noise in the output.
DIFFERENTIAL NON-LINEARITY (DNL) is the measure of the maximum deviation from the ideal step size of 1
LSB.
DUTY CYCLE is the ratio of the time that a repetitive digital waveform is high to the total time of one period. The
specification here refers to the SCLK.
EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE BITS) is another method of specifying Signal-to-Noise
and Distortion or SINAD. ENOB is defined as (SINAD - 1.76) / 6.02 and says that the converter is
equivalent to a perfect ADC of this (ENOB) number of bits.
FULL POWER BANDWIDTH is a measure of the frequency at which the reconstructed output fundamental
drops 3 dB below its low frequency value for a full scale input.
GAIN ERROR is the deviation of the last code transition (111...110) to (111...111) from the ideal (VREF – 1.5 LSB
for ADCS7476 and ADCS7477, VREF – 1 LSB for ADCS7478), after adjusting for offset error.
INTEGRAL NON-LINEARITY (INL) is a measure of the deviation of each individual code from a line drawn from
negative full scale (½ LSB below the first code transition) through positive full scale (½ LSB above
the last code transition). The deviation of any given code from this straight line is measured from
the center of that code value.
INTERMODULATION DISTORTION (IMD) is the creation of additional spectral components as a result of two
sinusoidal frequencies being applied to the ADC input at the same time. It is defined as the ratio of
the power in the either the two second order or all four third order intermodulation products to the
sum of the power in both of the original frequencies. IMD is usually expressed in dBFS.
MISSING CODES are those output codes that never appear at the ADC outputs. ADCS747x is ensured not to
have any missing codes.
OFFSET ERROR is the deviation of the first code transition (000...000) to (000...001) from the ideal (that is,
GND + 0.5 LSB for the ADCS7476 and ADCS7477, and GND + 1 LSB for the ADCS7478).
SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in dB, of the rms value of the input signal to the rms
value of the sum of all other spectral components below one-half the sampling frequency, not
including harmonics or DC.
SIGNAL TO NOISE PLUS DISTORTION (S/N+D or SINAD) Is the ratio, expressed in dB, of the rms value of
the input signal to the rms value of all of the other spectral components below half the clock
frequency, including harmonics but excluding DC.
SPURIOUS FREE DYNAMIC RANGE (SFDR) is the difference, expressed in dB, between the rms values of the
input signal and the peak spurious signal, where a spurious signal is any signal present in the
output spectrum that is not present at the input.
TOTAL HARMONIC DISTORTION (THD) is the ratio, expressed in dBc, of the rms total of the first five harmonic
levels at the output to the level of the fundamental at the output. THD is calculated as:
where
•
•
26
f1 is the RMS power of the fundamental (output) frequency
f2 through f6 are the RMS power in the first 5 harmonic frequencies
Submit Documentation Feedback
(1)
Copyright © 2003–2016, Texas Instruments Incorporated
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
ADCS7476, ADCS7477, ADCS7478
www.ti.com
SNAS192G – APRIL 2003 – REVISED MAY 2016
Device Support (continued)
TOTAL UNADJUSTED ERROR is the worst deviation found from the ideal transfer function. As such, it is a
comprehensive specification which includes full scale error, linearity error, and offset error.
11.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.3 Trademarks
SPI, QSPI, MICROWIRE, E2E are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
Copyright © 2003–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: ADCS7476 ADCS7477 ADCS7478
27
PACKAGE OPTION ADDENDUM
www.ti.com
4-Feb-2016
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
ADCS7476AIMF
NRND
SOT-23
DBV
6
1000
TBD
Call TI
Call TI
-40 to 125
X01A
ADCS7476AIMF/NOPB
ACTIVE
SOT-23
DBV
6
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
X01A
ADCS7476AIMFE/NOPB
ACTIVE
SOT-23
DBV
6
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
X01A
ADCS7476AIMFX
NRND
SOT-23
DBV
6
3000
TBD
Call TI
Call TI
-40 to 125
X01A
ADCS7476AIMFX/NOPB
ACTIVE
SOT-23
DBV
6
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
X01A
ADCS7477AIMF/NOPB
ACTIVE
SOT-23
DBV
6
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 85
X02A
ADCS7477AIMFE/NOPB
ACTIVE
SOT-23
DBV
6
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 85
X02A
ADCS7477AIMFX/NOPB
ACTIVE
SOT-23
DBV
6
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 85
X02A
ADCS7478AIMF/NOPB
ACTIVE
SOT-23
DBV
6
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 85
X03A
ADCS7478AIMFE/NOPB
ACTIVE
SOT-23
DBV
6
250
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 85
X03A
ADCS7478AIMFX/NOPB
ACTIVE
SOT-23
DBV
6
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 85
X03A
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
4-Feb-2016
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
4-Feb-2016
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
ADCS7476AIMF
SOT-23
DBV
6
1000
178.0
8.4
ADCS7476AIMF/NOPB
SOT-23
DBV
6
1000
178.0
ADCS7476AIMFE/NOPB SOT-23
DBV
6
250
178.0
SOT-23
DBV
6
3000
ADCS7476AIMFX/NOPB SOT-23
DBV
6
ADCS7476AIMFX
ADCS7477AIMF/NOPB
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
3.2
3.2
1.4
4.0
8.0
Q3
8.4
3.2
3.2
1.4
4.0
8.0
Q3
8.4
3.2
3.2
1.4
4.0
8.0
Q3
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
3000
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
SOT-23
DBV
6
1000
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
ADCS7477AIMFE/NOPB SOT-23
DBV
6
250
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
ADCS7477AIMFX/NOPB SOT-23
DBV
6
3000
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
SOT-23
DBV
6
1000
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
ADCS7478AIMFE/NOPB SOT-23
ADCS7478AIMF/NOPB
DBV
6
250
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
ADCS7478AIMFX/NOPB SOT-23
DBV
6
3000
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
4-Feb-2016
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
ADCS7476AIMF
SOT-23
DBV
6
1000
210.0
185.0
35.0
ADCS7476AIMF/NOPB
SOT-23
DBV
6
1000
210.0
185.0
35.0
ADCS7476AIMFE/NOPB
SOT-23
DBV
6
250
210.0
185.0
35.0
ADCS7476AIMFX
SOT-23
DBV
6
3000
210.0
185.0
35.0
ADCS7476AIMFX/NOPB
SOT-23
DBV
6
3000
210.0
185.0
35.0
ADCS7477AIMF/NOPB
SOT-23
DBV
6
1000
210.0
185.0
35.0
ADCS7477AIMFE/NOPB
SOT-23
DBV
6
250
210.0
185.0
35.0
ADCS7477AIMFX/NOPB
SOT-23
DBV
6
3000
210.0
185.0
35.0
ADCS7478AIMF/NOPB
SOT-23
DBV
6
1000
210.0
185.0
35.0
ADCS7478AIMFE/NOPB
SOT-23
DBV
6
250
210.0
185.0
35.0
ADCS7478AIMFX/NOPB
SOT-23
DBV
6
3000
210.0
185.0
35.0
Pack Materials-Page 2
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other
changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest
issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and
complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale
supplied at the time of order acknowledgment.
TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms
and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary
to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily
performed.
TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and
applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information
published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or
endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration
and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered
documentation. Information of third parties may be subject to additional restrictions.
Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service
voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice.
TI is not responsible or liable for any such statements.
Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements
concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support
that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which
anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause
harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use
of any TI components in safety-critical applications.
In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to
help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and
requirements. Nonetheless, such components are subject to these terms.
No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties
have executed a special agreement specifically governing such use.
Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in
military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components
which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and
regulatory requirements in connection with such use.
TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of
non-designated products, TI will not be responsible for any failure to meet ISO/TS16949.
Products
Applications
Audio
www.ti.com/audio
Automotive and Transportation
www.ti.com/automotive
Amplifiers
amplifier.ti.com
Communications and Telecom
www.ti.com/communications
Data Converters
dataconverter.ti.com
Computers and Peripherals
www.ti.com/computers
DLP® Products
www.dlp.com
Consumer Electronics
www.ti.com/consumer-apps
DSP
dsp.ti.com
Energy and Lighting
www.ti.com/energy
Clocks and Timers
www.ti.com/clocks
Industrial
www.ti.com/industrial
Interface
interface.ti.com
Medical
www.ti.com/medical
Logic
logic.ti.com
Security
www.ti.com/security
Power Mgmt
power.ti.com
Space, Avionics and Defense
www.ti.com/space-avionics-defense
Microcontrollers
microcontroller.ti.com
Video and Imaging
www.ti.com/video
RFID
www.ti-rfid.com
OMAP Applications Processors
www.ti.com/omap
TI E2E Community
e2e.ti.com
Wireless Connectivity
www.ti.com/wirelessconnectivity
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2016, Texas Instruments Incorporated