AD AD7477AAKSZ-REEL 2.35 v to 5.25 v, 1 msps 12-/10-/8-bit adcs in 6-lead sc70 Datasheet

2.35 V to 5.25 V, 1 MSPS,
12-/10-/8-Bit ADCs in 6-Lead SC70
AD7476A/AD7477A/AD7478A
FEATURES
FUNCTIONAL BLOCK DIAGRAM
Fast throughput rate: 1 MSPS
Specified for VDD of 2.35 V to 5.25 V
Low power
3.6 mW at 1 MSPS with 3 V supplies
12.5 mW at 1 MSPS with 5 V supplies
Wide input bandwidth
71 dB SNR at 100 kHz input frequency
Flexible power/serial clock speed management
No pipeline delays
High speed serial interface
SPI®/QSPI™/MICROWIRE™/DSP compatible
Standby mode: 1 μA maximum
6-lead SC70 package
8-lead MSOP package
Qualified for automotive applications
VDD
VIN
T/H
12-/10-/8-BIT
SUCCESSIVEAPPROXIMATION
ADC
SCLK
CONTROL
LOGIC
SDATA
AD7476A/AD7477A/AD7478A
GND
02930-001
CS
Figure 1.
APPLICATIONS
Battery-powered systems
Personal digital assistants
Medical instruments
Mobile communications
Instrumentation and control systems
Data acquisition systems
High speed modems
Optical sensors
GENERAL DESCRIPTION
The AD7476A/AD7477A/AD7478A are 12-bit, 10-bit, and 8-bit
high speed, low power, successive-approximation analog-todigital converters (ADCs), respectively. The parts operate from
a single 2.35 V to 5.25 V power supply and feature throughput
rates up to 1 MSPS. The parts contain a low noise, wide
bandwidth track-and-hold amplifier that can handle input
frequencies in excess of 13 MHz. The conversion process and
data acquisition are controlled using CS and the serial clock,
allowing the devices to interface with microprocessors or DSPs.
The input signal is sampled on the falling edge of CS, and the
conversion is also initiated at this point. There are no pipeline
delays associated with the parts. The AD7476A/AD7477A/
AD7478A use advanced design techniques to achieve low power
dissipation at high throughput rates. The reference for the part
is taken internally from VDD to allow the widest dynamic input
range to the ADC. Thus, the analog input range for the part is
0 V to VDD. The conversion rate is determined by the SCLK.
PRODUCT HIGHLIGHTS
1.
First 12-/10-/8-bit ADCs in a SC70 package.
2.
High throughput with low power consumption.
3.
Flexible power/serial clock speed management. The
conversion rate is determined by the serial clock, allowing
the conversion time to be reduced through the serial clock
speed increase. This allows the average power consumption
to be reduced when a power-down mode is used while not
converting. The parts also feature a power-down mode to
maximize power efficiency at lower throughput rates.
Current consumption is 1 μA maximum and 50 nA
typically when in power-down mode.
4.
Reference derived from the power supply.
5.
No pipeline delay. The parts feature a standard successive
approximation ADC with accurate control of the sampling
instant via a CS input and once-off conversion control.
Rev. F
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2002–2011 Analog Devices, Inc. All rights reserved.
AD7476A/AD7477A/AD7478A
TABLE OF CONTENTS
Features .............................................................................................. 1
Typical Connection Diagram ....................................................... 16
Applications ....................................................................................... 1
Analog Input ............................................................................... 16
Functional Block Diagram .............................................................. 1
Digital Inputs .............................................................................. 17
General Description ......................................................................... 1
Modes of Operation ....................................................................... 18
Product Highlights ........................................................................... 1
Normal Mode.............................................................................. 18
Revision History ............................................................................... 2
Power-Down Mode .................................................................... 18
Specifications..................................................................................... 3
Power-Up Time .......................................................................... 18
AD7476A Specifications .............................................................. 3
Power vs. Throughput Rate ........................................................... 20
AD7477A Specifications .............................................................. 5
Serial Interface ................................................................................ 21
AD7478A Specifications .............................................................. 6
AD7478A in a 12 SCLK Cycle Serial Interface....................... 22
Timing Specifications .................................................................. 8
Microprocessor Interfacing ........................................................... 23
Absolute Maximum Ratings.......................................................... 10
AD7476A/AD7477A/AD7478A to TMS320C541 Interface 23
ESD Caution ................................................................................ 10
AD7476A/AD7477A/AD7478A to ADSP-218x Interface .... 23
Pin Configurations and Function Descriptions ......................... 11
AD7476A/AD7477A/AD7478A to DSP563xx Interface ...... 24
Typical Performance Characteristics ........................................... 12
Application Hints ........................................................................... 25
Terminology .................................................................................... 14
Grounding and Layout .............................................................. 25
Theory of Operation ...................................................................... 15
Evaluating the AD7476A/AD7477A Performance ............... 25
Circuit Information .................................................................... 15
Outline Dimensions ....................................................................... 26
The Converter Operation .......................................................... 15
Ordering Guide .......................................................................... 26
ADC Transfer Function ............................................................. 15
Automotive Products ................................................................. 27
REVISION HISTORY
1/11—Rev. E to Rev. F
Changes to Features Section............................................................ 1
Changes to Ordering Guide .......................................................... 26
Added Automotive Products Section .......................................... 27
2/09—Rev. D to Rev. E
Changes to Features.......................................................................... 1
Changes to Ordering Guide .......................................................... 26
4/06—Rev. C to Rev. D
Updated Format .................................................................. Universal
Changes to Ordering Guide .......................................................... 26
Rev. F | Page 2 of 28
AD7476A/AD7477A/AD7478A
SPECIFICATIONS
AD7476A SPECIFICATIONS
VDD = 2.35 V to 5.25 V, fSCLK = 20 MHz, fSAMPLE = 1 MSPS, TA = TMIN to TMAX, unless otherwise noted. 1
Table 1.
Parameter
DYNAMIC PERFORMANCE
Signal-to-Noise + Distortion (SINAD)3
Signal-to-Noise Ratio (SNR)3
Total Harmonic Distortion (THD)3
Peak Harmonic or Spurious Noise (SFDR)3
Intermodulation Distortion (IMD)3
Second-Order Terms
Third-Order Terms
Aperture Delay
Aperture Jitter
Full Power Bandwidth
DC ACCURACY
Resolution
Integral Nonlinearity3
A Grade2
B Grade2
Y Grade2
Unit
70
69
71.5
69
68
71
70
70
69
–80
–82
70
69
71.5
69
68
71
70
70
69
–80
–82
70
69
71.5
69
68
71
70
70
69
–80
–82
dB min
dB min
dB typ
dB min
dB min
dB min
dB min
dB min
dB min
dB typ
dB typ
–84
–84
10
30
13.5
2
–84
–84
10
30
13.5
2
–84
–84
10
30
13.5
2
dB typ
dB typ
ns typ
ps typ
MHz typ
MHz typ
12
12
±1.5
12
±1.5
–0.9/+1.5
–0.9/+1.5
±1.5
±0.2
±1.5
±0.5
±2
±1.5
±0.2
±1.5
±0.5
±2
Bits
LSB max
LSB typ
LSB max
LSB typ
LSB max
LSB typ
LSB max
LSB typ
LSB max
0 to VDD
±0.5
20
0 to VDD
±0.5
20
0 to VDD
±0.5
20
V
μA max
pF typ
2.4
1.8
0.8
0.4
±0.5
±10
5
2.4
1.8
0.8
0.4
±0.5
±10
5
2.4
1.8
0.8
0.4
±0.5
±10
5
V min
V min
V max
V max
μA max
nA typ
pF max
±0.75
Differential Nonlinearity
±0.75
Offset Error3, 5
±1.5
Gain Error3, 5
±1.5
Total Unadjusted Error (TUE)3, 5
ANALOG INPUT
Input Voltage Range
DC Leakage Current
Input Capacitance
LOGIC INPUTS
Input High Voltage, VINH
Input Low Voltage, VINL
Input Current, IIN, SCLK Pin
Input Current, IIN, CS Pin
Input Capacitance, CIN6
Rev. F | Page 3 of 28
Test Conditions/Comments
fIN = 100 kHz sine wave
VDD = 2.35 V to 3.6 V, TA = 25°C
VDD = 2.4 V to 3.6 V
VDD = 2.35 V to 3.6 V
VDD = 4.75 V to 5.25 V, TA = 25°C
VDD = 4.75 V to 5.25 V
VDD = 2.35 V to 3.6 V, TA = 25°C
VDD = 2.4 V to 3.6 V
VDD = 4.75 V to 5.25 V, TA = 25°C
VDD = 4.75 V to 5.25 V
fa = 100.73 kHz, fb = 90.72 kHz
fa = 100.73 kHz, fb = 90.72 kHz
@ 3 dB
@ 0.1 dB
B and Y grades4
Guaranteed no missed codes to 12 bits
Track-and-hold in track; 6 pF typ when in hold
VDD = 2.35 V
VDD = 5 V
VDD = 3 V
Typically 10 nA, VIN = 0 V or VDD
AD7476A/AD7477A/AD7478A
Parameter
LOGIC OUTPUTS
Output High Voltage, VOH
Output Low Voltage, VOL
Floating-State Leakage Current
Floating-State Output Capacitance6
Output Coding
CONVERSION RATE
Conversion Time
Track-and-Hold Acquisition Time3
Throughput Rate
POWER REQUIREMENTS
VDD
IDD
Normal Mode (Static)
Normal Mode (Operational)
Full Power-Down Mode (Static)
Full Power-Down Mode (Dynamic)
Power Dissipation7
Normal Mode (Operational)
Full Power-Down Mode
A Grade2
B Grade2
Y Grade2
Unit
Test Conditions/Comments
VDD – 0.2
VDD – 0.2
VDD – 0.2
0.4
0.4
0.4
±1
±1
±1
5
5
5
Straight (Natural) Binary
V min
V max
μA max
pF max
ISOURCE = 200 μA; VDD = 2.35 V to 5.25 V
ISINK = 200 μA
800
250
1
800
250
1
800
250
1
ns max
ns max
MSPS max
16 SCLK cycles
2.35/5.25
2.35/5.25
2.35/5.25
V min/max
2.5
1.2
3.5
1.7
1
0.6
0.3
17.5
5.1
5
3
2.5
1.2
3.5
1.7
1
0.6
0.3
17.5
5.1
5
3
2.5
1.2
3.5
1.7
1
0.6
0.3
17.5
5.1
5
3
mA typ
mA typ
mA max
mA max
μA max
mA typ
mA typ
mW max
mW max
μW max
μW max
Temperature ranges are as follows: A, B grades from –40°C to +85°C, Y grade from –40°C to +125°C.
Operational from VDD = 2.0 V, with input low voltage (VINL) 0.35 V maximum.
See the Terminology section.
4
B and Y grades, maximum specifications apply as typical figures when VDD = 4.75 V to 5.25 V.
5
SC70 values guaranteed by characterization.
6
Guaranteed by characterization.
7
See the Power vs. Throughput Rate section.
1
2
3
Rev. F | Page 4 of 28
See Serial Interface section
Digital I/Ps = 0 V or VDD
VDD = 4.75 V to 5.25 V, SCLK on or off
VDD = 2.35 V to 3.6 V, SCLK on or off
VDD = 4.75 V to 5.25 V, fSAMPLE = 1 MSPS
VDD = 2.35 V to 3.6 V, fSAMPLE = 1 MSPS
Typically 50 nA
VDD = 5 V, fSAMPLE = 100 kSPS
VDD = 3 V, fSAMPLE = 100 kSPS
VDD = 5 V, fSAMPLE = 1 MSPS
VDD = 3 V, fSAMPLE = 1 MSPS
VDD = 5 V
VDD = 3 V
AD7476A/AD7477A/AD7478A
AD7477A SPECIFICATIONS
VDD = 2.35 V to 5.25 V, fSCLK = 20 MHz, fSAMPLE = 1 MSPS, TA = TMIN to TMAX, unless otherwise noted.1
Table 2.
Parameter
DYNAMIC PERFORMANCE
Signal-to-Noise + Distortion (SINAD)3
Total Harmonic Distortion (THD)3
Peak Harmonic or Spurious Noise (SFDR)3
Intermodulation Distortion (IMD)3
Second-Order Terms
Third-Order Terms
Aperture Delay
Aperture Jitter
Full Power Bandwidth
DC ACCURACY
Resolution
Integral Nonlinearity
Differential Nonlinearity
Offset Error3, 4
Gain Error3, 4
Total Unadjusted Error (TUE)3, 4
ANALOG INPUT
Input Voltage Range
DC Leakage Current
Input Capacitance
LOGIC INPUTS
Input High Voltage, VINH
Input Low Voltage, VINL
Input Current, IIN, SCLK Pin
Input Current, IIN, CS Pin
Input Capacitance, CIN5
LOGIC OUTPUTS
Output High Voltage VOH
Output Low Voltage, VOL
Floating-State Leakage Current
Floating-State Output Capacitance5
Output Coding
CONVERSION RATE
Conversion Time
Track-and-Hold Acquisition Time3
Throughput Rate
A Grade2
Unit
61
–72
–73
dB min
dB max
dB max
–82
–82
10
30
13.5
2
dB typ
dB typ
ns typ
ps typ
MHz typ
MHz typ
10
±0.5
±0.5
±1
±1
±1.2
Bits
LSB max
LSB max
LSB max
LSB max
LSB max
0 to VDD
±0.5
20
V
µA max
pF typ
2.4
1.8
0.8
0.4
±0.5
±10
5
V min
V min
V max
V max
μA max
nA typ
pF max
Test Conditions/Comments
fIN = 100 kHz sine wave
fa = 100.73 kHz, fb = 90.7 kHz
fa = 100.73 kHz, fb = 90.7 kHz
@ 3 dB
@ 0.1 dB
Guaranteed no missed codes to 10 bits
Track-and-hold in track; 6 pF typ when in hold
VDD = 2.35 V
VDD = 5 V
VDD = 3 V
Typically 10 nA, VIN = 0 V or VDD
VDD – 0.2
V min
0.4
V max
±1
μA max
5
pF max
Straight (Natural) Binary
ISOURCE = 200 μA, VDD = 2.35 V to 5.25 V
ISINK = 200 μA
700
250
1
14 SCLK cycles with SCLK at 20 MHz
ns max
ns max
MSPS max
Rev. F | Page 5 of 28
AD7476A/AD7477A/AD7478A
Parameter
POWER REQUIREMENTS
VDD
IDD
Normal Mode (Static)
Normal Mode (Operational)
Full Power-Down Mode (Static)
Full Power-Down Mode (Dynamic)
Power Dissipation6
Normal Mode (Operational)
Full Power-Down Mode
A Grade2
Unit
Test Conditions/Comments
2.35/5.25
V min/max
2.5
1.2
3.5
1.7
1
0.6
0.3
17.5
5.1
5
mA typ
mA typ
mA max
mA max
μA max
mA typ
mA typ
mW max
mW max
μW max
Digital I/Ps = 0 V or VDD
VDD = 4.75 V to 5.25 V, SCLK on or off
VDD = 2.35 V to 3.6 V, SCLK on or off
VDD = 4.75 V to 5.25 V, fSAMPLE = 1 MSPS
VDD = 2.35 V to 3.6 V, fSAMPLE = 1 MSPS
Typically 50 nA
VDD = 5 V, fSAMPLE = 100 kSPS
VDD = 3 V, fSAMPLE = 100 kSPS
VDD = 5 V, fSAMPLE = 1 MSPS
VDD = 3 V, fSAMPLE = 1 MSPS
VDD = 5 V
Temperature range is from –40°C to +85°C.
Operational from VDD = 2.0 V, with input high voltage (VINH) 1.8 V minimum.
3
See the Terminology section.
4
SC70 values guaranteed by characterization.
5
Guaranteed by characterization.
6
See the Power vs. Throughput Rate section.
1
2
AD7478A SPECIFICATIONS
VDD = 2.35 V to 5.25 V, fSCLK = 20 MHz, fSAMPLE = 1 MSPS, TA = TMIN to TMAX, unless otherwise noted.1
Table 3.
Parameter
DYNAMIC PERFORMANCE
Signal-to-Noise + Distortion (SINAD)3
Total Harmonic Distortion (THD)3
Peak Harmonic or Spurious Noise (SFDR)3
Intermodulation Distortion (IMD)3
Second-Order Terms
Third-Order Terms
Aperture Delay
Aperture Jitter
Full Power Bandwidth
DC ACCURACY
Resolution
Integral Nonlinearity3
Differential Nonlinearity3
Offset Error3, 4
Gain Error3, 4
Total Unadjusted Error (TUE)3, 4
ANALOG INPUT
Input Voltage Range
DC Leakage Current
Input Capacitance
A Grade2
Unit
Test Conditions/Comments
fIN = 100 kHz sine wave
49
–65
–65
dB min
dB max
dB max
–76
–76
10
30
13.5
2
dB typ
dB typ
ns typ
ps typ
MHz typ
MHz typ
8
±0.3
±0.3
±0.3
±0.3
±0.5
Bits
LSB max
LSB max
LSB max
LSB max
LSB max
0 to VDD
±0.5
20
V
μA max
pF typ
Rev. F | Page 6 of 28
fa = 100.73 kHz, fb = 90.7 kHz
fa = 100.73 kHz, fb = 90.7 kHz
@ 3 dB
@ 0.1 dB
Guaranteed no missed codes to eight bits
Track-and-hold in track; 6 pF typ when in hold
AD7476A/AD7477A/AD7478A
Parameter
LOGIC INPUTS
Input High Voltage, VINH
Input Low Voltage, VINL
Input Current, IIN, SCLK Pin
Input Current, IIN, CS Pin
Input Capacitance, CIN5
LOGIC OUTPUTS
Output High Voltage, VOH
Output Low Voltage, VOL
Floating-State Leakage Current
Floating-State Output Capacitance5
Output Coding
CONVERSION RATE
Conversion Time
Track-and-Hold Acquisition Time3
Throughput Rate
POWER REQUIREMENTS
VDD
IDD
Normal Mode (Static)
Normal Mode (Operational)
Full Power-Down Mode (Static)
Full Power-Down Mode (Dynamic)
Power Dissipation6
Normal Mode (Operational)
Full Power-Down Mode
A Grade2
Unit
2.4
1.8
0.8
0.4
±0.5
±10
5
V min
V min
V max
V max
μA max
nA typ
pF max
Test Conditions/Comments
VDD = 2.35 V
VDD = 5 V
VDD = 3 V
Typically 10 nA, VIN = 0 V or VDD
VDD – 0.2
V min
0.4
V max
±1
μA max
5
pF max
Straight (Natural) Binary
ISOURCE = 200 μA, VDD = 2.35 V to 5.25 V
ISINK = 200 μA
600
225
1.2
ns max
ns max
MSPS max
12 SCLK cycles with SCLK at 20 MHz
2.35/5.25
V min/max
2.5
1.2
3.5
1.7
1
0.6
0.3
17.5
5.1
5
mA typ
mA typ
mA max
mA max
μA max
mA typ
mA typ
mW max
mW max
μW max
Temperature range is from –40°C to +85°C.
Operational from VDD = 2.0 V, with input high voltage (VINH) 1.8 V minimum.
3
See the Terminology section.
4
SC70 values guaranteed by characterization.
5
Guaranteed by characterization.
6
See the Power vs. Throughput Rate section.
1
2
Rev. F | Page 7 of 28
Digital I/Ps = 0 V or VDD
VDD = 4.75 V to 5.25 V, SCLK on or off
VDD = 2.35 V to 3.6 V, SCLK on or off
VDD = 4.75 V to 5.25 V
VDD = 2.35 V to 3.6 V
Typically 50 nA
VDD = 5 V, fSAMPLE = 100 kSPS
VDD = 3 V, fSAMPLE = 100 kSPS
VDD = 5 V
VDD = 3 V
VDD = 5 V
AD7476A/AD7477A/AD7478A
TIMING SPECIFICATIONS
VDD = 2.35 V to 5.25 V; TA = TMIN to TMAX, unless otherwise noted.1
Table 4.
Parameter
fSCLK2
tCONVERT
tQUIET
t1
t2
t34
t44
t5
t6
t75
t86
tPOWER-UP7
Limit at TMIN, TMAX
10
20
20
16 × tSCLK
14 × tSCLK
12 × tSCLK
50
Unit
kHz min3
kHz min3
MHz max
ns min
10
10
22
40
0.4 tSCLK
0.4 tSCLK
ns min
ns min
ns max
ns max
ns min
ns min
10
9.5
7
36
t7 values also apply to t8 minimum values
1
ns min
ns min
ns min
ns max
ns min
μs max
Description
A, B grades
Y grade
AD7476A
AD7477A
AD7478A
Minimum quiet time required between bus relinquish
and start of next conversion
Minimum CS pulse width
CS to SCLK setup time
Delay from CS until SDATA three-state disabled
Data access time after SCLK falling edge
SCLK low pulse width
SCLK high pulse width
SCLK to data valid hold time
VDD ≤ 3.3 V
3.3 V < VDD ≤ 3.6 V
VDD > 3.6 V
SCLK falling edge to SDATA high impedance
SCLK falling edge to SDATA high impedance
Power-up time from full power-down
Guaranteed by characterization. All input signals are specified with tr = tf = 5 ns (10% to 90% of VDD) and timed from a voltage level of 1.6 V.
Mark/space ratio for the SCLK input is 40/60 to 60/40.
3
Minimum fSCLK at which specifications are guaranteed.
4
Measured with the load circuit shown in Figure 2, and defined as the time required for the output to cross 0.8 V or 1.8 V when VDD = 2.35 V, and
0.8 V or 2.0 V for VDD > 2.35 V.
5
Measured with a 50 pF load capacitor.
6
t8 is derived from the measured time taken by the data outputs to change 0.5 V when loaded with the circuit shown in Figure 2. The measured number is then
extrapolated back to remove the effects of charging or discharging the 50 pF capacitor. Therefore, the time, t8, quoted in the timing characteristics is the true bus
relinquish time of the part and is independent of the bus loading.
7
See the Power-Up Time section.
1
2
Rev. F | Page 8 of 28
AD7476A/AD7477A/AD7478A
Timing Diagrams
Timing Example 2
200µA
t2 + 12.5 (1/fSCLK) + tACQ = 3.174 µs
1.6V
CL
50pF
200µA
where:
02930-002
TO OUTPUT
PIN
Having fSCLK = 5 MHz and a throughput is 315 kSPS yields a
cycle time of
IOL
IOH
t2 = 10 ns min, this leaves tACQ to be 664 ns. This 664 ns satisfies
the requirement of 250 ns for tACQ.
Figure 2. Load Circuit for Digital Output Timing Specifications
Timing Example 1
From Figure 4, tACQ is comprised of
Having fSCLK = 20 MHz and a throughput of 1 MSPS, a cycle
time of
2.5 (1/fSCLK) + t8 + tQUIET, t8 = 36 ns maximum
This allows a value of 128 ns for tQUIET, satisfying the minimum
requirement of 50 ns.
t2 + 12.5 (1/fSCLK) + tACQ = 1 µs
where:
In this example and with other, slower clock values, the signal
may already be acquired before the conversion is complete, but
it is still necessary to leave 50 ns minimum tQUIET between
conversions. In Example 2, acquire the signal fully at
approximately Point C in Figure 4.
t2 = 10 ns min, leaving tACQ to be 365 ns. This 365 ns satisfies the
requirement of 250 ns for tACQ.
From Figure 4, tACQ is comprised of
2.5 (1/fSCLK) + t8 + tQUIET
where:
t8 = 36 ns maximum. This allows a value of 204 ns for tQUIET,
satisfying the minimum requirement of 50 ns.
t1
CS
2
1
t3
SDATA
THREESTATE
B
5
t4
ZERO
Z
4
3
ZERO
13
14
t7
ZERO
DB11
15
16
t5
DB10
DB2
t8
DB1
tQUIET
DB0
THREE-STATE
4 LEADING ZEROS
02930-003
SCLK
tCONVERT
t6
t2
Figure 3. AD7476A Serial Interface Timing Diagram
CS
tCONVERT
SCLK
B
1
2
3
5
4
13
C
14
15
16
t8
tACQ
12.5(1/fSCLK)
1/THROUGHPUT
Figure 4. Serial Interface Timing Example
Rev. F | Page 9 of 28
tQUIET
02930-004
t2
AD7476A/AD7477A/AD7478A
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.1
Table 5.
Parameter
VDD to GND
Analog Input Voltage to GND
Digital Input Voltage to GND
Digital Output Voltage to GND
Input Current to Any Pin Except Supplies
Operating Temperature Range
Commercial (A and B Grades)
Industrial (Y Grade)
Storage Temperature Range
Junction Temperature
MSOP Package
θJA Thermal Impedance
θJC Thermal Impedance
SC70 Package
θJA Thermal Impedance
θJC Thermal Impedance
Lead Temperature, Soldering
Reflow (10 sec to 30 sec)
Pb-Free Temperature Soldering
Reflow
ESD
1
Ratings
–0.3 V to +7 V
–0.3 V to VDD + 0.3 V
–0.3 V to +7 V
–0.3 V to VDD + 0.3 V
10 mA
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
–40°C to +85°C
–40°C to +125°C
–65°C to +150°C
150°C
205.9°C/W
43.74°C/W
340.2°C/W
228.9°C/W
235 (0/+5)°C
255 (0/+5)°C
3.5 kV
Transient currents of up to 100 mA do not cause SCR latch-up.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Rev. F | Page 10 of 28
AD7476A/AD7477A/AD7478A
VIN 3
AD7476A/
AD7477A/
AD7478A
6 CS
VDD 1
5 SDATA
4 SCLK
TOP VIEW
(Not to Scale)
SDATA 2
02930-005
VDD 1
GND 2
AD7476A/
AD7477A/
AD7478A
8
VIN
7
GND
6 SCLK
CS 3
TOP VIEW
NC 4 (Not to Scale) 5 NC
NC = NO CONNECT
02930-006
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
Figure 6. 8-Lead MSOP Pin Configuration
Figure 5. 6-Lead SC70 Pin Configuration
Table 6. Pin Function Descriptions
Mnemonic
CS
VDD
GND
VIN
SDATA
SCLK
NC
Description
Chip Select. Active low logic input. This input provides the dual function of initiating conversions on the
AD7476A/AD7477A/AD7478A and also frames the serial data transfer.
Power Supply Input. The VDD range for AD7476A/AD7477A/AD7478A is from 2.35 V to 5.25 V.
Analog Ground. Ground reference point for all circuitry on AD7476A/AD7477A/AD7478A. Refer all analog input signals to this
GND voltage.
Analog Input. Single-ended analog input channel. The input range is 0 V to VDD.
Data Out. Logic output. The conversion result from AD7476A/AD7477A/AD7478A is provided on this output as a serial data
stream. The bits are clocked out on the falling edge of the SCLK input. The data stream from the AD7476A consists of four
leading zeros followed by 12 bits of conversion data that are provided MSB first. The data stream from the AD7477A consists
of four leading zeros followed by 10 bits of conversion data followed by two trailing zeros, provided MSB first. The data stream
from the AD7478A consists of four leading zeros followed by 8 bits of conversion data followed by four trailing zeros that are
provided MSB first.
Serial Clock. Logic input. SCLK provides the serial clock for accessing data from the part. This clock input is also used as the
clock source for the conversion process of AD7476A/AD7477A/AD7478A.
No Connect.
Rev. F | Page 11 of 28
AD7476A/AD7477A/AD7478A
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 7, Figure 8, and Figure 9 each show a typical FFT plot for
the AD7476A, AD7477A, and AD7478A, respectively, at a
1 MSPS sample rate and 100 kHz input frequency. Figure 10
shows the signal-to-(noise + distortion) ratio performance vs.
the input frequency for various supply voltages while sampling
at 1 MSPS with an SCLK frequency of 20 MHz for the
AD7476A.
Figure 11 and Figure 12 show INL and DNL performance for
the AD7476A. Figure 13 shows a graph of the total harmonic
distortion vs. the analog input frequency for different source
impedances when using a supply voltage of 3.6 V and sampling
at a rate of 1 MSPS (see the Analog Input section). Figure 14
shows a graph of the total harmonic distortion vs. the analog
input signal frequency for various supply voltages while
sampling at 1 MSPS with an SCLK frequency of 20 MHz.
5
5
8192 POINT FFT
VDD = 2.7V
fSAMPLE = 1MSPS
fIN = 100kHz
SINAD = 72.05dB
THD = –82.87dB
SFDR = –87.24dB
–15
–15
–25
SNR (dB)
–55
–75
–35
–45
–55
–65
–75
02930-007
–95
–115
0
50
100
150
200 250 300 350
FREQUENCY (kHz)
400
450
02930-009
SNR (dB)
–35
8192 POINT FFT
VDD = 2.35V
fSAMPLE = 1MSPS
fIN = 100kHz
SINAD = 49.77dB
THD = –75.51dB
SFDR = –70.71dB
–5
–85
–95
500
0
Figure 7. AD7476A Dynamic Performance at 1 MSPS
50
100
150
200 250 300 350
FREQUENCY (kHz)
400
450
500
Figure 9. AD7478A Dynamic Performance at 1 MSPS
–66
8192 POINT FFT
VDD = 2.35V
fSAMPLE = 1MSPS
fIN = 100kHz
SINAD = 61.67dB
THD = –79.59dB
SFDR = –82.93dB
SNR (dB)
–25
–67
–68
SINAD (dB)
–5
–45
VDD = 2.7V
–69
VDD = 2.35V
–70
VDD = 5.25V
–71
–65
–72
02930-008
–73
–105
0
50
100
150
200 250 300 350
FREQUENCY (kHz)
400
450
02930-010
VDD = 4.75V
–85
VDD = 3.6V
–74
10
500
100
FREQUENCY (kHz)
1000
Figure 10. AD7476A SINAD vs. Input Frequency at 1 MSPS
Figure 8. AD7477A Dynamic Performance at 1 MSPS
Rev. F | Page 12 of 28
AD7476A/AD7477A/AD7478A
1.0
0
VDD = 3.6V
VDD = 2.35V
TEMP = 25°C
fSAMPLE = 1MSPS
0.8
0.6
–10
–20
–30
0.2
THD (dB)
0
–0.2
–40
RIN = 1kΩ
–50
–60
RIN = 130Ω
–70
02930-011
–0.6
–0.8
–1.0
0
512
1024
1536
2048
CODE
2560
3072
3584
RIN = 0Ω
–90
4096
Figure 11. AD7476A INL Performance
RIN = 13Ω
–80
10
100
INPUT FREQUENCY (kHz)
02930-013
–0.4
1000
Figure 13. THD vs. Analog Input Frequency for Various Source Impedances
1.0
–60
VDD = 2.35V
TEMP = 25°C
fSAMPLE = 1MSPS
0.8
0.6
–65
VDD = 2.35V
0.4
–70
THD (dB)
0.2
0
–0.2
VDD = 2.7V
–75
VDD = 4.75V
–80
–0.4
–0.6
–85
02930-012
DNL ERROR (LSB)
RIN = 10kΩ
–0.8
–1.0
0
512
1024
1536
2048
CODE
2560
3072
Figure 12. AD7476A DNL Performance
3584
VDD = 5.25V
VDD = 3.6V
–90
4096
10
100
INPUT FREQUENCY (kHz)
02930-014
INL ERROR (LSB)
0.4
1000
Figure 14. THD vs. Analog Input Frequency for Various Supply Voltages
Rev. F | Page 13 of 28
AD7476A/AD7477A/AD7478A
TERMINOLOGY
Integral Nonlinearity (INL)
INL is the maximum deviation from a straight line passing
through the endpoints of the ADC transfer function. For the
AD7476A/AD7477A/AD7478A, the endpoints of the transfer
function are zero scale (1 LSB below the first code transition),
and full scale (1 LSB above the last code transition).
Total Harmonic Distortion (THD)
Total harmonic distortion is the ratio of the rms sum of
harmonics to the fundamental. It is defined as
Differential Nonlinearity (DNL)
DNL is the difference between the measured and the ideal
1 LSB change between any two adjacent codes in the ADC.
where V1 is the rms amplitude of the fundamental, and V2, V3,
V4, V5, and V6 are the rms amplitudes of the second through the
sixth harmonics.
Offset Error
This is the deviation of the first code transition (00 . . . 000) to
(00 . . . 001) from the ideal, that is, AGND + 1 LSB.
Peak Harmonic or Spurious Noise (SFDR)
Peak harmonic or spurious noise is defined as the ratio of the rms
value of the next largest component in the ADC output spectrum
(up to fS/2 and excluding dc) to the rms value of the fundamental.
Normally, the value of this specification is determined by the largest
harmonic in the spectrum. For ADCs where the harmonics are
buried in the noise floor, it is a noise peak.
Gain Error
This is the deviation of the last code transition (111 . . . 110) to
(111 . . . 111) from the ideal, that is, VREF – 1 LSB after the offset
error has been adjusted out.
Track-and-Hold Acquisition Time
The track-and-hold amplifier returns to track mode at the end
of a conversion. The track-and-hold acquisition time is the time
required for the output of the track-and-hold amplifier to reach
its final value, within 0.5 LSB, after the end of conversion. See
the Serial Interface section for more details.
Signal-to-(Noise + Distortion) Ratio (SINAD)
This is the measured ratio of signal-to-(noise + distortion) at
the output of the ADC. The signal is the rms amplitude of the
fundamental. Noise is the sum of all nonfundamental signals up
to half the sampling frequency (fS/2), excluding dc. The ratio is
dependent on the number of quantization levels in the digitization process; the more levels, the smaller the quantization noise.
The theoretical signal-to-(noise + distortion) ratio for an ideal
N-bit converter with a sine wave input is given by signal-to(noise + distortion) = (6.02 N + 1.76) dB. Thus, it is 74 dB for a
12-bit converter, 62 dB for a 10-bit converter, and 50 dB for an
8-bit converter.
THD(dB) = 20 log
V22 + V32 + V42 + V52 + V62
V1
Intermodulation Distortion (IMD)
With inputs consisting of sine waves at two frequencies, fa and
fb, any active device with nonlinearities create distortion
products at sum and difference frequencies of mfa, nfb, where
m and n = 0, 1, 2, 3, and so on. Intermodulation distortion
terms are those for which neither m nor n are equal to zero. For
example, the second-order terms include (fa + fb) and (fa – fb),
and the third-order terms include (2fa + fb), (2fa – fb), (fa + 2fb),
and (fa – 2fb).
The AD7476A/AD7477A/AD7478A are tested using the CCIF
standard where two input frequencies are used (see fa and fb in
the Specifications section). In this case, the second-order terms
are usually distanced in frequency from the original sine waves,
while the third-order terms are usually at a frequency close to the
input frequencies. As a result, the second- and third-order terms
are specified separately. The calculation of the intermodulation
distortion is per the THD specification, where it is the ratio of
the rms sum of the individual distortion products to the rms
amplitude of the sum of the fundamentals expressed in decibels.
Total Unadjusted Error (TUE)
This is a comprehensive specification that includes the gain,
linearity, and offset errors.
Rev. F | Page 14 of 28
AD7476A/AD7477A/AD7478A
THEORY OF OPERATION
THE CONVERTER OPERATION
CHARGE
REDISTRIBUTION
DAC
VIN
SW1
B
ACQUISITION
PHASE
ADC TRANSFER FUNCTION
The output coding of the AD7476A/AD7477A/AD7478A is
straight binary. The designed code transitions occur at the
successive integer LSB values, that is, 1 LSB, 2 LSB, and so on.
The LSB size is VDD/4096 for the AD7476A, VDD/1024 for the
AD7477A, and VDD/256 for the AD7478A. The ideal transfer
characteristic for the AD7476A/AD7477A/AD7478A is shown
in Figure 17.
COMPARATOR
AGND
VDD/2
111...111
111...110
111...000
1LSB = V DD/4096 (AD7476A)
1LSB = V DD/1024 (AD7477A)
1LSB = V DD/256 (AD7478A)
011...111
000...010
000...001
000...000
CONTROL
LOGIC
SW2
COMPARATOR
Figure 16. ADC Conversion Phase
SAMPLING
CAPACITOR
SW1
B
CONTROL
LOGIC
SW2
VDD/2
02930-015
VIN
CONVERSION
PHASE
AGND
CHARGE
REDISTRIBUTION
DAC
A
SAMPLING
CAPACITOR
A
ADC CODE
AD7476A/AD7477A/AD7478A are successive approximation,
analog-to-digital converters based around a charge redistribution DAC. Figure 15 and Figure 16 show simplified schematics
of the ADC. Figure 15 shows the ADC during its acquisition
phase. SW2 is closed and SW1 is in Position A, the comparator
is held in a balanced condition, and the sampling capacitor
acquires the signal on VIN.
When the ADC starts a conversion (see Figure 16), SW2 opens
and SW1 moves to Position B, causing the comparator to become
unbalanced. The control logic and the charge redistribution
DAC are used to add and subtract fixed amounts of charge from
the sampling capacitor to bring the comparator back into a
balanced condition. When the comparator is rebalanced, the
conversion is complete. The control logic generates the ADC
output code. Figure 17 shows the ADC transfer function.
02930-016
The AD7476A/AD7477A/AD7478A are fast, micropower,
12-/10-/8-bit, single-supply analog-to-digital converters (ADCs),
respectively. The parts can be operated from a 2.35 V to 5.25 V
supply. When operated from either a 5 V supply or a 3 V supply,
the AD7476A/AD7477A/AD7478A are capable of throughput
rates of 1 MSPS when provided with a 20 MHz clock. The
AD7476A/AD7477A/AD7478A provide the user with an onchip, track-and-hold ADC and a serial interface housed in a
tiny 6-lead SC70 or 8-lead MSOP package, offering the user
considerable space-saving advantages over alternative solutions.
The serial clock input accesses data from the part but also provides the clock source for the successive-approximation ADC.
The analog input range is 0 V to VDD. The ADC does not require
an external reference or an on-chip reference. The reference for
the AD7476A/AD7477A/AD7478A is derived from the power
supply and, thus, gives the widest dynamic input range. The
AD7476A/AD7477A/AD7478A also feature a power-down
option to allow power saving between conversions. The powerdown feature is implemented across the standard serial interface,
as described in the Modes of Operation section.
Figure 15. ADC Acquisition Phase
Rev. F | Page 15 of 28
0V 1LSB
ANALOG INPUT
+VDD – 1LSB
Figure 17. AD7476A/AD7477A/AD7478A
Transfer Characteristic
02930-017
CIRCUIT INFORMATION
AD7476A/AD7477A/AD7478A
TYPICAL CONNECTION DIAGRAM
Figure 18 shows a typical connection diagram for the AD7476A/
AD7477A/AD7478A. VREF is taken internally from VDD and, as
such, VDD should be well decoupled. This provides an analog
input range of 0 V to VDD. The conversion result is output in a
16-bit word with four leading zeros followed by the MSB of the
12-bit, 10-bit, or 8-bit result. The 10-bit result from the AD7477A
is followed by two trailing zeros, and the 8-bit result from the
AD7478A is followed by four trailing zeros. Alternatively, because
the supply current required by the AD7476A/AD7477A/AD7478A
is so low, a precision reference can be used as the supply source
to the AD7476A/AD7477A/AD7478A. A REF19x voltage reference (REF195 for 5 V or REF193 for 3 V) can be used to supply
the required voltage to the ADC (see Figure 18). This configuration
is especially useful if the power supply is quite noisy, or if the
system supply voltages are at some value other than 5 V or 3 V
(for example, 15 V).
The REF19x outputs a steady voltage to the AD7476A/
AD7477A/AD7478A. If the low dropout REF193 is used, the
current it needs to supply to the AD7476A/AD7477A/ AD7478A is
typically 1.2 mA. When the ADC is converting at a rate of 1
MSPS, the REF193 needs to supply a maximum of 1.7 mA to the
AD7476A/AD7477A/AD7478A. The load regulation of the
REF193 is typically 10 ppm/mA (VS = 5 V), resulting in an error
of 17 ppm (51 µV) for the 1.7 mA drawn from it. This corresponds
to a 0.069 LSB error for the AD7476A with VDD = 3 V from the
REF193, a 0.017 LSB error for the AD7477A, and a 0.0043 LSB
error for the AD7478A.
For applications where power consumption is a concern, use the
power-down mode of the ADC and the sleep mode of the
REF19x reference to improve power performance. See the
Modes of Operation section.
3V
0.1µF
REF193
1µF
TANT
10µF
0.1µF
5V
SUPPLY
680nF
Table 7. AD7476A Typical Performance for Various Voltage
References
Reference Tied to VDD
AD780 @ 3 V
REF193
AD780 @ 2.5 V
REF192
REF43
ANALOG INPUT
Figure 19 shows an equivalent circuit of the analog input
structure of the AD7476A/AD7477A/AD7478A. The two
diodes, D1 and D2, provide ESD protection for the analog
input. Care must be taken to ensure that the analog input signal
never exceeds the supply rails by more than 300 mV. This
causes the diodes to become forward-biased and start
conducting current into the substrate. The maximum current
these diodes can conduct without causing irreversible damage
to the part is 10 mA. The Capacitor C1 in Figure 19 is typically
about 6 pF and can primarily be attributed to pin capacitance.
The Resistor R1 is a lumped component made up of the on
resistance of a switch. This resistor is typically about 100 Ω. The
Capacitor C2 is the ADC sampling capacitor and has a
capacitance of 20 pF typically.
For ac applications, removing high frequency components from
the analog input signal is recommended by use of a band-pass
filter on the relevant analog input pin. In applications where
harmonic distortion and signal-to-noise ratio are critical, drive
the analog input from a low impedance source. Large source
impedances significantly affect the ac performance of the ADC,
necessitating the use of an input buffer amplifier. The choice of
the op amp is a function of the particular application.
VDD
VIN
GND
VDD
AD7476A/
AD7477A/
AD7478A
SCLK
µC/µP
SDATA
D1
R1
VIN
CS
SERIAL
INTERFACE
02930-018
0V TO V DD
INPUT
AD7476A SNR Performance (dB)
72.65
72.35
72.5
72.2
72.6
Figure 18. REF193 as Power Supply to AD7476A/
AD7477A/AD7478A
C1
6pF
C2
20pF
D2
CONVERSION PHASE – SWITCH OPEN
TRACK PHASE – SWITCH CLOSED
Figure 19. Equivalent Analog Input Circuit
Rev. F | Page 16 of 28
02930-019
1.2mA
Table 7 provides typical performance data with various
references used as a VDD source for a 100 kHz input tone at
room temperature under the same setup conditions.
AD7476A/AD7477A/AD7478A
Table 8 provides typical performance data with various op amps
used as the input buffer for a 100 kHz input tone at room
temperature under the same setup conditions.
Table 8. AD7476A Typical Performance with Various Input
Buffers, VDD = 3 V
Op Amp in the Input Buffer
AD711
AD797
AD845
AD7476A SNR Performance (dB)
72.3
72.5
71.4
When no amplifier is used to drive the analog input, limit the
source impedance to low values. The maximum source impedance depends on the amount of total harmonic distortion (THD)
that can be tolerated. The THD increases as the source impedance
increases, degrading the performance (see Figure 13).
DIGITAL INPUTS
The digital inputs applied to the AD7476A/AD7477A/AD7478A
are not limited by the maximum ratings that limit the analog
input. Instead, the digital inputs applied can reach 7 V and are
not restricted by the VDD + 0.3 V limit as on the analog input.
For example, if operating the AD7476A/AD7477A/AD7478A
with a VDD of 3 V, use 5 V logic levels on the digital inputs.
However, note that the data output on SDATA still has 3 V logic
levels when VDD = 3 V. Another advantage of SCLK and CS not
being restricted by the VDD + 0.3 V limit is that power supply
sequencing issues are avoided. If CS or SCLK are applied before
VDD, there is no risk of latch-up as there would be on the analog
input if a signal greater than 0.3 V were applied prior to VDD.
Rev. F | Page 17 of 28
AD7476A/AD7477A/AD7478A
MODES OF OPERATION
The modes of operation for the AD7476A/AD7477A/AD7478A
are selected by controlling the (logic) state of the CS signal during
a conversion. There are two possible modes of operation: normal
and power-down. The point at which CS is pulled high after the
conversion has been initiated determines whether the AD7476A/
AD7477A/AD7478A enters power-down mode. Similarly, if
already in power-down, CS can control whether the device returns
to normal operation or remains in power-down. These modes of
operation are designed to provide flexible power management
options. These options can be chosen to optimize the power
dissipation/throughput rate ratio for different application
requirements.
NORMAL MODE
This mode is intended for the fastest throughput rate performance.
In normal mode, the user does not have to worry about any
power-up times because AD7476A/AD7477A/AD7478A
remain fully powered at all times. Figure 20 shows the general
diagram of the operation of the AD7476A/AD7477A/AD7478A
in this mode. The conversion is initiated on the falling edge of
CS as described in the Serial Interface section. To ensure that
the part remains fully powered up at all times, CS must remain
low until at least 10 SCLK falling edges have elapsed after the
falling edge of CS. If CS is brought high any time after the 10th
SCLK falling edge but before the end of the tCONVERT, the part
remains powered up, but the conversion is terminated and
SDATA goes back into three-state. For the AD7476A, 16 serial
clock cycles are required to complete the conversion and access
the complete conversion results. For the AD7477A and AD7478A,
a minimum of 14 and 12 serial clock cycles are required to complete the conversion and access the complete conversion results,
respectively. CS can idle high until the next conversion or idle
low until CS returns high sometime prior to the next conversion
(effectively idling CS low). Once a data transfer is complete
(SDATA has returned to three-state), another conversion can be
initiated after the quiet time, tQUIET, has elapsed by bringing CS
low again.
POWER-DOWN MODE
This mode is intended for use in applications where slower
throughput rates are required; either the ADC is powered down
between each conversion, or a series of conversions is performed
at a high throughput rate and the ADC is then powered down
for a relatively long duration between these bursts of several
conversions. When the AD7476A/AD7477A/AD7478A are in
power-down, all analog circuitry is powered down. To enter
power-down, the conversion process must be interrupted by
bringing CS high anywhere after the second falling edge of SCLK
and before the 10th falling edge of SCLK, as shown in Figure 22.
Once CS has been brought high in this window of SCLKs, the
part enters power-down, the conversion that was initiated by
the falling edge of CS is terminated, and SDATA goes back into
three-state. If CS is brought high before the second SCLK falling
edge, the part remains in normal mode and does not power
down. This avoids accidental power-down due to glitches on the
CS line. In order to exit this mode of operation and power up
the AD7476A/AD7477A/AD7478A again, a dummy conversion
is performed. On the falling edge of CS, the device begins to
power up and continues to power up as long as CS is held low
until after the falling edge of the 10th SCLK. The device is fully
powered up once 16 SCLKs have elapsed, and valid data results
from the next conversion, as shown in Figure 24. If CS is
brought high before the 10th falling edge of SCLK, then the
AD7476A/AD7477A/AD7478A go back into power-down. This
avoids accidental power-up due to glitches on the CS line or an
inadvertent burst of eight SCLK cycles while CS is low.
Although the device can begin to power up on the falling edge
of CS, it powers down again on the rising edge of CS as long as it
occurs before the 10th SCLK falling edge.
POWER-UP TIME
The power-up time of the AD7476A/AD7477A/AD7478A is
1 µs, meaning that with any frequency of SCLK up to 20 MHz,
one dummy cycle is always sufficient to allow the device to
power up. Once the dummy cycle is complete, the ADC is fully
powered up and the input signal is acquired properly. The quiet
time, tQUIET, must still be allowed from the point where the bus
goes back into three-state after the dummy conversion to the
next falling edge of CS. When running at a 1 MSPS throughput
rate, the AD7476A/AD7477A/AD7478A power up and acquire
a signal within 0.5 LSB in one dummy cycle, that is, 1 µs.
When powering up from the power-down mode with a dummy
cycle, as in Figure 22, the track-and-hold that was in hold mode
while the part was powered down returns to track mode after
the first SCLK edge the part receives after the falling edge of CS.
This is shown as Point A in Figure 22. Although at any SCLK
frequency, one dummy cycle is sufficient to power up the device
and acquire VIN, it does not necessarily mean that a full dummy
cycle of 16 SCLKs must always elapse to power up the device
and acquire VIN fully; 1 µs is sufficient to power up the device
and acquire the input signal. If, for example, a 5 MHz SCLK
frequency is applied to the ADC, the cycle time becomes 3.2 µs.
In one dummy cycle, 3.2 µs, the part powers up and VIN
acquires fully. However, after 1 µs with a 5 MHz SCLK, only five
SCLK cycles would have elapsed. At this stage, the ADC would
fully power up and acquire the signal. In this case, the CS can be
brought high after the 10th SCLK falling edge and brought low
again after a time, tQUIET, to initiate the conversion.
Rev. F | Page 18 of 28
AD7476A/AD7477A/AD7478A
AD7476A/AD7477A/AD7478A
CS
1
10
12
14
16
SDATA
02930-020
SCLK
VALID DATA
Figure 20. Normal Mode Operation
CS
1
10
2
12
14
16
THREE-STATE
SDATA
02930-021
SCLK
Figure 21. Entering Power-Down Mode
THE PART IS FULLY
POWERED UP WITH
VIN FULLY ACQUIRED
THE PART
BEGINS TO
POWER UP
CS
A1
10
12
14
1
16
16
SDATA
VALID DATA
INVALID DATA
02930-022
SCLK
Figure 22. Exiting Power-Down Mode
When power supplies are first applied to the AD7476A/AD7477A/
AD7478A, the ADC can power up in either the power-down or
normal modes. Because of this, it is best to allow a dummy cycle
to elapse to ensure that the part is fully powered up before
attempting a valid conversion. Likewise, if it is intended to keep
the part in the power-down mode while not in use and the user
wishes the part to power up in power-down mode, the dummy
cycle can be used to ensure that the device is in power-down by
executing a cycle such as that shown in Figure 22. Once supplies
are applied to the AD7476A/AD7477A/AD7478A, the power-up
time is the same as that when powering up from the power-down
mode. It takes approximately 1 μs to power up fully if the part
powers up in normal mode. It is not necessary to wait 1 μs before
executing a dummy cycle to ensure the desired mode of operation.
Instead, a dummy cycle can occur directly after power is
supplied to the ADC. If the first valid conversion is performed
directly after the dummy conversion, care must be taken to
ensure that an adequate acquisition time has been allowed. As
mentioned earlier, when powering up from the power-down
mode, the part returns to track upon the first SCLK edge
applied after the falling edge of CS. However, when the ADC
initially powers up after supplies are applied, the track-and-hold
is already in track. This means, assuming one has the facility to
monitor the ADC supply current, if the ADC powers up in the
desired mode of operation and thus a dummy cycle is not
required to change the mode, a dummy cycle is not required to
place the track-and-hold into track.
Rev. F | Page 19 of 28
AD7476A/AD7477A/AD7478A
POWER VS. THROUGHPUT RATE
For example, if the AD7476A/AD7477A/AD7478A operate in a
continuous sampling mode with a throughput rate of 100 kSPS
and an SCLK of 20 MHz (VDD = 5 V) and the devices are placed
in the power-down mode between conversions, the power
consumption is calculated as follows:
The power dissipation during normal operation is 17.5 mW
(VDD = 5 V). If the power-up time is one dummy cycle, that is,
1 μs, and the remaining conversion time is another cycle, that is,
1 μs, then the AD7476A/AD7477A/AD7478A dissipate 17.5 mW
for 2 μs during each conversion cycle.
If VDD = 3 V, SCLK = 20 MHz, and the devices are again in
power-down mode between conversions, then the power
dissipation during normal operation is 5.1 mW. Thus, the
AD7576A/AD7477A/AD8478A dissipate 5.1 mW for 2 μs
during each conversion cycle. With a throughput rate of
100 kSPS, the average power dissipated during each cycle is
(2/10) × (5.1 mW) = 1.02 mW.
Figure 23 shows the power vs. the throughput rate when using
the power-down mode between conversions with both 5 V and
3 V supplies. The power-down mode is intended for use with
throughput rates of approximately 333 kSPS or less, because at
higher sampling rates, the power-down mode produces no
power savings.
If the throughput rate is 100 kSPS, the cycle time is 10 μs, then
the average power dissipated during each cycle is (2/10) ×
(17.5 mW) = 3.5 mW.
100
VDD = 5V, SCLK = 20MHz
10
POWER (mW)
By using the power-down mode on the AD7476A/AD7477A/
AD7478A when not converting, the average power consumption of the ADC decreases at lower throughput rates. Figure 23
shows that as the throughput rate is reduced, the device remains
in its power-down state longer and the average power consumption
over time drops accordingly.
1
VDD = 3V, SCLK = 20MHz
02930-023
0.1
0.01
0
50
100
150
200
250
THROUGHPUT (kSPS)
Figure 23. Power vs. Throughput
Rev. F | Page 20 of 28
300
350
AD7476A/AD7477A/AD7478A
SERIAL INTERFACE
falling edge, as shown in Figure 24. Sixteen serial clock cycles
are required to perform the conversion process and to access
data from the AD7476A.
Figure 24, Figure 25, and Figure 26 show the detailed timing
diagrams for serial interfacing to the AD7476A, AD7477A, and
AD7478A, respectively. The serial clock provides the conversion
clock and also controls the transfer of information from the
AD7476A/AD7477A/AD7478A during conversion.
For the AD7477A, the conversion requires 14 SCLK cycles to
complete. Once 13 SCLK falling edges have elapsed, the trackand-hold goes back into track on the next rising edge as shown
at Point B in Figure 25. If the rising edge of CS occurs before
14 SCLKs have elapsed, the conversion is terminated and the
SDATA line goes back into three-state. If 16 SCLKs are
considered in the cycle, SDATA returns to three-state on the
16th SCLK falling edge, as shown in Figure 25.
The CS signal initiates the data transfer and conversion process.
The falling edge of CS puts the track-and-hold into hold mode
and takes the bus out of three-state; the analog input is sampled
at this point. Also, the conversion is initiated at this point.
For the AD7476A, the conversion requires 16 SCLK cycles to
complete. Once 13 SCLK falling edges have elapsed, the trackand-hold goes back into track on the next SCLK rising edge, as
shown in Figure 24 at Point B. On the 16th SCLK falling edge,
the SDATA line goes back into three-state. If the rising edge of
CS occurs before 16 SCLKs have elapsed, the conversion is
terminated and the SDATA line goes back into three-state;
otherwise, SDATA returns to three-state on the 16th SCLK
For the AD7478A, the conversion requires 12 SCLK cycles to
complete. The track-and-hold goes back into track on the rising
edge after the 11th falling edge, as shown in Figure 26 at Point B. If
the rising edge of CS occurs before 12 SCLKs have elapsed, the
conversion is terminated and the SDATA line goes back into threestate. If 16 SCLKs are considered in the cycle, SDATA returns to
three-state on the 16th SCLK falling edge, as shown in Figure 26.
t1
CS
tCONVERT
t6
1
SCLK
3
2
4
B
13
5
14
15
16
t5
t3
SDATA
Z
THREESTATE
t4
ZERO
ZERO
t8
t7
ZERO
DB11
tQUIET
DB10
DB2
DB1
DB0
THREE-STATE
02930-024
t2
4 LEADING ZEROS
1/THROUGHPUT
Figure 24. AD7476A Serial Interface Timing Diagram
t1
CS
tCONVERT
t2
t6
2
3
t3
Z
SDATA
THREE-STATE
B
5
4
ZERO
ZERO
14
DB9
15
t5
t7
t4
ZERO
13
ZERO
DB0
DB8
16
t8
tQUIET
ZERO
THREE-STATE
2 TRAILING ZEROS
4 LEADING ZEROS
02930-025
1
SCLK
1/ THROUGHPUT
Figure 25. AD7477A Serial Interface Timing Diagram
t1
CS
tCONVERT
B
t6
1
11
4
3
2
13
12
15
14
16
t8
t5
t4
t3
SDATA
THREE-STATE
Z
ZERO
ZERO
ZERO
4 LEADING ZEROS
DB7
t7
ZERO
ZERO
ZERO
ZERO
4 TRAILING ZEROS
1/ THROUGHPUT
Figure 26. AD7478A Serial Interface Timing Diagram
Rev. F | Page 21 of 28
tQUIET
THREE-STATE
02930-026
t2
SCLK
AD7476A/AD7477A/AD7478A
CS going low clocks out the first leading zero to be read in by
the microcontroller or DSP. The remaining data is then clocked
out by subsequent SCLK falling edges beginning with the
second leading zero. Thus, the first falling clock edge on the
serial clock has the first leading zero provided and also clocks
out the second leading zero. For the AD7476A, the final bit in
the data transfer is valid on the 16th falling edge, having been
clocked out on the previous (15th) falling edge.
AD7478A IN A 12 SCLK CYCLE SERIAL INTERFACE
For the AD7478A, if CS is brought high in the 12th rising edge
after four leading zeros and eight bits of the conversion have
been provided, the part can achieve a 1.2 MSPS throughput
rate. For the AD7478A, the track-and-hold goes back into track
in the 11th rising edge. In this case, a fSCLK = 20 MHz and a
throughput of 1.2 MSPS give a cycle time of
t2 + 10.5(1/fSCLK)+ tACQ = 833 ns
In applications with a slower SCLK, it is possible to read in data
on each SCLK rising edge. In this case, the first falling edge of
SCLK clocks out the second leading zero, which can be read in
the first rising edge. However, the first leading zero that was
clocked out when CS went low will be missed, unless it was not
read in the first falling edge. The 15th falling edge of SCLK clocks
out the last bit and it can be read in the 15th rising SCLK edge.
With t2 = 10 ns min, this leaves tACQ to be 298 ns. This 298 ns
satisfies the requirement of 225 ns for tACQ.
From Figure 27, tACQ is comprised of
0.5 (1/fSCLK) + t8 + tQUIET
where t8 = 36 ns maximum.
If CS goes low just after one SCLK falling edge has elapsed, CS
clocks out the first leading zero as it did before, and it can be
read in the SCLK rising edge. The next SCLK falling edge clocks
out the second leading zero, and it can be read in the following
rising edge.
This allows a value of 237 ns for tQUIET, satisfying the minimum
requirement of 50 ns.
t1
CS
tCONVERT
B
1
2
3
4
11
5
12
t8
10.5(1/fSCLK)
SDATA
THREE-STATE
Z
ZERO
ZERO
ZERO
4 LEADING ZEROS
DB7
tQUIET
tACQ
DB6
DB0
THREE-STATE
1/THROUGHPUT
Figure 27. AD7478A in a 12 SCLK Cycle Serial Interface
Rev. F | Page 22 of 28
02930-027
SCLK
t2
AD7476A/AD7477A/AD7478A
MICROPROCESSOR INTERFACING
The connection diagram is shown in Figure 28. For signal
processing applications, it is imperative that the frame
synchronization signal from the TMS320C541 provide
equidistant sampling.
AD7476A/
AD7477A/
AD7478A1
AD7476A/AD7477A/AD7478A TO TMS320C541
INTERFACE
The serial interface on the TMS320C541 uses a continuous
serial clock and frame synchronization signals to synchronize
the data transfer operations with peripheral devices, such as
the AD7476A/AD7477A/AD7478A. The CS input allows easy
interfacing between the TMS320C541 and the AD7476A/
AD7477A/AD7478A without any glue logic required. The serial
port of the TMS320C541 is set up to operate in burst mode
(FSM = 1 in the serial port control register, SPC) with Internal
Serial Clock CLKX (MCM = 1 in the SPC register) and internal
frame signal (TXM = 1 in the SPC register), so both pins are
configured as outputs. For the AD7476A, set the word length to
16 bits (FO = 0 in the SPC register). This DSP only allows
frames with a word length of 16 bits or 8 bits. Therefore, in the
case of the AD7477A and AD7478A where 14 bits and 12 bits
are required, the FO bit is set up to 16 bits. This means that to
obtain the conversion result, 16 SCLKs are needed. In both
situations, the remaining SCLKs clock out trailing zeros. For the
AD7477A, two trailing zeros are clocked out in the last two clock
cycles; for the AD7478A, four trailing zeros are clocked out.
To summarize, the values in the SPC register are
FO = 0
FSM = 1
MCM = 1
TXM = 1
The format bit, FO, can be set to 1 to set the word length to
eight bits in order to implement the power-down mode on the
AD7476A/AD7477A/AD7478A.
TMS320C5411
SCLK
CLKX
CLKR
SDATA
CS
DR
FSX
FSR
1ADDITIONAL PINS OMITTED FOR CLARITY.
02930-028
The serial interface on the AD7476A/AD7477A/AD7478A
allows the part to be directly connected to a range of different
microprocessors. This section explains how to interface the
AD7476A/AD7477A/AD7478A with some of the more
common microcontroller and DSP serial interface protocols.
Figure 28. Interfacing to the TMS320C541
AD7476A/AD7477A/AD7478A TO ADSP-218x
INTERFACE
The ADSP-218x family of DSPs are interfaced directly to the
AD7476A/AD7477A/AD7478A without any glue logic
required. Set up the SPORT control register as follows:
TFSW = RFSW = 1, alternate framing
INVRFS = INVTFS = 1, active low frame signal
DTYPE = 00, right justify data
ISCLK = 1, internal serial clock
TFSR = RFSR = 1, frame every word
IRFS = 0, sets up RFS as an input
ITFS = 1, sets up TFS as an output
SLEN = 1111, 16 bits for the AD7476A
SLEN = 1101, 14 bits for the AD7477A
SLEN = 1011, 12 bits for the AD7478A
Rev. F | Page 23 of 28
AD7476A/AD7477A/AD7478A
AD7476A/
AD7477A/
AD7478A1
ADSP-218x1
SCLK
SDATA
CS
SCLK
DR
RFS
1ADDITIONAL
PINS OMITTED FOR CLARITY.
02930-029
TFS
Figure 29. Interfacing to the ADSP-218x
The timer registers, for example, are loaded with a value that
provides an interrupt at the required sample interval. When an
interrupt is received, a value is transmitted with TFS/DT (ADC
control word). The TFS controls the RFS and, thus, the reading
of data. The frequency of the serial clock is set in the SCLKDIV
register. When the instruction to transmit with TFS is given,
that is, TX0 = AX0, the state of the SCLK is checked. The DSP
waits until the SCLK has gone high, low, and high before
transmission starts. If the timer and SCLK values are chosen
such that the instruction to transmit occurs on or near the
rising edge of SCLK, the data can be transmitted or it can wait
until the next clock edge. For example, the ADSP-2111 has a
master clock frequency of 16 MHz. If the SCLKDIV register is
loaded with the Value 3, an SCLK of 2 MHz is obtained and
eight master clock periods will elapse for every one SCLK
period. If the timer registers are loaded with the Value 803,
100.5 SCLKs occur between interrupts and, subsequently,
between transmit instructions. This situation results in
nonequidistant sampling as the transmit instruction is
occurring on an SCLK edge. If the number of SCLKs between
interrupts is a whole integer figure of N, equidistant sampling is
implemented by the DSP.
AD7476A/AD7477A/AD7478A TO DSP563xx
INTERFACE
The connection diagram in Figure 30 shows how the
AD7476A/AD7477A/AD7478A can be connected to the SSI
(synchronous serial interface) of the DSP563xx family of DSPs
from Motorola. The SSI is operated in synchronous and normal
mode (SYN 1 = and MOD = 0 in Control Register B, CRB) with
internally generated word length frame sync for both Tx and Rx
(Bit FSL1 = 0 and Bit FSL0 = 0 in CRB). Set the word length in
Control Register A (CRA) to 16 by setting Bit WL2 = 0, Bit
WL1 = 1, and Bit WL0 = 0 for the AD7476A. The word length
for the AD7478A can be set to 12 bits (WL2 = 0, WL1 = 0, and
WL0 = 1). This DSP does not offer the option for a 14-bit word
length, so the AD7477A word length is set up to 16 bits, the
same as the AD7476A. For the AD7477A, the conversion process
uses 16 SCLK cycles, with the last two clock periods clocking out
two trailing zeros to fill the 16-bit word.
To implement the power-down mode on the AD7476A/AD7477A/
AD7478A, the word length can be changed to eight bits by setting
Bit WL2 = 0, Bit WL1 = 0, and Bit WL0 = 0 in CRA. The FSP
bit in the CRB register can be set to 1, meaning the frame goes
low and a conversion starts. Likewise, by means of the Bit SCD2,
Bit SCKD, and Bit SHFD in the CRB register, it establishes that
Pin SC2 (the frame sync signal) and Pin SCK in the serial port
are configured as outputs and the MSB is shifted first.
In summary:
MOD = 0
SYN = 1
WL2, WL1, and WL0 depend on the word length
FSL1 = 0 and FSL0 = 0
FSP = 1, negative frame sync
SCD2 = 1
SCKD = 1
SHFD = 0
Note that for signal processing applications, it is imperative that
the frame synchronization signal from the DSP563xx provide
equidistant sampling.
AD7476A/
AD7477A
AD7478A1
DSP563xx1
SCLK
SCK
SDATA
SRD
CS
SC2
1ADDITIONAL
PINS OMITTED FOR CLARITY.
Figure 30. Interfacing to the DSP563xx
Rev. F | Page 24 of 28
02930-030
To implement the power-down mode, set SLEN to 0111 to issue
an 8-bit SCLK burst. The connection diagram is shown in
Figure 29. The ADSP-218x has the TFS and RFS of the SPORT
tied together, with TFS set as an output and RFS set as an input.
The DSP operates in alternate framing mode, and the SPORT
control register is set up as described. The frame synchronization
signal generated on the TFS is tied to CS, and, as with all signal
processing applications, equidistant sampling is necessary.
However, in this example, the timer interrupt is used to control
the sampling rate of the ADC and, under certain conditions,
equidistant sampling may not be achieved.
AD7476A/AD7477A/AD7478A
APPLICATION HINTS
Design the printed circuit board that houses the AD7476A/
AD7477A/AD7478A such that the analog and digital sections
are separated and confined to certain areas of the board. This
facilitates the use of ground planes that can be separated easily.
A minimum etch technique is generally best for ground planes
because it gives the best shielding. Join digital and analog
ground planes at only one place. If the AD7476A/AD7477A/
AD7478A is in a system where multiple devices require an
AGND to DGND connection, make the connection at one
point only, a star ground point that is established as close as
possible to the AD7476A/AD7477A/AD7478A.
Avoid running digital lines under the device as these couple
noise onto the die. Allow the analog ground plane to run under
the AD7476A/AD7477A/AD7478A in order to avoid noise
coupling. Use as large a trace as possible on the power supply
lines to the AD7476A/AD7477A/AD7478A to provide low
impedance paths and reduce the effects of glitches on the power
supply line. Shield fast switching signals like clocks with digital
grounds to avoid radiating noise to other sections of the board,
and never run clock signals near the analog inputs. Avoid crossover
of digital and analog signals. Run traces on opposite sides of the
board at right angles to each other. This reduces the effects of
feedthrough through the board. A microstrip technique is by far
the best but is not always possible with a double-sided board. In
this technique, the component side of the board is dedicated to
ground planes while signals are placed on the solder side.
Similarly, for the SC70 package, locate the decoupling capacitor
as close as possible to the VDD and the GND pins. Because of its
pinout, that is, VDD being next to GND, the decoupling capacitor
can be placed extremely close to the IC. The decoupling capacitor
can be placed on the underside of the PCB directly under the
VDD and GND pins, but the best performance is achieved with
the decoupling capacitor on the same side as the IC.
Figure 32. Recommended Supply Decoupling Scheme for the
AD7476A/AD7477A/AD7478A MSOP Package
EVALUATING THE AD7476A/AD7477A
PERFORMANCE
The evaluation board package includes a fully assembled and
tested evaluation board, documentation, and software for
controlling the board from the PC via the EVAL-BOARD
CONTROLLER. The EVAL-BOARD CONTROLLER can be
used in conjunction with the AD7476ACB/AD7477ACB
evaluation board, as well as many other Analog Devices
evaluation boards ending in the CB designator, to
demonstrate/evaluate the ac and dc performance of the
AD7476A/AD7477A. The software allows the user to perform
ac (fast Fourier transform) and dc (histogram of codes) tests on
the AD7476A/AD7477A. See the evaluation board application
note for more information.
02930-032
Good decoupling is also very important. Decouple the supply
with, for instance, a 680 nF 0805 capacitor to GND. When using
the SC70 package in applications where the size of the components
is of concern, a 220 nF 0603 capacitor, for example, can be used
instead. However, in that case, the decoupling may not be as
effective, resulting in an approximate SINAD degradation of
0.3 dB. To achieve the best performance from these decoupling
components, the user should endeavor to keep the distance
between the decoupling capacitor and the VDD and GND pins to
a minimum with short track lengths connecting the respective
pins. Figure 31 and Figure 32 and show the recommended
positions of the decoupling capacitor for the SC70 and MSOP
packages, respectively.
As can be seen in Figure 32, for the MSOP package, the
decoupling capacitor has been placed as close as possible to the
IC with short track lengths to VDD and GND pins. The
decoupling capacitor can also be placed on the underside of the
PCB directly underneath the IC, between the VDD and GND
pins attached by vias. This method is not recommended on
PCBs above a standard 1.6 mm thickness. The best performance
is realized with the decoupling capacitor on the top of the PCB
next to the IC.
02930-031
GROUNDING AND LAYOUT
Figure 31. Recommended Supply Decoupling Scheme for the SC70 Package
Rev. F | Page 25 of 28
AD7476A/AD7477A/AD7478A
OUTLINE DIMENSIONS
2.20
2.00
1.80
6
5
4
1
2
3
8
3.20
3.00
2.80
1
5
5.15
4.90
4.65
4
PIN 1
IDENTIFIER
0.65 BSC
1.30 BSC
0.65 BSC
1.10
0.80
0.30
0.15
SEATING
PLANE
0.40
0.10
0.22
0.08
0.95
0.85
0.75
0.46
0.36
0.26
COMPLIANT TO JEDEC STANDARDS MO-203-AB
15° MAX
1.10 MAX
0.15
0.05
COPLANARITY
0.10
Figure 33. 6-Lead Thin Shrink Small Outline Transistor Package [SC70]
(KS-6)
Dimensions shown in millimeters
0.40
0.25
6°
0°
0.80
0.55
0.40
0.23
0.09
10-07-2009-B
1.00
0.90
0.70
0.10 MAX
COPLANARITY
0.10
2.40
2.10
1.80
072809-A
1.35
1.25
1.15
3.20
3.00
2.80
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 34. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
ORDERING GUIDE
Model1, 2, 3, 4
AD7476AAKSZ-500RL7
AD7476AAKSZ-REEL
AD7476AAKSZ-REEL7
AD7476ABKSZ-500RL7
AD7476ABKSZ-REEL
AD7476ABKSZ-REEL7
AD7476ABRM
AD7476ABRM-REEL
AD7476ABRM-REEL7
AD7476ABRMZ
AD7476ABRMZ-REEL
AD7476ABRMZ-REEL7
AD7476AWYRMZ
AD7476AWYRMZ-RL7
AD7476AYKSZ-500RL7
AD7476AYKSZ-REEL7
AD7476AYRMZ
AD7476AYRMZ-REEL7
AD7477AAKSZ-500RL7
AD7477AAKSZ-REEL
AD7477AARM-REEL
AD7477AARMZ
AD7477AARMZ-REEL
AD7477AARMZ-REEL7
AD7477AWARMZ
AD7477AWARMZ-RL
AD7478AAKSZ-500RL7
AD7478AAKSZ-REEL
AD7478AAKSZ-REEL7
AD7478AARM
AD7478AARMZ
Temperature Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Linearity Error (LSB)5
±0.75 typical
±0.75 typical
±0.75 typical
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±1.5 maximum
±0.5 maximum
±0.5 maximum
±0.5 maximum
±0.5 maximum
±0.5 maximum
±0.5 maximum
±0.5 maximum
±0.5 maximum
±0.3 maximum
±0.3 maximum
±0.3 maximum
±0.3 maximum
±0.3 maximum
Rev. F | Page 26 of 28
Package Description
6-Lead SC70
6-Lead SC70
6-Lead SC70
6-Lead SC70
6-Lead SC70
6-Lead SC70
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
6-Lead SC70
6-Lead SC70
8-Lead MSOP
8-Lead MSOP
6-Lead SC70
6-Lead SC70
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
6-Lead SC70
6-Lead SC70
6-Lead SC70
8-Lead MSOP
8-Lead MSOP
Package Option6
KS-6
KS-6
KS-6
KS-6
KS-6
KS-6
RM-8
RM-8
RM-8
RM-8
RM-8
RM-8
RM-8
RM-8
KS-6
KS-6
RM-8
RM-8
KS-6
KS-6
RM-8
RM-8
RM-8
RM-8
RM-8
RM-8
KS-6
KS-6
KS-6
RM-8
RM-8
Branding
C3V
C3V
C3V
C3W
C3W
C3W
CEY
CEY
CEY
C3W
C3W
C3W
C45
C45
C45
C45
C45
C45
C3X
C3X
CFZ
C3X
C3X
C3X
C3X
C3X
C48
C48
C48
CJZ
C48
AD7476A/AD7477A/AD7478A
Model1, 2, 3, 4
AD7478AARMZ-REEL
AD7478AARMZ-REEL7
AD7478AWARMZ
AD7478AWARMZ-RL
EVAL-AD7476ACBZ
EVAL-CONTROL BRD2
Temperature Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Linearity Error (LSB)5
±0.3 maximum
±0.3 maximum
±0.3 maximum
±0.3 maximum
Package Description
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
8-Lead MSOP
Evaluation Board
Evaluation Control
Package Option6
RM-8
RM-8
RM-8
RM-8
Branding
C48
C48
C48
C48
Z = RoHS Compliant Part.
W = Qualified for Automotive Applications.
EVAL-AD7476ACBZ can be used as a standalone evaluation board or in conjunction with the EVAL-CONTROL BOARD for evaluation/demonstration purposes.
4
EVAL-CONTROL BRD2 is a complete unit, allowing a PC to control and communicate with all Analog Devices evaluation boards ending in the CB designator. To order a
complete evaluation kit, you will need to order the particular ADC evaluation board, for example, EVAL-AD7476ACB, the EVAL-CONTROLBRD2, and a 12 V ac
transformer. See relevant evaluation board application note for more information.
5
Linearity error here refers to integral nonlinearity.
6
KS = SC70; RM = MSOP.
1
2
3
AUTOMOTIVE PRODUCTS
The AD7476AWYRMZ, AD7476AWYRMZ-RL7, AD7477AWARMZ, AD7477AWARMZ-RL, AD7478AWARMZ, and
AD7478AWARMZ-RL models are available with controlled manufacturing to support the quality and reliability requirements of
automotive applications. Note that these automotive models may have specifications that differ from the commercial models; therefore,
designers should review the Specifications section of this data sheet carefully. Only the automotive grade products shown are available for
use in automotive applications. Contact your local Analog Devices account representative for specific product ordering information and
to obtain the specific Automotive Reliability reports for these models.
Rev. F | Page 27 of 28
AD7476A/AD7477A/AD7478A
NOTES
©2002–2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D02930-0-1/11(F)
Rev. F | Page 28 of 28