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Data Sheet
FEATURES
Fast throughput rate: 200 kSPS
Specified for AV
DD
of 2.7 V to 5.25 V
Low power
3.6 mW maximum at 200 kSPS with 3 V supply
7.5 mW maximum at 200 kSPS with 5 V supply
8 (single-ended) inputs with sequencer
Wide input bandwidth
70 dB minimum SINAD at 50 kHz input frequency
Flexible power/serial clock speed management
No pipeline delays
High speed serial interface SPI-, QSPI™-, MICROWIRE™-,
DSP-compatible
Shutdown mode: 0.5 μA maximum
20-lead TSSOP
Qualified for automotive applications
8-Channel, 200 kSPS, 12-Bit ADC
with Sequencer in 20-Lead TSSOP
AD7927
FUNCTIONAL BLOCK DIAGRAM
AV
DD
REF
IN
V
IN
0
T/H
INPUT
MUX
12-BIT
SUCCESSIVE
APPROXIMATION
ADC
V
IN
7
SEQUENCER
CONTROL LOGIC
SCLK
DOUT
DIN
CS
03088-001
AD7927
AGND
V
DRIVE
GENERAL DESCRIPTION
The AD7927 is a 12-bit, high speed, low power, 8-channel,
successive approximation ADC. The part operates from a
single 2.7 V to 5.25 V power supply and features throughput
rates up to 200 kSPS. The part contains a low noise, wide
bandwidth track-and-hold amplifier that can handle input
frequencies in excess of 8 MHz.
The conversion process and data acquisition are controlled using
CS and the serial clock signal, allowing the device to easily 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 part.
The AD7927 uses advanced design techniques to achieve
very low power dissipation at maximum throughput rates. At
maximum throughput rates, the AD7927 consumes 1.2 mA
maximum with 3 V supplies; with 5 V supplies, the current
consumption is 1.5 mA maximum.
Through the configuration of the control register, the analog
input range for the part can be selected as 0 V to REF
IN
or 0 V
to 2 × REF
IN
, with either straight binary or twos complement
output coding. The AD7927 features eight single-ended analog
inputs with a channel sequencer to allow a preprogrammed
selection of channels to be converted sequentially.
The conversion time for the AD7927 is determined by the
SCLK frequency, as this is also used as the master clock to
control the conversion. The conversion time may be as short
as 800 ns with a 20 MHz SCLK.
Rev. D
Document Feedback
Figure 1.
PRODUCT HIGHLIGHTS
1.
High Throughput with Low Power Consumption.
The AD7927 offers up to 200 kSPS throughput rates. At the
maximum throughput rate with 3 V supplies, the AD7927
dissipates 3.6 mW of power maximum.
Eight Single-Ended Inputs with a Channel Sequencer.
A consecutive sequence of channels can be selected on
which the ADC cycles and converts.
Single-Supply Operation with V
DRIVE
Function.
The AD7927 operates from a single 2.7 V to 5.25 V supply.
The V
DRIVE
function allows the serial interface to connect
directly to either 3 V or 5 V processor systems independent
of AV
DD
.
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. The part also features various
shutdown modes to maximize power efficiency at lower
throughput rates. Current consumption is 0.5 μA maxi-
mum when in full shutdown.
No Pipeline Delay.
The part features a standard successive approximation ADC
with a CS input pin, which allows for accurate control of
each sampling instant.
2.
3.
4.
5.
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 ©2003–2013 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
AD7927
TABLE OF CONTENTS
Features .............................................................................................. 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Timing Specifications .................................................................. 5
Absolute Maximum Ratings............................................................ 6
ESD Caution .................................................................................. 6
Pin Configuration and Function Descriptions ............................. 7
Terminology ...................................................................................... 8
Typical Performance Characteristics ........................................... 10
Control Register .............................................................................. 12
Sequencer Operation...................................................................... 13
Shadow Register .............................................................................. 14
Circuit Information .................................................................... 15
Converter Operation .................................................................. 15
Analog Input ............................................................................... 15
ADC Transfer Function ............................................................. 16
Handling Bipolar Input Signals ................................................ 16
Typical Connection Diagram ........................................................ 17
Data Sheet
Analog Input Selection .............................................................. 17
Digital Inputs .............................................................................. 17
V
DRIVE
............................................................................................ 18
The Reference ............................................................................. 18
Modes of Operation ....................................................................... 19
Normal Mode (PM1 = PM0 = 1) ............................................. 19
Full Shutdown (PM1 = 1, PM0 = 0) ........................................ 19
Auto Shutdown (PM1 = 0, PM0 = 1)....................................... 20
Powering Up the AD7927 ......................................................... 21
Power vs. Throughput Rate ....................................................... 21
Serial Interface ................................................................................ 22
Writing Between Conversions .................................................. 22
Microprocessor Interfacing ........................................................... 24
AD7927 to TMS320C541 .......................................................... 24
AD7927 to ADSP-21xx .............................................................. 24
AD7927 to DSP563xx ................................................................ 25
Application Hints ........................................................................... 26
Grounding and Layout .............................................................. 26
Outline Dimensions ....................................................................... 27
Ordering Guide .......................................................................... 27
Automotive Products ................................................................. 27
REVISION HISTORY
6/13—Rev. C to Rev. D
Deleted Evaluating the AD7927 Performance Section .............. 26
Changes to Ordering Guide .......................................................... 27
12/11—Rev. B to Rev. C
Changes to Features Section............................................................ 1
Changes to Table 1 ............................................................................ 3
Changes to Table 3 ............................................................................ 6
Changes to Ordering Guide, Added Automotive Products
Section .............................................................................................. 27
12/08—Rev. A to Rev. B
Changes to ESD Parameter, Table 3 ................................................6
Changes to Ordering Guide .......................................................... 27
1/07—Rev. 0 to Rev. A
Updated Format .................................................................. Universal
Updated Layout .................................................................................8
Updated Layout .............................................................................. 10
Changes to Figure 12 Caption ...................................................... 14
Changes to Figure 13 Caption ...................................................... 15
Changes to Ordering Guide .......................................................... 27
1/03—Revision 0: Initial Version
Rev. D | Page 2 of 28
Data Sheet
SPECIFICATIONS
AV
DD
= V
DRIVE
= 2.7 V to 5.25 V, REF
IN
= 2.5 V, f
SCLK
= 20 MHz; T
A
= T
MIN
to T
MAX
, unless otherwise noted.
Table 1.
Parameter
DYNAMIC PERFORMANCE
Signal-to-(Noise + Distortion) (SINAD)
2
B Version
1
70
69.5
69
70
69.5
−77
−73
−78
−76
−90
−90
10
50
−82
8.2
1.6
12
±1
−0.9/+1.5
±8
±0.5
±1.5
±0.5
±1.5
±0.5
±8
±0.5
±1
±0.5
0 to REF
IN
0 to 2 × REF
IN
±1
20
2.5
±1
36
0.7 × V
DRIVE
0.3 × V
DRIVE
±1
10
Unit
dB min
dB min
dB min
dB min
dB min
dB max
dB max
dB max
dB max
dB typ
dB typ
ns typ
ps typ
dB typ
MHz typ
MHz typ
Bits
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
V
V
μA max
pF typ
V
μA max
kΩ typ
V min
V max
μA max
pF max
Test Conditions/Comments
f
IN
= 50 kHz sine wave, f
SCLK
= 20 MHz
@ 5 V, B models
@ 5 V, W models
@ 3 V Typically 70 dB
B models
W models
@ 5 V Typically −84 dB
@ 3 V Typically −77 dB
@ 5 V Typically −86 dB
@ 3 V Typically −80 dB
f
A
= 40.1 kHz, f
B
= 41.5 kHz
AD7927
Signal-to-Noise Ratio (SNR)
2
Total Harmonic Distortion (THD)
2
Peak Harmonic or Spurious Noise
(SFDR)
2
Intermodulation Distortion (IMD)
2
Second-Order Terms
Third-Order Terms
Aperture Delay
Aperture Jitter
Channel-to-Channel Isolation
2
Full Power Bandwidth
DC ACCURACY
2
Resolution
Integral Nonlinearity
Differential Nonlinearity
0 V to REF
IN
Input Range
Offset Error
Offset Error Match
Gain Error
Gain Error Match
0 V to 2 × REF
IN
Input Range
Positive Gain Error
Positive Gain Error Match
Zero Code Error
Zero Code Error Match
Negative Gain Error
Negative Gain Error Match
ANALOG INPUT
Input Voltage Ranges
DC Leakage Current
Input Capacitance
REFERENCE INPUT
REF
IN
Input Voltage
DC Leakage Current
REF
IN
Input Impedance
LOGIC INPUTS
Input High Voltage, V
INH
Input Low Voltage, V
INL
Input Current, I
IN
Input Capacitance, C
IN3
f
IN
= 400 kHz
@ 3 dB
@ 0.1 dB
Guaranteed no missed codes to 12 bits
Straight binary output coding
Typically ±0.5 LSB
−REF
IN
to +REF
IN
biased about REF
IN
with
Twos complement output coding
Typically ±0.8 LSB
RANGE bit set to 1
RANGE bit set to 0, AV
DD
/V
DRIVE
= 4.75 V to 5.25 V
f
SAMPLE
= 200 kSPS
±1% specified performance
Typically 10 nA, V
IN
= 0 V or V
DRIVE
Rev. D | Page 3 of 28
AD7927
Parameter
LOGIC OUTPUTS
Output High Voltage, V
OH
Output Low Voltage, V
OL
Floating-State Leakage Current
Floating-State Output Capacitance
3
Output Coding
Straight (Natural) Binary
Twos Complement
CONVERSION RATE
Conversion Time
Track-and-Hold Acquisition Time
Throughput Rate
POWER REQUIREMENTS
AV
DD
V
DRIVE
I
DD4
During Conversion
Normal Mode (Static)
Normal Mode (Operational) f
SAMPLE
= 200 kSPS
Using Auto Shutdown Mode f
SAMPLE
= 200 kSPS
Auto Shutdown (Static)
Full Shutdown Mode
Power Dissipation
4
Normal Mode (Operational)
Auto Shutdown (Static)
Full Shutdown Mode
B Version
1
V
DRIVE
− 0.2
0.4
±1
10
Unit
V min
V max
μA max
pF max
Test Conditions/Comments
Data Sheet
I
SOURCE
= 200 μA, AV
DD
= 2.7 V to 5.25 V
I
SINK
= 200 μA
Coding bit set to 1
Coding bit set to 0
800
300
300
200
2.7/5.25
2.7/5.25
2.7
2
600
1.5
1.2
900
650
0.5
0.5
7.5
3.6
2.5
1.5
2.5
1.5
ns max
ns max
ns max
kSPS max
V min/max
V min/max
mA max
mA max
μA typ
mA max
mA max
μA typ
μA typ
μA max
μA max
mW max
mW max
μW max
μW max
μW max
μW max
Digital inputs = 0 V or V
DRIVE
AV
DD
= 4.75 V to 5.25 V, f
SCLK
= 20 MHz
AV
DD
= 2.7 V to 3.6 V, f
SCLK
= 20 MHz
AV
DD
= 2.7 V to 5.25 V, SCLK on or off
AV
DD
= 4.75 V to 5.25 V, f
SCLK
= 20 MHz
AV
DD
= 2.7 V to 3.6 V, f
SCLK
= 20 MHz
AV
DD
= 4.75 V to 5.25 V, f
SCLK
= 20 MHz
AV
DD
= 2.7 V to 3.6 V, f
SCLK
= 20 MHz
SCLK on or off (20 nA typ)
SCLK on or off (20 nA typ)
AV
DD
= 5 V, f
SCLK
= 20 MHz
AV
DD
= 3 V, f
SCLK
= 20 MHz
AV
DD
= 5 V
AV
DD
= 3 V
AV
DD
= 5 V
AV
DD
= 3 V
16 SCLK cycles with SCLK at 20 MHz
Sine wave input
Full-scale step input
See Serial Interface section
1
2
Temperature ranges as follows: B Version: −40°C to +85°C; W Version: −40°C to +125°C.
See Terminology section.
3
Sample tested @ 25°C to ensure compliance.
4
See Power vs. Throughput Rate section.
Rev. D | Page 4 of 28
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