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AD7922ARMZ

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32
2-Channel, 2.35 V to 5.25 V,
1 MSPS, 10-/12-Bit ADCs
AD7912/AD7922
Rev. 0
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: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
FEATURES
Fast throughput rate: 1 MSPS
Specified for V
DD
of 2.35 V to 5.25 V
Low power:
4.8 mW typ at 1 MSPS with 3 V supplies
15.5mW typ at 1 MSPS with 5 V supplies
Wide input bandwidth:
71 dB minimum 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
Daisy-chain mode
8-lead TSOT package
8-lead MSOP package
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 AD7912/AD7922
1
are 10-bit and 12-bit, high speed, low
power, 2-channel successive approximation ADCs, respectively.
The parts operate from a single 2.35 V to 5.25 V power supply
and feature throughput rates of up to 1 MSPS. The parts contain
a low noise, wide bandwidth track-and-hold amplifier, which
can handle input frequencies in excess of 6 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 conversion rate is
determined by the SCLK signal. The input signal is sampled on
the falling edge of
CS
and the conversion is also initiated at this
point. The channel to be converted is selected through the DIN
pin, and the mode of operation is controlled by
CS
. The serial
data stream from the DOUT pin has a channel identifier bit and
mode identifier bit, which provide information about the
converted channel and the current mode of operation.
FUNCTIONAL BLOCK DIAGRAM
04351-0-001
T/H
CONTROL LOGIC
10-/12-BIT
SUCCESSIVE
APPROXIMATION
ADC
GND
V
DD
AD7912/AD7922
V
IN0
V
IN1
SCLK
DOUT
CS
DIN
MUX
Figure 1.
Several AD7912/AD7922 can be connected together in a daisy
chain. The AD7912/AD7922 feature a daisy-chain mode that
allows the user to read the conversion results from the ADCs
contained in the chain. The AD7912/AD7922 use advanced
design techniques to achieve very low power dissipation at high
throughput rates. The reference for the part is taken internally
from V
DD
, thereby allowing the widest dynamic input range to
the ADC.
PRODUCT HIGHLIGHTS
1. 2-channel, 1 MSPS, 10-/12-bit ADCs in TSOT package.
2. High throughput with low power consumption.
3. Flexible power/serial clock speed management.
The conversion rate is determined by the serial clock. The
parts also feature a power-down mode to maximize power
efficiency at lower throughput rates. Average power
consumption is reduced when the power-down mode is
used while not converting. Current consumption is 1 µA
maximum and 50 nA typically when in power-down mode.
4. Daisy-chain mode.
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.
1
Protected by U.S. Patent Number 6,681,332.
AD7912/AD7922
Rev. 0 | Page 2 of 32
TABLE OF CONTENTS
Specifications..................................................................................... 3
AD7912 Specifications................................................................. 3
AD7922 Specifications................................................................. 5
Timing Specifications .................................................................. 7
Timing Diagrams.......................................................................... 7
Timing Examples.......................................................................... 8
Absolute Maximum Ratings............................................................ 9
ESD Caution.................................................................................. 9
Pin Configurations and Function Descriptions......................... 10
Terminology .................................................................................... 11
Typical Performance Characteristics ...........................................13
Circuit Information........................................................................ 15
Converter Operation.................................................................. 15
ADC Transfer Function............................................................. 15
Typical Connection Diagram ................................................... 16
Analog Input ............................................................................... 16
Digital Inputs ..............................................................................17
DIN Input.................................................................................... 17
DOUT Output............................................................................ 17
Modes of Operation....................................................................... 18
Normal Mode.............................................................................. 18
Power-Down Mode.................................................................... 18
Power-Up Time .......................................................................... 20
Daisy-Chain Mode..................................................................... 20
Daisy-Chain Example................................................................ 22
Power vs. Throughput Rate........................................................... 24
Serial Interface ................................................................................ 25
Microprocessor Interfacing....................................................... 26
Application Hints ........................................................................... 28
Grounding and Layout .............................................................. 28
Evaluating AD7912/AD7922 Performance................................. 29
Outline Dimensions....................................................................... 30
Ordering Guide .......................................................................... 30
REVISION HISTORY
Revision 0: Initial Version
AD7912/AD7922
Rev. 0 | Page 3 of 32
SPECIFICATIONS
AD7912 SPECIFICATIONS
Temperature range for A Grade from −40°C to +85°C.
V
DD
= 2.35 V to 5.25 V, f
SCLK
= 18 MHz, f
SAMPLE
= 1 MSPS; T
A
= T
MIN
to T
MAX
, unless otherwise noted.
Table 1.
Parameter A Grade
1
Unit Test Conditions/Comments
DYNAMIC PERFORMANCE f
IN
= 100 kHz sine wave
Signal-to- Noise + Distortion (SINAD)
2
61 dB min
Total Harmonic Distortion (THD)
2
−71 dB max
Peak Harmonic or Spurious Noise (SFDR)
2
−72 dB max
Intermodulation Distortion (IMD)
2
Second-Order Terms −82 dB typ fa = 100.73 kHz, fb = 90.7 kHz
Third-Order Terms −83 dB typ fa = 100.73 kHz, fb = 90.7 kHz
Aperture Delay 10 ns typ
Aperture Jitter 30 ps typ
Channel-to-Channel Isolation
2
90 dB typ
Full Power Bandwidth 8.5 MHz typ @ 3 dB
1.5 MHz typ @ 0.1 dB
DC ACCURACY
Resolution 10 Bits
Integral Nonlinearity
2
±0.5 LSB max
Differential Nonlinearity
2
±0.5 LSB max Guaranteed no missed codes to 10 bits
Offset Error
2
±0.5 LSB max
Offset Error Match
2, 3
±0.3 LSB max
Gain Error
2
±0.5 LSB max
Gain Error Match
2, 3
±0.3 LSB max
Total Unadjusted Error (TUE)
2
±0.5 LSB max
ANALOG INPUT
Input Voltage Ranges 0 to V
DD
V
DC Leakage Current ±0.3 µA max
Input Capacitance 20 pF typ
LOGIC INPUTS
Input High Voltage, V
INH
0.7 (V
DD
) V min 2.35 V ≤ V
DD
≤ 2.7 V
2 V min 2.7 V < V
DD
≤ 5.25 V
Input Low Voltage, V
INL
0.3 V max V
DD
= 2.35 V
0.2 (V
DD
) V max 2.35 V < V
DD
≤ 2.7 V
0.8 V max 2.7 V < V
DD
≤ 5.25 V
Input Current, I
IN
, SCLK Pin ±0.3 µA max Typically 8 nA, V
IN
= 0 V or V
DD
Input Current, I
IN
,
CS
Pin
±0.3 µA max
Input Current, I
IN
, DIN Pin ±0.3 µA max
Input Capacitance, C
IN
3
5 pF max
LOGIC OUTPUTS
Output High Voltage, V
OH
V
DD
− 0.2 V min I
SOURCE
= 200 µA, V
DD
= 2.35 V to 5.25 V
Output Low Voltage, V
OL
0.2 V max I
SINK
= 200 µA
Floating-State Leakage Current ±0.3 µA max
Floating-State Output Capacitance
3
5 pF max
Output Coding Straight (natural) binary
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32

AD7922ARMZ

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Manufacturer:
Analog Devices Inc.
Description:
Analog to Digital Converters - ADC 2CH 2.35-5.25V 1 MSPS 12-Bit
Lifecycle:
New from this manufacturer.
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