2.7 V to 5.25 V, Micropower, 2-Channel,
125 kSPS, 12-Bit ADC in 8-Lead MSOP
AD7887
FEATURES FUNCTIONAL BLOCK DIAGRAM
Specified for V of 2.7 V to 5.25 V
DD
AD7887
AIN0
Flexible power/throughput rate management I/P
T/H
MUX
Shutdown mode: 1 A max
AIN1/
One or two single-ended inputs
V
REF
2.5V
Serial interface: SPI/QSPI/MICROWIRE/DSP compatible COMP
REF
8-lead narrow SOIC and MSOP packages
AIN1/V
REF
SOFTWARE
V
BUF
DD
CONTROL
APPLICATIONS
LATCH
Battery-powered systems (personal digital assistants,
GND
CHARGE
medical instruments, mobile communications) REDISTRIBUTION
DAC
Instrumentation and control systems
High speed modems
SAR + ADC
CONTROL LOGIC
SPORT
DIN CS DOUT SCLK
Figure 1.
GENERAL DESCRIPTION
The AD7887 is a high speed, low power, 12-bit analog-to-digital a result, the input voltage range on both the AIN0 and AIN1
converter (ADC) that operates from a single 2.7 V to 5.25 V inputs is 0 to VDD.
power supply. The AD7887 is capable of 125 kSPS throughput
CMOS construction ensures low power dissipation of typically
rate. The input track-and-hold acquires a signal in 500 ns and
2 mW for normal operation and 3 W in power-down mode.
features a single-ended sampling scheme. The output coding for
The part is available in an 8-lead, 0.15-inch-wide narrow body
the AD7887 is straight binary, and the part is capable of
SOIC and an 8-lead MSOP package.
converting full power signals of up to 2.5 MHz.
PRODUCT HIGHLIGHTS
The AD7887 can be configured for either dual- or single-channel
1. Smallest 12-bit dual-/single-channel ADC; 8-lead MSOP
operation via the on-chip control register. There is a default
package.
single-channel mode that allows the AD7887 to be operated as a
read-only ADC. In single-channel operation, there is one 2. Lowest power 12-bit dual-/single-channel ADC.
analog input (AIN0) and the AIN1/V pin assumes its V
REF REF
3. Flexible power management options, including automatic
function. This V pin allows the user access to the parts
REF
power-down after conversion.
internal 2.5 V reference, or the V pin can be overdriven by an
REF
4. Read-only ADC capability.
external reference to provide the reference voltage for the part.
This external reference voltage has a range of 2.5 V to VDD. The 5. Analog input range from 0 V to VREF.
analog input range on AIN0 is 0 to VREF.
6. Versatile serial input/output port (SPI/QSPI/MICROWIRE/
In dual-channel operation, the AIN1/VREF pin assumes its AIN1 DSP compatible).
function, providing a second analog input channel. In this case,
the reference voltage for the part is provided via the V pin. As
DD
Rev. D
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
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rights of third parties that may result from its use. Specifications subject to change without notice. No
Tel: 781.329.4700 www.analog.com
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Fax: 781.461.3113 2009 Analog Devices, Inc. All rights reserved.
Trademarks and registered trademarks are the property of their respective owners.
06191-001AD7887
TABLE OF CONTENTS
Features .............................................................................................. 1 Theory of Operation ...................................................................... 11
Applications ....................................................................................... 1 Circuit Information .................................................................... 11
Functional Block Diagram .............................................................. 1 Converter Operation .................................................................. 11
General Description ......................................................................... 1 ADC Transfer Function ............................................................. 11
Product Highlights ........................................................................... 1 Typical Connection Diagram ................................................... 11
Revision History ............................................................................... 2 Analog Input ............................................................................... 12
Specif icat ions ..................................................................................... 3 Power-Down Options ................................................................ 13
Timing Specifications .................................................................. 5 Power vs. Throughput Rate ....................................................... 13
Absolute Maximum Ratings ............................................................ 6 Modes of Operation ................................................................... 13
ESD Caution .................................................................................. 6 Serial Interface ............................................................................ 17
Pin Configurations and Function Descriptions ........................... 7 Microprocessor Interfacing ....................................................... 18
Typical Performance Characteristics ............................................. 8 Application Hints ....................................................................... 20
Terminology ...................................................................................... 9 Outline Dimensions ....................................................................... 21
Control Register .............................................................................. 10 Ordering Guide .......................................................................... 21
REVISION HISTORY
2/09Rev. C to Rev. D
Changes to Ordering Guide .......................................................... 21
9/06Rev. B to Rev. C
Updated Format .................................................................. Universal
Change to Absolute Maximum Ratings ......................................... 6
Additions to Pin Configurations .................................................... 7
Added Table 7 .................................................................................. 18
Updated Outline Dimensions ....................................................... 21
Changes to Ordering Guide .......................................................... 21
Rev. D | Page 2 of 24