AD7856 Datasheet, PDF (1/32 Pages) Analog Devices – 5 V Single Supply, 8-Channel 14-Bit 285 kSPS Sampling ADC

a
5 V Single Supply, 8-Channel
14-Bit 285 kSPS Sampling ADC
AD7856
FEATURES
Single 5␣ V Supply
285 kSPS Throughput Rate
Self- and System Calibration with Autocalibration on
Power-Up
Eight Single-Ended or Four Pseudo-Differential Inputs
Low Power: 60 mW Typ
Automatic Power-Down After Conversion (2.5␣ ␮W Typ)
Flexible Serial Interface: 8051/SPI™/QSPI™/␮P Compatible
24-Lead DIP, SOIC and SSOP Packages
APPLICATIONS
Battery-Powered Systems (Personal Digital Assistants,
Medical Instruments, Mobile Communications)
Pen Computers
Instrumentation and Control Systems
High Speed Modems
FUNCTIONAL BLOCK DIAGRAM
AV_DD
AGND
AIN1
AIN8
REF_IN/REF_OUT
C_REF1
C_REF2
CAL
I/P
MUX
T/H
4.096V
REFERENCE
BUF
AD7856
COMP
CHARGE
REDISTRIBUTION
DAC
CALIBRATION
MEMORY AND
CONTROLLER
SAR + ADC
CONTROL
DV_DD
DGND
CLKIN
CONVST
BUSY
SLEEP
GENERAL DESCRIPTION
The AD7856 is a high speed, low power, 14-bit ADC that oper-
ates from a single 5 V power supply. The ADC powers up with
a set of default conditions at which time it can be operated as a
read only ADC. The ADC contains self-calibration and system
calibration options to ensure accurate operation over time and
temperature and it has a number of power-down options for low
power applications.
The AD7856 is capable of 285 kHz throughput rate. The input
track-and-hold acquires a signal in 500 ns and features a pseudo-
differential sampling scheme. The AD7856 voltage range is 0 to
V_REF with straight binary output coding. Input signal range is to
the supply and the part is capable of converting full power sig-
nals to 10 MHz.
CMOS construction ensures low power dissipation of typically
60 mW for normal operation and 5.1 mW in power-down mode
at 10 kSPS throughput rate. The part is available in 24-lead,
0.3 inch-wide dual in-line package (DIP), 24-lead small outline
(SOIC) and 24-lead small shrink outline (SSOP) packages.
Please see page 31 for data sheet index.
SERIAL INTERFACE/CONTROL REGISTER
SYNC
DIN
DOUT
SCLK
PRODUCT HIGHLIGHTS
1. Single 5 V supply.
2. Automatic calibration on power-up.
3. Flexible power management options including automatic
power-down after conversion.
4. Operates with reference voltages from 1.2 V to V_DD.
5. Analog input range from 0 V to V_DD.
6. Eight single-ended or four pseudo-differential input channels.
7. Self- and system calibration.
8. Versatile serial I/O port (SPI/QSPI/8051/µP).
SPI and QSPI are trademarks of Motorola, Inc.
REV. A
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone]
© Analog Devices, Inc., 1998