3 V to 5 V Single Supply, 200 kSPS
8-Channel, 12-Bit Sampling ADC
a
AD7858/AD7858L*
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Specified for VDD of 3 V to 5.5 V
AD7858—200 kSPS; AD7858L—100 kSPS
System and Self-Calibration with Autocalibration on
Power-Up
Eight Single-Ended or Four Pseudo-Differential Inputs
Low Power
AV
DD
AGND
AIN1
AIN8
AD7858/
AD7858L
I/P
MUX
T/H
DV
DD
AD7858: 12 mW (VDD = 3 V)
AD7858L: 4.5 mW (VDD = 3 V)
2.5V
REFERENCE
COMP
Automatic Power-Down After Conversion (25 ?W)
Flexible Serial Interface:
DGND
REF /REF
IN
BUF
OUT
8051/SPI?/QSPI?/?P Compatible
24-Lead DIP, SOIC, and SSOP Packages
C
REF1
CHARGE
REDISTRIBUTION
DAC
APPLICATIONS
Battery-Powered Systems (Personal Digital Assistants,
Medical Instruments, Mobile Communications)
Pen Computers
Instrumentation and Control Systems
High-Speed Modems
CLKIN
C
REF2
CONVST
SAR AND ADC
CONTROL
CALIBRATION
MEMORY AND
CONTROLLER
BUSY
CAL
SLEEP
GENERAL DESCRIPTION
SERIAL INTERFACE/CONTROL REGISTER
The AD7858/AD7858L are high-speed, low-power, 12-bit
ADCs that operate from a single 3 V or 5 V power supply, the
AD7858 being optimized for speed and the AD7858L for low
power. 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 en-
sure accurate operation over time and temperature and have a
number of power-down options for low-power applications.
The part powers up with a set of default conditions and can
operate as a read-only ADC.
DIN
DOUT
SCLK
SYNC
PRODUCT HIGHLIGHTS
1. Specified for 3 V and 5 V supplies.
2. Automatic calibration on power-up.
3. Flexible power management options including automatic
power-down after conversion.
The AD7858 is capable of 200 kHz throughput rate while the
AD7858L is capable of 100 kHz throughput rate. The input
track-and-hold acquires a signal in 500 ns and features a
pseudo-differential sampling scheme. The AD7858/AD7858L
voltage range is 0 to VREF with straight binary output coding.
Input signal range is to the supply and the part is capable of con-
verting full power signals to 100 kHz.
4. Operates with reference voltages from 1.2 V to VDD
5. Analog input range from 0 V to VDD
.
.
6. Eight single-ended or four pseudo-differential input channels.
7. System and self-calibration.
8. Versatile serial I/O port (SPI/QSPI/8051/μP).
9. Lower power version AD7858L.
CMOS construction ensures low power dissipation of typically
4.5 mW for normal operation and 1.15 mW in power-down
mode with a throughput rate of 10 kSPS (VDD = 3 V). 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.
*Patent pending.
See page 31 for data sheet index.
SPI and QSPI are trademarks of Motorola, Inc.
REV. B
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: 781/329-4700
Fax: 781/326-8703
World Wide Web Site: http://www.analog.com
? Analog Devices, Inc., 2000
ADI [ ADI ]
