3 V to 5 V Single Supply, 200 kSPS
12-Bit Sampling ADCs
a
AD7854/AD7854L*
FUNCTIONAL BLOCK DIAGRAM
FEATURES
AV
DD
AGND
Specified for VDD of 3 V to 5.5 V
Read-Only Operation
AD7854–200 kSPS; AD7854L–100 kSPS
System and Self-Calibration
Low Power
AIN(+)
AIN(–)
AD7854/AD7854L
T/H
DV
DD
2.5V
REFERENCE
Normal Operation
AD7854: 15 mW (VDD = 3 V)
AD7854L: 5.5 mW (VDD = 3 V)
Automatic Power-Down After Conversion (25 W)
AD7854: 1.3 mW 10 kSPS
AD7854L: 650 W 10 kSPS
Flexible Parallel Interface
COMP
REF
IN
/
BUF
REF
OUT
DGND
CLKIN
C
REF1
CHARGE
REDISTRIBUTION
DAC
12-Bit Parallel/8-Bit Parallel (AD7854)
28-Lead DIP, SOIC and SSOP Packages (AD7854)
SAR + ADC
CONTROL
CONVST
C
REF2
CALIBRATION
MEMORY
BUSY
APPLICATIONS
AND CONTROLLER
Battery-Powered Systems (Personal Digital Assistants,
Medical Instruments, Mobile Communications)
Pen Computers
PARALLEL INTERFACE/CONTROL REGISTER
Instrumentation and Control Systems
High Speed Modems
HBEN
CS
WR
DB11–DB0
RD
GENERAL DESCRIPTION
PRODUCT HIGHLIGHTS
1. Operation with either 3 V or 5 V power supplies.
The AD7854/AD7854L is a high speed, low power, 12-bit ADC
that operates from a single 3 V or 5 V power supply, the
AD7854 being optimized for speed and the AD7854L 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 has a
number of power-down options for low power applications.
2. Flexible power management options including automatic
power-down after conversion. By using the power manage-
ment options a superior power performance at slower
throughput rates can be achieved:
AD7854: 1 mW typ @ 10 kSPS
AD7854L: 1 mW typ @ 20 kSPS
3. Operates with reference voltages from 1.2 V to AVDD
4. Analog input ranges from 0 V to AVDD
.
The AD7854 is capable of 200 kHz throughput rate while the
AD7854L 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 AD7854 and AD7854L input
voltage range is 0 to VREF (unipolar) and –VREF/2 to +VREF/2,
centered at VREF/2 (bipolar). The coding is straight binary in
unipolar mode and twos complement in bipolar mode. Input
signal range is to the supply and the part is capable of convert-
ing full-power signals to 100 kHz.
.
5. Self-calibration and system calibration.
6. Versatile parallel I/O port.
7. Lower power version AD7854L.
CMOS construction ensures low power dissipation of typically
5.4 mW for normal operation and 3.6 µW in power-down mode.
The part is available in 28-lead, 0.6 inch wide dual-in-line pack-
age (DIP), 28-lead small outline (SOIC) and 28-lead small
shrink outline (SSOP) packages.
*Patent pending.
See Page 27 for data sheet index.
REV. B
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