a
LC2MOS
16-Bit, High Speed Sampling ADCs
AD7884/AD7885
FUNCTIONAL BLOCK DIAGRAMS
FEATURES
Monolithic Construction
Fast Conversion: 5.3 s
High Throughput Rate: 166 kSPS
Low Power: 250 mW
APPLICATIONS
Automatic Test Equipment
Medical Instrumentation
Industrial Control
Data Acquisition Systems
Robotics
؎3VINF ؎3VINS
؎5VINF
R3
3k⍀ C1
R2
3k⍀
؎5VINS
AD7884
R1
5k⍀
SW1
R4
4k⍀
R6
2k⍀
AGNDS AGNDF AVDD AVSS VDD VSS
R5
4k⍀
A1
SW2
9-BIT
ADC
VREF–
O
U
LATCH
T
16 P
+
U
ALU
T
9
9
D
R
I
V 16
E
R
S
DB15
DB0
A2
SW3
16-BIT
ACCURATE
DAC
9
TIMER
The AD7884/AD7885 has its own internal oscillator that controls
conversion. It runs from ±5 V supplies and needs a VREF+ of 3 V.
The AD7884 is available in a 40-lead CERDIP package and a
44-lead PLCC package.
CS
RD
R7
2k⍀
GENERAL DESCRIPTION
The AD7884/AD7885 is a 16-bit monolithic analog-to-digital
converter with internal sample-and-hold and a conversion time
of 5.3 µs. The maximum throughput rate is 166 kSPS. It uses a
two-pass flash architecture to achieve this speed. Two input
ranges are available: ± 5 V and ± 3 V. Conversion is initiated by
the CONVST signal. The result can be read into a microprocessor
using the CS and RD inputs on the device. The AD7884 has a
16-bit parallel reading structure while the AD7885 has a byte reading
structure. The conversion result is in twos complement code.
CONTROL
R8
2k⍀
VREF+F
VREF+S VINV
VREF– GND CONVST BUSY
؎3VIN
AGNDS AGNDF AVDD AVSS VDD VSS
R3
3k⍀ C1
R2
3k⍀
؎5VINS
؎5VINF
DGND
AD7885
R1
5k⍀
R6
2k⍀
SW1
R4
4k⍀
R5
4k⍀
A1
SW2
9-BIT
ADC
VREF–
The AD7885 is available in a 28-lead CERDIP package and the
AD7885A is available in a 44-lead PLCC package.
OD
UR
LATCH
T I
16 P V
+
E
UR
ALU
T S
9
DB7
9
8
DB0
A2
SW3
16-BIT
ACCURATE
DAC
9
TIMER
CONTROL
CS
RD
R7
2k⍀
HBEN
R8
2k⍀
VREF+F
VREF+S VINV
VREF– GND CONVST BUSY
DGND
REV. E
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