AD7658_15 Datasheet, PDF (1/32 Pages) Analog Devices – 250 kSPS, 6-Channel, Simultaneous

Data Sheet
250 kSPS, 6-Channel, Simultaneous
Sampling, Bipolar 16-/14-/12-Bit ADC
AD7656/AD7657/AD7658
FEATURES
6 independent ADCs
True bipolar analog inputs
Pin-/software-selectable ranges: ±10 V, ±5 V
Fast throughput rate: 250 kSPS
iCMOS process technology
Low power
140 mW at 250 kSPS with 5 V supplies
Wide input bandwidth
86.5 dB SNR at 50 kHz input frequency
On-chip reference and reference buffers
Parallel, serial, and daisy-chain interface modes
High speed serial interface
SPI-/QSPI™-/MICROWIRE™-/DSP-compatible
Standby mode: 100 µW maximum
64-lead LQFP
APPLICATIONS
Power line monitoring systems
Instrumentation and control systems
Multi-axis positioning systems
GENERAL DESCRIPTION
The AD7656/AD7657/AD7658¹ contain six 16-/14-/12-bit,
fast, low power, successive approximation ADCs all in the one
package that is designed on the iCMOS™ process (industrial
CMOS). iCMOS is a process combining high voltage silicon
with submicron CMOS and complementary bipolar technol-
ogies. It enables the development of a wide range of high
performance analog ICs, capable of 33 V operation in a
footprint that no previous generation of high voltage parts
could achieve. Unlike analog ICs using conventional CMOS
processes, iCMOS components can accept bipolar input signals
while providing increased performance, which dramatically
reduces power consumption and package size.
The AD7656/AD7657/AD7658 feature throughput rates up
to 250 kSPS. The parts contain low noise, wide bandwidth,
track-and-hold amplifiers that can handle input frequencies
up to 12 MHz.
FUNCTIONAL BLOCK DIAGRAM
V_DD
CONVST A CONVST B CONVST C AV_CC DV_CC
REF
CLK
OSC
CONTROL
LOGIC
V1 T/H
BUF
16-/14-/12-BIT SAR
OUTPUT
DRIVERS
CS
SER/PAR
V_DRIVE
STBY
DOUT A
V2 T/H
V3 T/H
BUF
16-/14-/12-BIT SAR
16-/14-/12-BIT SAR
OUTPUT
DRIVERS
OUTPUT
DRIVERS
SCLK
DOUT B
DOUT C
V4 T/H
V5 T/H
BUF
16-/14-/12-BIT SAR
16-/14-/12-BIT SAR
OUTPUT
DRIVERS
DATA/
CONTROL
LINES
RD
V6 T/H
WR
16-/14-/12-BIT SAR
AD7656/AD7657/AD7658
V_SS
AGND DGND
Figure 1.
The conversion process and data acquisition are controlled
using CONVST signals and an internal oscillator. Three
CONVST pins allow independent, simultaneous sampling of
the three ADC pairs. The AD7656/AD7657/AD7658 all have
a high speed parallel and serial interface, allowing the devices
to interface with microprocessors or DSPs. In serial interface
mode, the parts have a daisy-chain feature that allows multiple
ADCs to connect to a single serial interface. The AD7656/
AD7657/AD7658 can accommodate true bipolar input signals
in the ±4 × VREF range and ±2 × VREF range. The AD7656/
AD7657/AD7658 also contain an on-chip 2.5 V reference.
PRODUCT HIGHLIGHTS
1. Six 16-/14-/12-bit, 250 kSPS ADCs on board.
2. Six true bipolar, high impedance analog inputs.
3. Parallel and high speed serial interfaces.
1 _{Protected by U.S. Patent No. 6,731,232.}
Rev. D
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