Low Cost, 4-Channel, 16-Bit 1 MSPS

AD7655

Rev. B

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FEATURES

4-channel, 16-bit resolution ADC

2 track-and-hold amplifiers

Throughput

1 MSPS (normal mode)

888 kSPS (impulse mode)

Analog input voltage range: 0 V to 5 V

No pipeline delay

Parallel and serial 5 V/3 V interface

SPI®/QSPI™/MICROWIRE™/DSP compatible

Single 5 V supply operation

Power dissipation

120 mW typical

2.6 mW @ 10 kSPS

Package

48-lead quad flat package (LQFP)

48-lead frame chip scale package (LFCSP)

Pin-to-pin compatible with the AD7654

Low cost

APPLICATIONS

AC motor control

3-phase power control

4-channel data acquisition

Uninterrupted power supplies

Communications

FUNCTIONAL BLOCK DIAGRAM

CONTROL LOGIC AND

CALIBRATION CIRCUITRY

A/B

16

D[15:0]

BUSY

CS

SER/PAR

OGND

OVDD

DGND

DVDD

SERIAL

PORT

BYTESWAP

RD

AVDD AGND

REFx

REFGND

PD

RESET

CNVST

INAN

SWITCHED

CAP DAC

AD7655

INA1

IMPULSE

MUX

EOC

INA2

A0

INB1

INBN

INB2

TRACK/HOLD

×2

PARALLEL

INTERFACE

CLOCK

MUX

MUX

Figure 1.

Table 1. PulSAR Selection

Type/kSPS

100 to 250

500 to 570

800 to

1000

>1000

Pseudo

Differential

AD7660/

AD7661

AD7650/

AD7652

AD7664/

AD7666

AD7653

AD7667

True Bipolar

AD7663

AD7665

AD7671

True

Differential

AD7675

AD7676

AD7677

AD7621

AD7623

18 Bit

AD7678

AD7679

AD7674

AD7641

Multichannel/

Simultaneous

AD7654

AD7655

GENERAL DESCRIPTION

The AD7655 is a low cost, simultaneous sampling, dual-

channel, 16-bit, charge redistribution SAR, analog-to-digital

converter that operates from a single 5 V power supply. It

contains two low noise, wide bandwidth, track-and-hold

amplifiers that allow simultaneous sampling, a high speed

16-bit sampling ADC, an internal conversion clock, error

correction circuits, and both serial and parallel system interface

ports. Each track-and-hold has a multiplexer in front to provide

a 4-channel input ADC. The A0 multiplexer control input

allows the choice of simultaneously sampling input pairs

INA1/INB1 (A0 = low) or INA2/INB2 (A0 = high). The part

features a very high sampling rate mode (normal) and, for low

power applications, a reduced power mode (impulse) where the

power is scaled with the throughput. Operation is specified

from −40°C to +85°C.

PRODUCT HIGHLIGHTS

1.

Multichannel ADC.

The AD7655 features 4-channel inputs with two sample-

and-hold circuits that allow simultaneous sampling.

2.

Fast Throughput.

The AD7655 is a 1 MSPS, charge redistribution, 16-bit SAR

ADC with internal error correction circuitry.

3.

Single-Supply Operation.

The AD7655 operates from a single 5 V supply. In impulse

mode, its power dissipation decreases with throughput.

4.

Serial or Parallel Interface.

Versatile parallel or 2-wire serial interface arrangements

are compatible with both 3 V and 5 V logic.