Differential Input, Dual, Simultaneous

Sampling, 4.2 MSPS, 14-Bit, SAR ADC

Data Sheet

AD7357

Rev. E

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FEATURES

Dual 14-bit SAR ADC

Simultaneous sampling

Throughput rate: 4.2 MSPS per channel

Power dissipation: 36 mW at 4.2 MSPS

On-chip reference: 2.048 V ± 0.25%, 6 ppm/°C

Dual conversion with read

High speed serial interface

SPI-/QSPI-/MICROWIRE-/DSP-compatible

−40°C to +125°C Y grade operation, −40°C to +85°C B grade

operation

16-lead TSSOP and 18-lead LFCSP packages

Qualified for automotive applications

APPLICATIONS

Automotive radar

Data acquisition systems

Motion control

I and Q demodulation

RFID readers

FUNCTIONAL BLOCK DIAGRAM

SCLK

AD7357

14-BIT

SUCCESSIVE

APPROXIMATION

ADC

14-BIT

SUCCESSIVE

APPROXIMATION

ADC

CONTROL

LOGIC

CS

DGND

REFGND

AGND

AGND

T/H

T/H

BUF

BUF

REF

Figure 1.

GENERAL DESCRIPTION

The AD73571 is a dual, 14-bit, high speed, low power, successive

approximation analog-to-digital converter (ADC) that operates

from a single 2.5 V power supply and features throughput rates

up to 4.2 MSPS. The device contains two ADCs, each preceded

by a low noise, wide bandwidth track-and-hold circuit that can

handle input frequencies in excess of 110 MHz.

The conversion process and data acquisition use standard control

inputs allowing for easy interfacing to microprocessors or

digital signal processors (DSPs). The input signal is sampled on

the falling edge of CS; a conversion is also initiated at this point.

The conversion time is determined by the SCLK frequency.

The AD7357 uses advanced design techniques to achieve very

low power dissipation at high throughput rates. With a 2.5 V

supply and a 4.2 MSPS throughput rate, the device consumes

14 mA typically. The device also offers flexible power and

throughput rate management options.

The analog input range for the device is the differential common

that can be overdriven when an external reference is preferred.

The AD7357 is available in a 16-lead thin shrink small outline

package (TSSOP) and an 18-lead lead frame chip scale package

(LFCSP).

PRODUCT HIGHLIGHTS

1. Two Complete ADC Functions.

These functions allow simultaneous sampling and conversion

of two channels. The conversion result of both channels

is simultaneously available on separate data lines or in

succession on one data line if only one serial port is available.

2. High Throughput with Low Power Consumption.

The AD7357 offers a 4.2 MSPS throughput rate with 36 mW

power consumption.

3. Simultaneous Sampling.

The device features two standard successive approximation

ADCs with accurate control of the sampling instant via a CS

input and once off conversion control.

Table 1. Related Devices

Generic

Resolution

Throughput

Analog Input

AD7356

12-bit

5 MSPS

Differential

AD7352

12-bit

3 MSPS

Differential

AD7266

12-bit

2 MSPS

Differential/single-

ended

AD7866

12-bit

1 MSPS

Single-ended

AD7366

12-bit

1 MSPS

Single-ended bipolar

AD7367

14-bit

1 MSPS

Single-ended bipolar

1

Protected by U.S. Patent No. 6,681,332.