Differential Input, Quad,14-Bit,

Simultaneous Sampling, SAR ADC

Data Sheet

AD7381-4

Rev. 0

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FEATURES

14-bit ADC family

Quad simultaneous sampling

Fully differential analog inputs

Wide common-mode range

High throughput rate: 4 MSPS

Buffered 2.5 V internal voltage reference (10 ppm/°C maximum)

On-chip oversampling function

INL (maximum): 1.5 LSB

SNR (typical)

90.6 dB at OSR = 8× rolling average oversampling, RES = 1

2-bit resolution boost

Out of range indicator (ALERT)

High-speed serial interface

−40°C to +125°C operation

4 mm × 4 mm, 24-lead LFCSP

APPLICATIONS

Motor control position feedback

Motor control current sense

Data acquisition systems

Erbium doped fiber amplifier (EDFA) applications

In phase and quadrature demodulation

FUNCTIONAL BLOCK DIAGRAM

LDO

REF

OVERSAMPLING

OSC

SDOA

SDOB

SDOC

SDOD/

ALERT

SCLK

SDI

CS

GND

GND

REFCAP

REGCAP

REFGND

ADC A

ADC B

ADC C

ADC D

REFIO

OVERSAMPLING

INTERFACE

AND

CONTROL

LOGIC

OVERSAMPLING

OVERSAMPLING

AD7381-4

Figure 1.

GENERAL DESCRIPTION

The AD7381-4 a 16-bit, quad, simultaneous sampling, high

speed, successive approximation register (SAR), analog-to-digital

converter (ADC) that operates from a 3.0 V to 3.6 V power

supply and features throughput rates up to 4 MSPS. The analog

input type is differential, accepts a wide common-mode input

voltage, and the analog inputs are sampled and converted on

the falling edge of CS.

The AD7381-4 has on-chip oversampling blocks to improve

dynamic range and reduce noise at lower bandwidths. The

oversampling can boost up to two bits of added resolution. A

buffered internal 2.5 V reference (10 ppm/°C) is included.

Alternatively, an external reference up to 3.3 V can be used.

The conversion process and data acquisition use standard

control inputs allowing for easy interfacing to microprocessors

or digital signal processors (DSPs). The conversion result can

clock out simultaneously via 4-wire mode for faster throughput

or via 1-wire serial mode when slower throughput is allowed.

The device is compatible with 1.8 V, 2.5 V, and 3.3 V interfaces,

using the separate logic supply.

The AD7381-4 is available in a 24-lead lead frame chip scale

package (LFCSP) with operation specified from −40°C to +125°C.

Table 1. Related Devices

No. of Channels

Input Type

16 Bits

14 Bits

4

Differential

AD7380-4

AD7381-4

AD7389-4

2

Differential

AD7380

AD7381

AD4680

AD4681

Single-ended

AD7386

AD7387

PRODUCT HIGHLIGHTS

1. Quad simultaneous sampling and conversion.

2. Pin-compatible product family.

3. High throughput rate, 4 MSPS at 14-bit.

4. Space-saving, 4 mm × 4 mm LFCSP.

5. Integrated oversampling block to increase dynamic range,

reduce noise and reduce SCLK speed requirements.

6. Differential analog inputs with wide common-mode range.

7. Small sampling capacitor reduces amplifier drive burden.