14-Bit, 500 kSPS,

PulSAR ADC in MSOP and LFCSP

Data Sheet

AD7946

FEATURES

14-bit resolution with no missing codes

Throughput: 500 kSPS

INL: ±0.4 LSB typical, ±1 LSB maximum (±0.0061% of FSR)

SINAD: 85 dB at 20 kHz

THD: −100 dB at 20 kHz

Pseudo differential analog input range

0 V to REF with REF up to VDD

No pipeline delay

Single-supply 5 V operation with 1.8 V/2.5 V/3 V/5 V logic

interface

Proprietary serial interface

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

Daisy-chain multiple ADCs and BUSY indicator

Power dissipation

3.3 mW at 5 V/100 kSPS

3.3 µW at 5 V/100 SPS

Standby current: 1 nA

10-lead MSOP (MSOP-8 size) and

3 mm × 3 mm LFCSP (SOT-23 size)

Pin-for-pin compatible with the 16-bit AD7686

APPLICATIONS

Battery-powered equipment

Data acquisition

Instrumentation

Medical instruments

Process control

TYPICAL APPLICATION CIRCUIT

AD7946

REF

GND

VDD

IN+

IN–

VIO

SDI

SCK

SDO

CNV

1.8V TO VDD

3- OR 4-WIRE INTERFACE

(SPI, DAISY CHAIN, CS)

0.5V TO 5V

5V

0V TO REF

Figure 1.

GENERAL DESCRIPTION

The AD79461 is a 14-bit, charge redistribution, successive

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

from a single 5 V power supply, VDD. It contains a low power,

high speed, 14-bit sampling ADC with no missing codes, an

internal conversion clock, and a versatile serial interface port.

The part also contains a low noise, wide bandwidth, short

aperture delay track-and-hold circuit. On the CNV rising edge,

it samples an analog input IN+ between 0 V to REF with respect

to a ground sense IN−. The reference voltage, REF, is applied

externally and can be set up to the supply voltage.

Its power scales linearly with throughput.

The SPI-compatible serial interface also features the ability,

using the SDI input, to daisy-chain several ADCs on a single,

3-wire bus, or it provides an optional BUSY indicator. It is

compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate

supply VIO.

The AD7946 is housed in a 10-lead MSOP or a 10-lead LFCSP

with operation specified from −40°C to +85°C.

1

Protected by U.S. Patent 6,703,961.

Table 1. MSOP, LFCSP 14-/16-/18-Bit PulSAR® ADC

Type

100 kSPS

250 kSPS

400 kSPS to 500 kSPS

≥1000 kSPS

ADC Driver

14-Bit

AD7940

AD79421

AD79461

16-Bit

AD7680

AD76851

AD76861

AD79801

ADA4941

AD7683

AD76871

AD76881

AD79831

ADA4841

AD7684

AD7694

AD76931

18-Bit

AD76911

AD76901

AD79821

ADA4941

AD79841

ADA4841

1

Pin-for-pin compatible.

Rev. B

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