GENERAL DESCRIPTION

The AD7685 is a 16-bit, charge redistribution successive approximation, analog-to-digital converter (ADC) that operates from a single power supply, VDD, between 2.3 V to 5.5 V. It contains a low power, high speed, 16-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.

FEATURES

16-bit resolution with no missing codes

Throughput: 250 kSPS

INL: ±0.6 LSB typical, ±2 LSB maximum (±0.003 of FSR)

SINAD: 93.5 dB @ 20 kHz

THD: −110 dB @ 20 kHz

Pseudo differential analog input range

0 V to VREF with VREF up to VDD

No pipeline delay

Single-supply operation 2.3 V to 5.5 V with

1.8 V to 5 V logic interface

Serial interface SPI®-/QSPI™-/MICROWIRE™-/DSP-compatible

Daisy-chain multiple ADCs, BUSY indicator

Power dissipation

1.4 μW @ 2.5 V/100 SPS

1.35 mW @ 2.5 V/100 kSPS, 4 mW @ 5 V/100 kSPS

Standby current: 1 nA

10-lead package: MSOP (MSOP-8 size) and

3 mm × 3 mm QFN (LFCSP) (SOT-23 size)

Pin-for-pin-compatible with 10-lead MSOP/QFN PulSAR® ADCs

APPLICATIONS

Battery-powered equipment

Medical instruments

Mobile communications

Personal digital assistants (PDAs)

Data acquisition

Instrumentation

Process controls