AD7760 Analog Devices Data Sheet Manual

2.5 MSPS, 24-Bit, 100 d B

Sigma-Delta ADC with On-Chip Buffer

AD7760 FEATURES FUNCTIONAL BLOCK DIAGRAM

120 d B dynamic range at 78 k Hz output data rate VIN+VIN–

100 d B dynamic range at 2.5 MHz output data rate

112 d B SNR at 78 k Hz output data rate MULTIBIT AVDD1

DIFF Σ-Δ

100 d B SNR at 2.5 MHz output data rate MODULATOR AVDD2 AVDD3

2.5 MHz maximum fully filtered output word rate

VREF+

BUF RECONSTRUCTION AVDD4

Programmable oversampling rate (8× to 256×)

DECAPA/B

Fully differential modulator input

RBIAS

On-chip differential amplifier for signal buffering

AD7760 PROGRAMMABLE AGND

DECIMATION

Low-pass finite impulse response (FIR) filter with default or VDRIVE

user-programmable coefficients MCLK

CONTROL LOGIC DVDD

Modulator output mode SYNC OFFSET AND GAIN DGND

REGISTERS

Overrange alert bit RESET FIR FILTER ENGINE

Digital offset and gain correction registers Filter bypass modes

DRDYRD/WR DB0 TO DB15CS

Low power and power-down modes

Figure 1.

Synchronization of multiple devices via SYNC pin

APPLICATIONS Data acquisition systems Vibration analysis Instrumentation

www.BDTIC.com/ADI GENERAL DESCRIPTION The AD7760 is a high performance, 24-bit Σ-Δ analog-to-digital coefficients. The sample rate, filter corner frequencies, and output converter (ADC). It combines wide input bandwidth and high word rate are set by a combination of the external clock frequency

speed with the benefits of Σ-Δ conversion to achieve a perfor- and the configuration registers of the AD7760.

mance of 100 d B SNR at 2.5 MSPS, making it ideal for high

The reference voltage supplied to the AD7760 determines the

speed data acquisition. Wide dynamic range combined with

analog input range. With a 4 V reference, the analog input range

significantly reduced antialiasing requirements simplify the

is ±3.2 V differential biased around a common mode of 2 V.

design process. An integrated buffer to drive the reference, a

This common-mode biasing can be achieved using the on-chip

differential amplifier for signal buffering and level shifting, an

differential amplifier, further reducing the external signal

overrange flag, internal gain and offset registers, and a low-pass

conditioning requirements.

digital FIR filter make the AD7760 a compact, highly integrated data acquisition device requiring minimal peripheral component 5-

The AD7760 is available in an exposed paddle, 64-lead TQFP

selection. In addition, the device offers programmable decimation

and is specified over the industrial temperature range from

rates, and the digital FIR filter can be adjusted if the default

−40°C to +85°C.

characteristics are not appropriate for the application. The

Table 1. Related Devices

AD7760 is ideal for applications demanding high SNR

Part No. Description

without a complex front-end signal processing design.

AD7762 24-bit, 625 k SPS, 109 d B, Σ-Δ parallel interface

The differential input is sampled at up to 40 MSPS by an analog AD7763 24-bit, 625 k SPS, 109 d B, Σ-Δ serial interface modulator. The modulator output is processed by a series of low- pass filters, with the final filter having default or user-programmable

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