AD7821 View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

AD7821

LC2MOS High Speed, μ
P Compatible 8-Bit ADC with Track/Hold Function

Analog Devices 

AD7821

Figure 21. 16-Channel Telecom ADC System

SIMULTANEOUS SAMPLING ADCS

The AD7821’s inherent track-and-hold and well defined sampling

instant makes it useful in such applications as sonar, where a num-

ber of input channels are required to be sampled simultaneously.

Figure 22 shows a circuit for such an application.

Figure 22. Simultaneous Sampling ADCs

The actual sampling instant at which VIN is measured occurs

approximately 50 ns after the falling edge of WR or RD in the

WR-RD or RD modes, respectively, due to internal logic delays.

However, the internal logic delay and, therefore, the sampling

instant can vary from device to device, but is typically within ±5 ns.

This means that a maximum common input sine wave of ± 2.5 V

at 32 kHz, applied to any number of AD7821s in the circuit of

Figure 22, will yield a maximum difference between the converter

outputs of typically ± 1/4 LSB.

REV. B

–13–

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