AD7828LN

Overview

The AD7828LN is an 8-bit, 8-channel analog-to-digital converter utilizing a half-flash architecture. It features a built-in track-and-hold circuit capable of handling input signals up to 10 kHz with a slew rate of 157 mV/µs. The device operates from a single 5 V supply and achieves a conversion time of 2.5 µs per channel. It provides a total unadjusted error of ±1/2 LSB and interfaces via standard microprocessor control signals without requiring an external clock.

Feature Summary

• Half-flash conversion technique eliminates the need for an external ADC clock signal.
• Built-in track-and-hold function enables direct digitization of high-speed signals up to 10 kHz.
• Standard microprocessor interface allows connection using Chip Select and Read signals.
• Tight channel-to-channel matching specifications remove the requirement for user calibration.

Applications

• Multichannel data acquisition systems
• Industrial process control monitoring
• Microprocessor-based measurement instrumentation

Procurement Notes

Verify the specific suffix LN indicates the commercial temperature range (0°C to 70°C) and ±1/2 LSB accuracy grade. Confirm package availability matches the required footprint, as this component is available in DIP, SOIC, SSOP, PLCC, and LCCC options. Check current lifecycle status as older revisions may have limited distribution channels.

Selection Notes

Select the AD7828LN when eight multiplexed channels are required with moderate speed and high accuracy. Ensure the driving source impedance is low enough to charge the internal capacitors within the tracking window. Verify that the system timing supports Mode 0 or Mode 1 operation based on microprocessor capabilities.

Part Context

This component belongs to the AD7824/AD7828 family of high-speed multichannel ADCs. The AD7828 variant specifically provides eight analog inputs compared to the four found in the AD7824. Both share identical electrical characteristics and conversion architectures, differing only in channel count and pin configuration.

Replacement Considerations

The AD7828LP serves as a direct replacement offering the same performance with improved accuracy. Other family members like the AD7828KN provide standard accuracy. Cross-reference pinouts carefully if substituting with surface-mount variants such as the AD7828LRS.

FAQ

Does the AD7828 require an external clock signal for operation?

No, the half-flash conversion technique allows the device to operate without an external clock signal, simplifying microprocessor interfacing.

What is the maximum input signal frequency the AD7828 can handle directly?

The built-in track-and-hold function allows the AD7828 to digitize full-scale signals with frequencies up to 10 kHz.

How does the RDY output behave in Mode 0 operation?

In Mode 0, the RDY output goes low on the falling edge of CS and returns to high impedance at the end of conversion to indicate data validity.