AD7835AP

Overview

The AD7835AP is a quad 14-bit digital-to-analog converter (DAC) from Analog Devices, utilizing LC2MOS technology. It features parallel data loading with support for both 14-bit straight binary and double-byte (8-bit/6-bit) formats. The device provides four buffered voltage outputs with a maximum span of 14 V and a range of ±8.192 V. Key control signals include LDAC for simultaneous or individual channel updates, CLR for asynchronous clearing to a user-defined sense ground potential, and address pins for channel selection. It operates on dual analog supplies (±12 V to ±15 V) and a single 5 V digital supply.

Feature Summary

• Quad 14-bit resolution with R-2R segmented architecture
• Parallel input interface supporting 14-bit and byte-shift modes
• Output voltage range of ±8.192 V with 14 V maximum span
• Asynchronous clear function to Device Sense Ground (DSG)
• Power-on reset holds outputs within ±2 V of DSG during startup

Applications

• Process control systems
• Automatic test equipment
• General-purpose instrumentation

Procurement Notes

Verify the package type associated with the 'AP' suffix, as the datasheet lists MQFP and PLCC options for the AD7835 series. Confirm availability status, as older LC2MOS components may be discontinued or subject to limited production runs. Ensure supply voltages match the specified ±12 V or ±15 V ranges for optimal performance.

Selection Notes

Select the AD7835AP over the AD7834 if parallel bus interfacing is required rather than serial SPI compatibility. Consider the MQFP or PLCC package constraints for PCB layout. Verify that the system can accommodate the separate reference inputs for DAC pairs A and B if independent scaling is needed, or tie them together for common reference operation.

Part Context

The AD7835 is part of the LC2MOS family of monolithic DACs, designed for high-speed settling and low power consumption compared to bipolar counterparts. It complements the serial-input AD7834 by offering a parallel interface option. The device is engineered for industrial environments with an operating temperature range of -40°C to +85°C.

Replacement Considerations

Direct pin-compatible replacements are not explicitly listed in the provided documentation. Newer generations such as the AD5734R series offer similar quad-channel functionality but may differ in interface protocols (e.g., SPI vs. Parallel) and packaging. Verify electrical compatibility before substitution.

FAQ

How does the AD7835 handle output initialization during power-up?

Internal circuitry holds the DAC output voltage levels to within ±2 V of the Device Sense Ground (DSG) potential until the power supplies stabilize. If the CLR input is exercised, the outputs switch exactly to the DSG potential.

What is the difference between the two reference input pairs on the AD7835?

The AD7835 has separate reference inputs for DAC channels 1 & 2 (VREF(+)A/VREF(-)A) and DAC channels 3 & 4 (VREF(+)B/VREF(-)B). This allows for independent reference scaling or common reference configuration.

Can the AD7835 update all four channels simultaneously?

Yes. By holding the LDAC input high while loading new data into the input registers and then bringing LDAC low, the contents of all four registers are transferred to the DAC latches simultaneously.