AD7880BRZ

Overview

The AD7880BRZ is a monolithic 12-bit analog-to-digital converter (ADC) fabricated in Analog Devices' LC2MOS process. It operates from a single +5 V supply and features a throughput rate of 66 kS/s with a conversion time of 12 μs and an acquisition time of 3 μs. The device includes an on-chip track/hold amplifier, successive-approximation architecture, and three-state digital outputs. It supports multiple input ranges including 0 to VREF, 0 to 2VREF, and ±VREF. Key electrical specifications include a signal-to-noise ratio of 70 dB minimum, integral nonlinearity of ±1 LSB, and differential nonlinearity of ±1 LSB. Power consumption is 25 mW typically in normal mode and 2 mW in power save mode.

Feature Summary

• Supports multiple user-defined analog input ranges (unipolar and bipolar) using a single +5 V supply via internal resistor networks.
• Integrates a low-power successive-approximation ADC with a fast track/hold amplifier for high-speed data acquisition.
• Features a dedicated power save mode that significantly reduces current consumption for battery-operated applications.
• Provides versatile parallel interface logic compatible with standard microprocessors and DSPs.

Applications

• Battery-powered portable systems requiring low power consumption
• Digital signal processing and speech recognition circuits
• High-speed modem interfaces
• Industrial control and instrumentation systems

Procurement Notes

Verify the specific suffix 'R' indicates the SOIC package variant when sourcing replacements or verifying stock. Confirm the temperature grade corresponds to the industrial range (-40°C to +85°C). Ensure the voltage reference input is properly decoupled and tied to VDD for specified performance levels. Check for ESD sensitivity precautions during handling.

Selection Notes

Select this component when a single-supply 12-bit resolution is required with moderate speed up to 66 kS/s. Consider the available input ranges if bipolar signals must be processed without negative supply rails. Evaluate the power save feature against system duty cycles to optimize battery life. Ensure the microprocessor interface timing matches the 57 ns data access time specification.

Part Context

The AD7880 belongs to the AD7880 series of low-power sampling ADCs. It is distinct from higher-speed variants like the AD7874 or multi-channel devices like the AD7890. The BRZ designation specifically denotes the industrial temperature range and lead-free SOIC packaging within the broader family of monolithic A/D converters offered by Analog Devices.

Replacement Considerations

AD7880CNZ: Plastic DIP package variant with identical electrical characteristics.

FAQ

How are the different analog input ranges configured?

The AD7880 supports 0 to VREF, 0 to 2VREF, and ±VREF ranges. These are achieved by connecting the VINB pin to AGND for the 0 to 2VREF range or to VREF for the ±VREF range, while keeping VINA as the primary signal input.

What is the function of the MODE pin?

The MODE pin controls the power state of the device. Driving it to VDD enables normal operation, while pulling it to 0 V activates the power save mode, reducing power dissipation to approximately 2 mW.

Can the AD7880 operate with a clock frequency lower than 2.5 MHz?

Yes, but accuracy may degrade. Lowering the clock frequency increases leakage effects on the hold capacitor, which can negatively impact linearity error as shown in the datasheet graphs.