ALD1721EPAL

Overview

The ALD1721EPAL is a monolithic rail-to-rail precision CMOS operational amplifier featuring integrated user-programmable EPAD offset voltage adjustment. It operates on supply voltages from ±1V to ±5V (single supply 2V to 10V). Key electrical parameters include a typical input bias current of 0.01pA, an initial input offset voltage of 35µV, and a bandwidth of up to 1MHz at ±5V. The device offers a slew rate of 1V/µs and draws 120µA of supply current. It supports in-system programming for total input offset voltage compensation.

Feature Summary

• Integrates Electrically Programmable Analog Device (EPAD) technology for permanent, computer-assisted offset voltage trimming without external components.
• Provides rail-to-rail input and output voltage ranges with tolerance to over-voltage input spikes beyond supply rails.
• Achieves extremely low input bias currents and high open-loop gain suitable for high-impedance signal sources.
• Supports application-specific and in-system programming modes to compensate for system-level errors such as PSRR, CMRR, and temperature drift.

Applications

• Sensor interface circuits
• Biochemical probe interfaces
• Precision sample and hold amplifiers
• High source impedance electrode amplifiers
• Portable instruments

Procurement Notes

Verify the specific package variant, as the ALD1721E series includes SOIC (ESAL), PDIP (EPAL), and CERDIP (EDA) options. Confirm that the design accommodates the required programming pulses via the VE1 and VE2 pins using an EPAD programmer. Ensure static control procedures are observed due to ESD sensitivity. Check if the application requires the standard commercial temperature range or the extended industrial range available in other suffixes.

Selection Notes

Select this component when system accuracy requires elimination of manual trimming and chopper noise. It is suitable for designs needing micropower operation with rail-to-rail performance. Consider the need for in-system calibration capabilities to correct for external component tolerances and environmental drift. Verify that the 50pF capacitive load limit meets the circuit requirements.

Part Context

The ALD1721EPAL belongs to the ALD1721E family of micropower CMOS operational amplifiers. It serves as a direct replacement for the ALD1701 but adds user-programmable offset voltage trimming. The 'PAL' suffix specifically denotes the 8-pin Plastic DIP package with lead-free (RoHS) compliant terminals. It utilizes exclusive EPAD technology to store trim settings indefinitely after power-down.

Replacement Considerations

The datasheet identifies the ALD1701 as a predecessor. No other specific substitute part numbers are documented in the provided source material.

FAQ

How is the offset voltage programmed?

The offset voltage is adjusted by injecting charge into internal EPADs via the VE1 and VE2 pins using an ALD E100 EPAD Programmer and appropriate adapter module under software control.

What happens to the VE1 and VE2 pins after programming?

After programming, the VE1 and VE2 terminals must be left open to settle on a voltage determined by internal bias currents. They should be shielded from digital signals to prevent unwanted offset fluctuations.

Can the device handle capacitive loads?

Yes, the ALD1721E is internally compensated for unity gain stability and can typically drive up to 50pF of external load capacitance.