ADM1281-3ACPZ

Overview

The ADM1281-3ACPZ is a low-voltage hot swap controller manufactured by Analog Devices Inc. It features an integrated 12-bit ADC for monitoring current, power, voltage, and temperature via a PMBus interface. The device operates within a supply voltage range of 4.5 V to 20 V and functions in temperatures from -40°C to +85°C. It utilizes a 32-lead LFCSP package and includes an internal current sense amplifier with a default limit of 20 mV, adjustable between 5 mV and 25 mV. The controller supports constant power foldback and offers programmable start-up limits.

Feature Summary

• Integrated 12-bit ADC provides high-precision back-read capability for load current, input/output voltage, and die temperature.
• Supports constant power foldback to enforce stricter FET Safe Operating Area (SOA) protection during fault conditions.
• Features a RETRY pin configurable for automatic retry or latch-off behavior following overcurrent events.
• Includes PROCHOT functionality for processor thermal throttling and independent inputs for external ADC filtering.

Applications

• Server blade insertion and removal
• Telecommunications and data communication equipment
• Power budgeting and monitoring systems

Procurement Notes

Verify the specific suffix '3' against official documentation to confirm configuration differences from standard variants. Confirm availability status as distribution channels may list limited stock. Ensure compatibility with existing PCB footprints and thermal management requirements for the LFCSP-32 package before finalizing procurement decisions.

Selection Notes

Select this component when precise power monitoring and PMBus integration are required for hot swap applications. Consider the 290 ns short-circuit response time for fast fault protection. Evaluate the need for remote temperature detection thresholds and the specific current sense resistor voltage range suitable for the target load profile.

Part Context

This part belongs to the ADM1281 series of low-voltage hot swap controllers designed for protecting circuits during board insertion into live backplanes. It serves as a direct replacement for older models like the ADM1278 while offering enhanced digital monitoring capabilities through its integrated ADC and communication interface.

Replacement Considerations

The ADM1281 is documented as a direct replacement for the ADM1278. Verify pinout compatibility and software register mapping if migrating from legacy controllers within the same product family.

FAQ

How is the current limit adjusted on the ADM1281?

The current limit is set by the voltage across the sense resistor and is programmable via external resistors, allowing a VSENSE range from 5 mV to 25 mV.

What protection mechanism does the ADM1281 use for FET SOA?

It employs constant power foldback to ensure the FET remains within its Safe Operating Area during fault conditions.