LM2904DR2G Dual Operational Amplifier for Whatsminer P21 Power Supply Repair

LM2904DR2G Dual Operational Amplifier – Whatsminer P21 Power Supply Repair

The LM2904DR2G is a low-power dual operational amplifier designed for single-supply operation from 3V to 32V, used in the Whatsminer P21 power supply for voltage regulation feedback, current sensing and signal conditioning. It features low input bias current, an input common-mode range that includes the negative supply rail, integrated ESD clamp protection and continuous short-circuit protection on the output. SMD package for direct board-level replacement.

Role in the P21 Power Supply

Op-amps in a mining PSU sit in the feedback and protection loops — they compare the output voltage against a reference, amplify error signals for the PWM controller, and condition current-sense signals for the overcurrent protection circuit. A failed LM2904 causes the feedback loop to lose regulation, resulting in output voltage drift, oscillation or complete PSU shutdown. Because both amplifier channels are in the same package, a single failure can disable two independent feedback paths simultaneously.

Replacement Procedure

Disconnect mains and discharge capacitors. Locate the LM2904DR2G on the secondary-side feedback/control board of the P21 PSU. Desolder the SMD package, clean pads, install the new device with pin 1 aligned and reflow. Power through a variac and verify stable output voltage under progressive load, confirming the feedback loop is regulating correctly.

LM2904DR2G Op-Amp Specifications

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Repairing P21 power supplies? Contact us at contact@lys-sz.com for op-amps, controllers and all PSU repair ICs.

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