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LM3150: Output Voltage turns off then back on off by itself, results in square wave on output signal

Part Number: LM3150


I am having an intermittent issue with our LM3150. Input voltage is +24v and the output voltage can be +7v to +15v at 3A. Sometimes the LM3150 will output full +15v and other times the output will shut off (evidence that LM3150 shuts off) and back on resulting in a +7v to +12v square wave. I have attached a screenshot of the LM3150 circuit with surrounding components. Please let me know if you have any thoughts. Case Temperature of LM3150 is cool and not warm. Thanks in advance. Oscilloscope screenshot below of +V_DCDC_HV. 

  • Hi,

    The first thing I would do here is disconnect the INA111BU circuit and hard tie the feedback of the top and bottom resistor (R627 and R628) directly onto Pin 4 to see if output voltage is regulated and SW frequency is constant first. If the circuit is regulating and stable, then the next thing to look at is the INA111BU control and how it is impacting the output voltage regulating from the CTRL_HV trail. 

    If you want to dynamically control output voltage, you can try to implement it by using an external DAC, refer to app note ( Current injection into the FB node lowers the output voltage regulation point.