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Original question:

LM258: LM258DR MARKING

LM258: LM258DR ，Review schematic

kevin.huang_FJXM
Expert 2925 points

Part Number: LM258

hi team:

1. Please help to  review the schematic 

2. The power supply voltage input is 24 V, and the signal voltage input is 0-3.3 v

3. The defective products are sent to the terminal customers after the normal trial production (including function test) in the customer's factory, with a total of 20 PCs. the feedback of such defective products is 1pcs, and the defect rate is 1 / 20;

Normal IC: Pin1 impedance to ground is infinite;

Abnormal IC: Pin1 impedance to ground is about 10M Ω;

  • 0
    TI__Guru**** 174286 points

    Hello Kevin,

    C33 on the output (pin 7) would give poor loop stability and the output might ring on transients or might even oscillate. The oscillation amplitude will be small (possibly unnoticed). What is the failure symptom? Even if the pin1 10M ohm leakage was real, that would not affect the circuit operation.

  • 0 in reply to Ron Michallick
    Expert 2925 points

    The samples sent to terminal customers after normal trial production (including function test) in the factory are 20 pcs in total,

    and 1 pcs of such defects are fed back, and the defect rate is 1 / 20.

    At present, LM258DR is invalid.

    Bad phenomenon: 0-10V cannot adjust the light;

    Bad analysis:

    1. Measure 0-10V output, the output voltage is fixed at about 19v; (the normal range is 0-10V)

    2. It is found that the  LM258DR is abnormal and crosses LM258DR with the normal board, and the bad phenomenon follows LM258DR;

  • 0 in reply to kevin.huang_FJXM
    TI__Guru**** 174286 points

    Kevin,

    When output was 19V what was the voltages on the other 7 pins? Based on the gross output error, my initial guess is ESD damage during handling.