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LM5145: Ericsson LM5145 issues

Tommy Mao
Prodigy 70 points
Part Number: LM5145


Hi experts,

Ericsson has questions about  of LM5145.

 

May I ask what was the output overvoltage characteristic of LM5145? There is no explanation on the datasheet.

The following waveform, why did the low-side switch conduction for so long? The frequency is not a switching frequency.

CH3: LM5145 buck converter low-side switch GATE

CH5: LM5145 buck converter output voltage

The test conditions are as follows:

The Buck output port voltage has caused voltage overshoot due to the connection of the high-voltage capacitor.

 

Thank you!

Best regards,

Tommy Mao

  • 0
    TI__Mastermind 22302 points

    Tommy,

    Is that the LO waveform?

    Do you have the VOUT ripple waveform?

    It looks like the VOUT was overcharged and LO was turning on to discharge VOUT.

    See load transient figure 9-13 in the datasheet.Also see figure 9-1 in the datasheet.

    When a load current is removed, the output voltage will jump up and the inductor current must down-slope (LO on) until the inductor current is at the new output current.

    Hope this helps,

    -Orlando