Vin = 20V, Vout=12V, L = 10uH, Rcurrent sense = 5mOhm, Cout=300uF, Iout - not meaning, 450kHz FPWM, SoftStart = 50ms, Hicuup Fault=60ms. EN pin- button
All values correspond to Exel Ref.des (LM25141-Q1 Quickstart Tool - revA2). Compensation Design - 6kHz is designed for real parameters.
With a connected load (0.1A small load and more), it does not turn on. At the midpoint Q1-Q2 we see one narrow pulse with a frequency of 450 kHz. No output voltage. Disconnect the load, connect the load - perfect, everything works.
What's the problem?
Thanks,
no load then LM25141 turn on
smal load (0.1A) then LM25141 turn on
Real ESR for calc Compensation des
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Tests.
- No load
Apply voltage -> Turn on EN pin.
The result is great. The output voltage is stable. Q1, Q2 commutation is correct, without overvoltage. We connect / disconnect the load on the included board - it works. All perfectly.
- We connect the load to the switched off board. We apply voltage, turn on the EN pin - one narrow pulse with a frequency of 450k.
We remove the load, connect the load - it works.