gate voltage (yellow) drain voltage (blue) pin3 signal (purple drain current (green)
What was the state of the STOP switch and the polarity of L2 when this scopeshot was taken? Gate voltage ref GND - too good (less than 50% duty cycle as expected). Pulses at pin 3 can decrease this duty cycle even down to 0%. Drain voltage ref GND - Enough to break down a 50V rated diode (D5). @ Lost_bro, help me to figure out what causes that little falling edge in the second half of the OFF period (? voltage across L2 relative to voltage across C11 ?). Pin3 voltage ref GND - Hmm, are those ±2V spikes an EMI artifact, Dirty ground (e.g. ground loop) or real steering pulses ? What is going on at pin 2 ? Drain current - Drain current does not mean much. L1 or L2 current is significant. input 14V @ 10A
That's too much. We need to get the feedback loop (pins 2, 15, 3) to work properly so it can decrease the MOSFET's duty cycle and decrease the current draw with it. The feedback loop is now negative so it is capable of accomplishing that. P.S. Please do not push this circuit to 14V 10A because sth will break. We should be striving for minimum current draw.
« Last Edit: 2014-04-17, 11:36:07 by verpies »
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