Hi!
I'm working on a design using TPS92640 to drive a 32v 3A led block.
PWM frequency is ~1kHz
Psu that I'm using has output voltage of 42V.
So the design parameters I chose are:
Switching frequency:~600kHz
Turn on voltage: 37V
Output voltage protection level: 33V
Output current : 3A
The schematic is the same as in datasheet with the following values:
Ron=22k
Con=1n
Rvout1=270k
Rvout2=22k
Rcs= 5mOHM
Riadj1=22k
Riadj2=22k (Viadj=1,515V)
L=68uH
Rhg=Rlg=10OHM
Rf=470OHM
Rudim1=10k
Rudim2=360OHM
Rudim3=4,7k
Fets are SIS890 (100V, 8,8A)
The problem is, that when I look the waveform of the current with a scope and a current probe then
I see a 10A current spike. It seems that the current regulator is unable to switch off the fets during
this period when the current is rising. What can cause this?
With best regards,
Marek
