Helllo All,
I have new design of UCC2897a .
I am not able to get it to switch at all.As I have understood the documents, the condition is right for switching. I cannot see any reason why it should refuse to switch.Below are Voltages on the IC PINs.
Vin=22 VDC
Vrdel=2.5 V, Rdel= 10K
Vr-on=2.5 V Ron=121 K
Vr-off=2.5 V Roff=121 K
Vref = 5 V
Vr-slope = 1.4 usec OFF, 4.6 uSec ON, 0.4 - 2.2 V ramp during ON, Freq=160 KHz
Vfb = 5V
Vss/sd=2.8 V
Vaux=>10.8 V continuously
Vout=0.4 V
PVdd=Vdd= Max 12.7 V, Min 10.8 V
Vl-uv=3.2 V
Vov=0.2 V
Vcs=0 V
Rdel=10 K
Ron=Roff=121 K
Vss-sd=0.5 V - 2.8 V Triangular waveform, with the left leg period = 15 ms,Right leg period=11 ms, Total period = 26 ms. ( There is no Flat top at all. Only ramp up and ramp down. This seems to tell retry attemps and failure to see some necessary condition. But I cannot see which one could be that condition.
Any help to understand the situation will be of great help. Thanks in advance.
P Bhat
