We just received a new board with this HSC and I have a problem with it.
The bottom line is that Vout = 9V while Vcc is 12V due to the fact that the gate is not fully open.
I’m measuring on FLT_b = 2.8V, PGb = 2.9V, which mean there’s a power bad indication.
Please see the pic attached.
The yellow signal is the gate and the blue is the timer.
I have 3 problems there -
- The gate stops at 11.2V instead of reaching to ~26V as described in the DS.
- According to the DS, if Vtimer reaches 1.35V and (Vgate-Vcc) is below 5.9V, then Vgate should be grounded à I don’t see it here.
- The timer starts charging the capacitor long after Vgate reaches its max – something else is stopping the gate from rising.
in the DS figure 27 you clearly see those 2 signals rise almost at the same time.
I’m also adding my design below.
The average power on board is about 25W.
