LT8638S
Recommended for New Designs
The LT8638S synchronous step-down regulator features second generation Silent Switcher architecture designed to minimize EMI emissions while delivering...
Datasheet
LT8638S on Analog.com
Hello,
I measured on several different designs based on LT8638S a transient on output few ms after startup in no/light load conditions. During investigations, I noticed a transient on Vcomp, which seems to occur when SS reach around 1.7V.
The problem is not visible in LTspice.
Where does it come from? Is there a way to avoid such transient or is it intrinsic to the IC?
Here is my schematic
And here are the measurements (Vout in yellow, Vcomp in green)
Tnx
Dominique
Hello,
Here are all requested information
Input : 12V +/-10%
Output : 1.2V - 5A
The problem is observed in no load
1.2V LT8638.asc
Tnx
Hello,
It seems clearly related to Fsw mode. We are in FCM but it seems to be activated later after startup.
In term of output load, if we increase it, Vcomp will rise also, which will reduce the transient amplitude. Here is an exemple with 100mA at output
Is there a way to fix this without consuming more ?
Tnx
