I have an LM25576 regulating approximately 12 V down to 4 V. The LM26676 is a buck switching regulator and in my power supply it is rated to 2A. It has a soft start capacitor so that the output voltage comes up fairly slowly.
From that I am feeding a ZXCL300 to give me 3 V at a few mA.
The problem is that as I turn on the 12 V, the ZXCL300 sometimes goes up in smoke.
I've looked at the 4 V line with a scope and there don't seem to be any spikes, but I am not entirely sure. When I switch on the 12 V with a transistor there isn't a spike and I can just see the ramp controlled by the LM25576. There is a 100 uF capacitor on the output of the buck regulator, and a couple of ceramics as well.
Any ideas?
From that I am feeding a ZXCL300 to give me 3 V at a few mA.
The problem is that as I turn on the 12 V, the ZXCL300 sometimes goes up in smoke.
I've looked at the 4 V line with a scope and there don't seem to be any spikes, but I am not entirely sure. When I switch on the 12 V with a transistor there isn't a spike and I can just see the ramp controlled by the LM25576. There is a 100 uF capacitor on the output of the buck regulator, and a couple of ceramics as well.
Any ideas?