Hi,
We are having some trouble with a design that uses ADP5303-1. When toggling the MODE pin high, to put the converter into PWM mode, we occasionally see a fault condition where the output voltage collapses, and oscillates between about 0.8 and 1.1 V.
The below capture also shows the switching node (in blue), plus Vin (yellow), Vout (pink) and Vmode (green):
If we observe the output current (measured across a 0.1 Ohm shunt directly after the output capacitor), we can see the when the fault occurs, a large current flows back into the converter, after which the cyclic behaviour kicks in and the output oscillates. In the below capture, yellow is output current, and blue is voltage on the mode pin. Note that once the output begins to oscillate, the mode pin voltage follows the output voltage.
In our design the mode pin is pulled low with a resistor, but can also be pulled high by a microcontroller (via an inverter and buffer). All of this circuitry is powered by the output of the ADP5303, and so is not operating correctly once the system falls over.
If we swap the part out with ADP5303-2, with NO active discharge, the problem goes away entirely.
Could this be a fault in the way that we are using the pin?
Thanks.
