Hi Expert,
Customer is using TPS7A4901 on their design. the input voltage is 24V and output voltage is 15V, output current is lower than 100mA in normal operation condition. Besides the 10uF output capacitor, another 100uF is added at the output. The customer found several failure chips. We found different phenomenon on these failure chips. For #1, #2, the ref voltage is obviously abnormal. For #3 and #4, the ref voltage looks OK but it couldn't start up successfully. Could you share your comment on in what condition will the customer get wrong voltage on the reference pin? And what may cause the device not be able to start up successfully?
#1: no output, the voltage on pin 6 is 7.5V
#2: no output , the voltage on pin 6 is 11V
#3: output voltage start up successfully and then drop down to zero, pin 6 voltage is 1.15V
#4: output voltage start up successfully and then drop down to zero, pin 6 voltage is 1.15V
Schematic:
Start up current in no load condition: