Question for your ADP2120

Question

Dear Sir/Madam, 
 I have a question for you. 
 As for your ADP2120 switching power device, 
 If there is no load on output side, does the input voltage appear to the output side directly? 
 This means that the p-ch FET is always ON, I think. 
 Please let me know your comment here. 
 Thanks Kaos

jespirit · Accepted Answer

Hi Kaos, 
 That is a possibility. Another possible reason though is that the feedback loop has been opened in your setup, due to poor solder, poor traces, etc. I'm referring to the connection between the output cap, going to the FB pin of the device. If you're using the adjustable version, there should be a resistor divider from the top of the output cap (Vout) going to FB pin. If you're using the fixed voltage version, then the FB pin should be directly connected to the top of the output cap. If by any chance that this connection has been opened, then Vout will rail to the input voltage, which is similar to what you are seeing. 
 Best regards, 
 Jess

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Question for your ADP2120