Customer question:
Q: USB charge pump could output 100mA to VBUS, and there is short-circuit limitation (about 450mA). But we couldn't find the description on what's the action of TPS65950 after short-circuit. Will it just close the output?
A: Here are two cases for CP short circuit:
Incase of a Short circuit, there is NO direct impact on the system. Output of CP is NOT monitored and hence it will not go to power down mode. It has internal circuitry that will LIMIT the current to 450mA but there is no change to the system.
However, there may be indirect effects though:
1) Incase CP is used to provide supply to VUSB3P1 LDO, assuming there is a short circuit on CP, if its voltage goes low, it also means that VUSB3P1 LDO output will go LOW. Since LDO output is monitored, it will trigger short circuit protection for the LDO . This way system may be impacted.
2) Incase CP is used to provide supply to an external device ( via VBUS), now assuming there is a short circuit, if VBUS voltage goes below a certain threshold, OTG comparators will get this information and required interrupt will be sent to OMAP for further action.
Hence, although CP is NOT monitored directly as other LDOs/DCDCs are, there can be indirect effects as above. In both cases the system or the CP is safe.
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