Tool/software:
Hi team,
Customer will use TLV76050 and wants to add large capacitor in output for MCU.
Once the input shut down, I recommended Schottky diode being parallels with LDO to prevent reverse current.
However, there is another concern that, does LDO consume current from Schottky to VIN like below?
I think that VIN will be Hi-Z when no input voltage, so consumed current is not so much. However, how to calculate it?
Best regards,
Hayashi
Hey Hayashi,
Generally, in this implementation, the assumption we take is that when input supply goes away, VIN is connected to ground and hence the output capacitor discharges to ground through Schottky diode.
But as you mentioned, if VIN node is in Hi-Z config, there is going to be a charge sharing mechanism between Cout and Cin. Due to which some kind of voltage can be developed on the VIN pin of the LDO as the current flow path that you mentioned can happen.
But as VIN is always lower than VOUT pin, Part will always be in dropout operation and there is going to be a current flow through LDO ground (quiescent current).
In the datasheet of TLV760 (Fig 3), IQ vs VIN is captured, where depending upon VIN level, the current flowing to ground can be roughly estimated.
Please review and let me know if further details are needed.
Regards,
Rohit Phogat
