I'm using an LV2862 to step down 22V to 3.3V, powering a MCU.
During initial MCU programming, the 3.3V rail may be supplied by the programming jig, while the rest of the device is unpowered.
This would back feed the LV2862 with 3.3V (there is a 1000uF capacitor on the buck input which could draw a considerable current). The SHDN pin is connected through an UVLO resistor divider, so the buck wouldn't turn on at this voltage. Is this back feeding dangerous?
In the datasheet the CB to SW voltage has an absolute minimum rating of -0.3V. In the above situation, wouldn't the CB to SW voltage be -3.3V, via the CB capacitor? Or are they connected together internally such that back feeding wouldn't cause such a voltage drop?
It's looking like I may have to add a series Schottky diode after the buck converter circuit, to avoid any of this back feeding. Is that correct, or is 3.3V back fed to the LV2862 harmless?
Thanks for your help.
