my customer is currently working on a project and he has some questions regarding the TPS78001 (see block diagram below).
His MCU would need to be powered either with 2V or 2.9V depending on which mode the MCU is currently working in and which peripherals (eMMC...) are ON. in other to generated the 2V and 2.9V from the battery (which voltage can vary between 2 - 4.5V) he connected the outputs of the two TPS78001 together (one with a Vout = 2V and the other with Vout = 2.9V). his questions are the following:
1. What will happen with the first LDO (with Vout = 2V ) when its ouput sees the 2.9V voltage coming from the second LDO (back-driving)? how high could the back-driving current be for the first TPS78001?
2. What happens with the second LDO (Vout = 2.9V) when it is disabled, but its output sees 2V coming from the first LDO's (Vout = 2V) output? How big could the back-driving current (reverse current) be in this case. Please see system block diagram below.