Current Schottky diode between BATT and VDD4P2

[davidrabe]

The IMX28AEC Technical Data PDF says that "Application should include a Schottky diode between BATT and VDD4P2", but it didn't mention any current rating.

In Figure 8 of the AN4199 AppNote the diode is also shown. Although the MBR120VLSFT1G has a maximum rated current of 1A, I think that the diode is only needed for biasing the internal VDD4P2 circuit. Thus, the current would be theoretically negligible.

Does anybody know something more detailed about it?

[igorpadykov · Accepted solution]

Hi David, you are right diode is used for making voltages close

between BATT and VDD4P2, however another purpose - to provide

fast switching when software configures transition power supply from

battery to VDD4P2 (and vice versa). In later case diode should be powerful

enough to endure current spikes. So 1A is such kind of compromise.

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