ADP1607 to supply ADAU1761

Document created by analog-archivist Employee on Feb 23, 2016
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I'd like to use the ADP1607 to supplying the ADAU1761 for a mobile audio
project (single cell).  For suppling by USB or external supply I inteded a LDO.
To avoid voltage drop I shoudn't use a diode for connecting Vout of the LDO to
the Vout of the ADP1607. Thats why I'm looking for a DC/DC stepup converter
with reverse current protection both the EN PIN is OFF or ON.

 

The ADP1607 has an internal high side P-FET. So there is a body diode
conducting from the switch node to Vout. The Vout pin is specified as abs max
rating from -0.3V to +3.6V independent of Vin. By definition boost regulators
prevent reverse current, since without a diode from switch node to Vout, the
output voltage could not get boosted up to higher values than Vin. The body
diode of the high side P-FET as shown in the block diagram on page 10 is
implemented regardless of the EN high or EN low.

If the Output of the ADP1607 is clamped by the LDO at an output voltage that is
lower that what the ADP1607 is set to with the feedback resistors, it will
deliver max power as it tries to bring the output voltage up to the ADP1607 set
voltage.
This would be a very risky configuration if you can’t guarantee that the LDO
output voltage will never fall below the ADP1607 set voltage.

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