TPS7A83A: The difference between NFET LDO and PFET LDO

Charlie Xiao

Part Number: TPS7A83A

Hi BU team,

Fundamental Theory of PMOS Low-Dropout Voltage Regulators said that most LDOs are PFET structures. But why? As for me, NFET has lower ON resistance than PFET.

So what scenarios are NFET LDO and PFET LDO used for?

What are the advantages of PFET LDOs that make PFET LDOs more widely used than NFET LDOs? Thanks.

Regards，

Charlie

over 1 year ago

+1 John Schneider over 1 year ago

TI__Genius 12511 points

Hi Charlie,

Here is a link to another e2e post discussing the differences between the two architectures.

Primarily it is dependent upon the output voltages. NMOS generally performs better at low VOUT and PMOS generally performs better at higher VOUT's.

NMOS's do come with a non trivial drawback which is that they often require bias voltage rails, but since they are low input/output voltage operations, this means that a charge pump must be introduces which is a problem for noise and expense.

Regards,

John

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TPS7A83A: The difference between NFET LDO and PFET LDO