I'm guessing I'm missing the obvious here. I'm trying to build a discrete negative LDO using a NFET for the pass element. I'm basing it on the internal structure of the UCC284-5 seen here.
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I've tried inverting the output of the opamp with a BJT but its not regulating. The positive input to the opamp is tied to V4 which is a -
2.5V reference, feedback is negative. The opamp is supplied with
-18Vdc and +5Vdc. My pass element needs to regulate down to 500mV in/out differential.
Feeble attempt at a negative LDO schematic:
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