ADP7183
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The ADP7183 is a complementary metal oxide semiconductor (CMOS), low dropout (LDO) linear regulator that operates from -2.0 V to -5.5 V and provides up...
Datasheet
ADP7183 on Analog.com
Hi,
since the adjustable type is currently not available, is it possible to add an external resistor to a fixed version to change the output voltage?
From information given in the datasheet it looks like it is allowed to add an external resistor in parallel to the internal ones to change the output voltage, but this is not explicitly stated. Also there is no simulation model available to confirm this in LTspice.
What I am planning for a prototype is to use the ADP7183ACPZN1.0-R7 and add a 70.6k resistor from VAFB to GND to get an output voltage of -4.5V. I am correct to assume the internal divider is 500k / 500k for R1 and R2? The external 70.6k resistor would make the divider R1=500k, R2=500k||70.6k=61.8k so the output Voltage is 0.5*(1+500k/61.8k)=4.55V.
Hi DamianS,
Based from its block diagram, those feedback resistor was placed inside of ADP7183. If we know the internal resistance value of R2, we may vary the output of those fixed ADP7183. Assume value would not be correct.
However, placing a potentiometer outside between VAFB and VA would help to predict the value of R1 thus giving you the desire output.
Regards,
Xian
