TL783

Srivatsa,

What is the minimum load current and minimum input current?
I ask because TL783 has a high drop out voltage and a minimum load current (the feedback resistors can be part of the load)

Hi Ron Michallick,

Min Load current required is 50mA and max of up to 100mA. The input current capability of our source is 2A and even more.

Srivatsa,

Sorry, I meant to ask for minimum input voltage.

I suggest a R1 of 1.24k 1% and R2 of 90.9k.
This gives a feedback current near 1mA. Power dissipation in R2 is 91mW.

VOUT = R2/R1*Vref + Iadj * R2 = 73.31*1.25V + 83uA*90.9k = 99.17V (nominal).
Vref can be 1.2V to 1.3V. Iref can be 60uA to 110uA.

Vout is independent of VIN, if VIN-VOUT is greater then drop out voltage.

Hi Ron Michallick,

Thanks for the values. The minimum input voltage is 95VDC and the max would be 120V however I need a constant voltage output between 95 to 100V @ 100mA output.

Thanks and Regards

Srivatsa

Srivatsa,

The 95V input to 95V output disqualifies a LDO as a solution. 
A DC to DC converter will be needed unless the requirement for minimum VIN or VOUT be be changed.

Hi Ron Michallick,

I have the min operating value at 85V so the input range is 95 to 120 and the output can be from 185 to 100VDC.

Thanks and Regards

Srivatsa

Srivatsa,

In that case the TL783 can be used.