designing bench power supply.

[superwester]

Hello all,

im designing (implementing?) a diy variable power supply around the lm338. inspired by dave's usupply but taking my own direction.

that linear regulator has a minimum worst case load of 5mA according to the datasheet, so i was thinking of a solution hopefully not recurring to a current source ic and keep it discrete.

i ended up with this bjt current source http://tinyurl.com/y8nctaop the 5v will be fixed (maybe 3.3v later on)

is this a good enough solution?

any draw backs that im missing of?

thank you in advance.

[rdl]

The link does not work for me. However the LM338 is basically a higher current version of the LM317 and the minimum load requirement is usually taken care of by properly sizing the upper resistor in the divider which sets the output voltage (R1 in the diagram below).

[superwester]

sorry for the lateness.

Im aiming to drive the adj pin directly from a MCU, so i wont have that resistor to fix the problem