Hi,
I need to go from Vin={18 V to 24 V} down to Vout=17 V with a linear regulator. Iout is 60 mA. The LM317 and similar ones seem to need around 3 V input-to-output to provide good regulation, which is too much for me. I only have 1 V available. Does anyone know of a good smd part for this? Of course, I already count on having to use resistors to set the output voltage.
Thanks in advance,
You'll need a low dropout regulator (LDO). check the usual suspects web sites (National, TI, Linear, Maxim, Zetec, On Semi, Fairchild, ST to name but a few).
Most give parametric search
You'll need Vin (max) > 26V (have some headroom), Vo-Vi
Thank you. I know what I'm looking for, and how it is called. I just wanted to know if someone is already using a suitable part that can recommend to me, especially one that can be easily obtained through distributors like Farnell, DigiKey, Amidata...
Ideally, it should be one with a PMOS pass transistor and a very low quiescent current (100 uA max). So far, not much luck with Farnell.
Best,
lp2951 or lp2950 from national should fit the bill, dil and soic versions available from farnell
National's page for this device at:
Cheers
PeteS
Thanks again to both of you. The ground pin current (approx 3 mA @ 60 mA) kills me. That's due to the PNP. I have to connect around 200 units in parallel, hanging on a 24 V bus, and I'm trying to minimize the losses. I must say, I'm quite amazed that I cannot find one with a PMOS pass transistor that works at these voltage levels.
Best,
Now I can be saying the biggest bull***t of my life:
what about the use of the schematic on the national page with the added pass mosfet ? you should be able to lowering the ground current at desidered level augmenting the 2K resistor on OUT pin
a bit of overkill, the IC and an external MOS, but if you don't have other solutions ....
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