Primary (eg USB) and Auxillary (eg, Battery) Power Steering IC?

[sleemanj]

Short version: does anybody know of an IC that does something like the LTC4412, but which is closer to "jellybean level" pricing.

Long version: this seems like something that there should be ICs for, simply to handle disconnecting one DC power supply when another DC power supply becomes available (or vice-versa), classic example battery backup, but without any charging.

In it's most basic form, an ideal diode.

It just feels like this is a problem that should have been well and truly packaged into an IC (controlling a single FET).  And of course, it has, in the LTC4412/4414, but the pricing of this part is not very attractive, for what seems like it should be a really common thing.

[dannyf]

I am sure that you can make an ic for it but a simpler version would use a diode (a mosfet configured as a diode).

[sleemanj]

Yeah, it can be done discretely of course, this is what I came up with (ignoring specific parts, probably needs a cap, and it almost certainly has some stupid noob mistake that would stop it working).

But it just seems like something that should be out there in a ready-to-roll package.

[Frant]

We use the LTC4412 in a product and spent ages looking for alternatives. Basically it's as cheap as it gets for this sort of thing, and works very well. It's a non-trivial problem, hence the cost.

How about the TPS2115A?

[zapta]

How about the TPS2115A?

Looks good to me. Contains the power mosfets, not just the detection and drive, provides low resistance also both input (as opposed to a OR diode on one input) and less expensive.  Is there a catch?

[marshallh]

I've designed TPS2111APWR into some stuff. It works up to 1A, adjustable current limit set via resistor. Saved me from blowing up some boards due to manufacturing defects. Works just like you'd expect.
$0.98 @ 100.

[scott216]

I asked a similar question on the Arduino forum and ended using a mosfet and a couple schottky diodes.  Here's the link:
http://forum.arduino.cc//index.php?topic=185144.msg1371898#msg1371898

I used it to switch between power coming from my FTDI cable or USB cable.