Alternatives to ONSemi NCP303LSN09?

[sjalloq]

The XMOS reference designs use the ONSemi NCP303LSN09 0V9 voltage detector as a power on reset controller for the L1. However, it's impossible to get hold of. Has anyone managed to find any alternatives?

I've also been looking at 1V0 regulators with a Power Good output. TI has a number of parts but they're all quite expensive compared to the ONSemi trio of 3V3, 1V0 regs and 0V9 voltage detector.

Cheers.

[bearcat]

If you look at the prior rev of the design, they did not have that part. I simply added an RC delay to the enable line on the NPC1529D for the 1v supply. This slows the startup of the 1V supply over the 3.3V supply. PM me if you want the values I used. Much simpler and cheaper, but not as robust for power glitches and a little slower on startup. You would have to coordinate your reset also. Seems good in my limited testing so far, but make your own choices as this does not follow the current reference design.

[sjalloq]

Thanks but the NCP303 is used for power on reset control. I've actually decided to use a TI TPS65001 which has a DC/DC converter, two LDO's and a voltage supervisor in one package. Buy 10 and it comes to the same price as the 4 ONSemi parts. Nice.

[bearcat]

Be sure to review the design checklist from XMOS. They indicate that the 3.3V rail needs to come up and be stable before the 1V rail. More details in the checklist.

[leon_heller]

This is the relevant document:

http://www.xmos.com/kbase/index.php?Vie ... EntryID=28

[sjalloq]

Yeah, found that already thanks. Along with the nice addition to the USB Audio design guide that lets you know that certain ports are used internally in ULPI mode. At least I hadn't assembled my boards before finding that out.

Cheers for the heads up anyway.

[kster59]

I have a reel of 3000 for the NCP303LSN09T1G but wait times are now 26 weeks on this part!

Are there any 100% substitutes?

[Corin]

The Rohm BU4209G is a pin and footprint compatible replacement part, but unfortunately that is also proving hard to source. There seems to be a general shortage of 0V9 voltage supervisors at the moment.

Regards,
Corin

[kster59]

Hmm I can't find that ROHM part either.

26 weeks is pretty annoying and can break a good product.

Even if you can find 10 pieces that's not enough for a production order.

Does XMOS have another suggestion or reference design that doesn't use this part?

Might be easier to redesign after my reel runs out.

[kster59]

What about NCP303LSN10T1G ? These are instock.

Seems the same but monitors 1V instead of .9V.

Shouldn't the monitored voltage be 1.0V anyway?

Anyone see any problems with a direct substitute?

I ordered a few samples from mouser to check.