[Oap-discuss] DC/DC switching power regulator

[Scott C. <rob...@gm...>]

Dafydd,

Aaron brought to my attention that the Texas Instruments DC/DC 1.5A
positive step-down integrated switching regulator 78ST105HC is shown as
"obsolte" by Mouser and Digikey.

The TI 78ST105HC is used on the HCM, SAM, and PMM PCBs.

TI-recommends TPS84250 as a replacement.
http://www.ti.com/product/tps84250
However, this, too, is being transitioned to LMZ3xxxx

The replacement would be here:
http://www.ti.com/lit/ds/symlink/lmz35003.pdf

The main concern I have is that it's a QFN (quad flat no leads) package.
The LMZ3 is especially challenging as the connections are on the bottom of
the chip.
Here is a manual QFN soldering example:
http://store.curiousinventor.com/guides/Surface_Mount_Soldering/QFN/

The LMZ3 output voltage and switching frequency are regulated by external
resistors (pages 13-15).  It has a power good pin that could signal the PIC
in the event that

Aaron found a few of the obsolete TI regulators on ebay.

Do you have any recommendations?

Thanks,
--scott