Burns might remember the details (or Zach certainly would), but one of those parts was undersized for the RT-IHU and would cut out when we were transmitting with the ax5043. I think we had to back down the xmit power in order for the device not to reset.

Rich

On Thu, Jan 19, 2023 at 5:46 PM Jonathan Brandenburg via pacsat-dev < pacsat-dev@amsat.org> wrote:

In last week's meeting, I noted I had been looking at the schematics for Fox-1 and RT-IHU and found the circuits for the latchup protection and watchdog functions. I admit this might be basic to some, but I'm finding it fascinating! Anyway...

Since last week's meeting, I researched the parts used:

onsemi FPF2001 is a current limit switch used on both Fox-1 and half the RT-IHU. It's obsolete, replaced by onsemi's FPF2000. But the FPF2000 is listed as end-of-life. It's replacement part is the TI TPS22942.

MAX4995 is a current limit switch used on the other half of the. This part looks good for new designs.

For the watchdog functionality, both Fox-1 and RT-IHU use the STWD100NYWY3F chip. this parts looks good for new designs.

That's as far as I got. Next, I want to research the Fox-1 and RT-IHU designs to determine the thresholds of the current limit switches. In particular, I want to see if the TPS22942 is a suitable replacement, assuming we have the same current requirements.

That's where I'm at,

Jonathan

-- Jonathan Brandenburg Radio Amateur Satellite Corporation 1-214-213-1066

---

pacsat-dev mailing list -- pacsat-dev@amsat.org View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org To unsubscribe send an email to pacsat-dev-leave@amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org