- pacsat-dev - mailman.amsat.org

Re: Latchup Protection and Watchdog Parts
by Bob Stricklin 25 Jan '23

25 Jan '23

Jonathan, This is a complicated issue that will require some time to study. First the Excel spread sheet I sent is a early look at currents needed. Since I put that together some of the parts have changed and some have been added. I am sure we have a power issue but taking the position of just trying to get everything we want done then we can back down on capability and reduce power later. There is not a limit or budget on power at this time. Each time you add one of these current monitors to the design you introduce another part that can fail due to latch-up and other reasons. The action taken for each monitor added may be different. Latch-ups are possible from radiation exposure. These can be single event or they can result in a hard failure of a part. When there is an event and high current the plan may be to power down and wait for a period of time and then try to restart. If it is the processor with an issue then you are restarting everything if it is a sub circuit then you may be able to do a quick recycle. There are different types of current monitors to help you with your action plan. It may also be necessary to build a subcircuit to get the results needed. It is likely that we never see this happen but if it does happen we will want to capture the event in some way. If a problem is happening in orbit in a particular die/circuit we may be able to work around the problem. If it is the processor that is more difficult to capture events. The processor and memory will have larger die size and more gates so more likely that if we do have any events these will be the parts with a problem. I worked on optical ICs and since these were exposed to light we had to be careful not create an issue with latch-up. When a new design comes out of wafer fab it is one of the early test you do to see if you have issues. If you find a problem you have try and fix it by changing the die layout, adding more metal or modify the circuit. When a device is “radiation harden” this should also be done and hopefully the TMS570 had this done. Still could fail with radiation though. These are some of my thoughts. Bob On Jan 24, 2023, at 4:54 PM, Jonathan Brandenburg (KF5IDY) via pacsat-dev <pacsat-dev(a)amsat.org<mailto:pacsat-dev@amsat.org>> wrote: Now that you mention it, not my forté either! I was working in the abstract without really thinking about what a latchup actually results in… I think I was just assuming “super high” current without any real idea of what that really means. I conceptually like the idea of each “subsystem” having its own current limiter that is tuned to that particular device. Takes a bit of real estate but these are small chips. Jonathan Sent from my iPad On Jan 24, 2023, at 5:43 PM, Burns Fisher (AMSAT) <wb1fj(a)fisher.cc<mailto:wb1fj@fisher.cc>> wrote: Not really my forté but I’d worry that a higher current load switch for two devices would allow a higher current due to a SEU on a single device. Too much current and device fails before the load switch cuts it off? On Wed, Jan 25, 2023 at 11:37 AM Jonathan Brandenburg via pacsat-dev <pacsat-dev(a)amsat.org<mailto:pacsat-dev@amsat.org>> wrote: On 1/19/23 17:40, Rich Gopstein via pacsat-dev wrote: > 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. > > It didn't take a whole lot of research for me to figure this one out. The FPF2001 used on the Fox boards has a fixed current limit of 50mA. I can see that could be sufficient for the Fox IHU since it uses a low power processor and doesn't have transceivers or the power amplifier. The direct replacement part for the FPF2001 is the TI TPS22942 and it appears to be pin compatible with a fixed limit of 100mA. Would a 100mA be a problem on Fox? I wouldn't think it would cause failure in the 10ms it takes to blank the current but I make that statement without any real basis. Perhaps the 40mA limit of the TI TPS22942 would be sufficient. Anyway, back to PACSAT... With the higher current capacity of the MAX4995, adjustable between 0 and 600 mA, it could be the better choice than the fixed TI TPS22942. I'm not aware of flight experience with either so I tend to look to the MAX4995 with the adjustable and higher current limits. With this decision and looking at the approach employed on the RT-IHU I could see the following: 1 - The TMS570 and associated circuitry get their own MAX4995. As a first order pass contained in Bob Stricklin's spreadsheet the current requirement is 458.3mA, within the MAX4995's capabilities. If we want to further "derate" we could put the TMS570 on one MAX4995 and have a second MAX4995 for the peripherals. 2 - All five AX5043's require 100mA. Would we want to have 2 of the AX5043's on one MAX4995 and the remaining AX5043's on the other MAX4995 in case one MAX4995 fails prematurely? The value of this would depend on all the AX5043's being equivalent in function (i.e., all could be used for command and/or telemetry). This only takes care of this particular failure mode and still leaves a lot of other failure modes in which an early MAX4995 death would leave the system INOP so there may be limited value in using two MAX4995's for the AX5043's. 3 - Finally, the amplifier/pre-amp is an additional 415mA. Again, if we want to "derate" we could put the power amp on it's own MAX4995. It looks like we need a minimum of 3 MAX4995's and a possible max of 6 MAX4995's. (With further analysis, we might need one more to split the 1.2V and 3.3V power lines to the TMS570.) The MAX4995 are small chips so don't require a lot of real estate. We can discuss the risk vs reward of using more MAX4995's at some point. I welcome comments Jonathan -- Jonathan Brandenburg Radio Amateur Satellite Corporation 1-214-213-1066 ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org<mailto:pacsat-dev@amsat.org> View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org<https://url.emailprotection.link/?buUg7YY4HZLXKo6ZKNudC8bRTBdOsBlAV5C9rq-aq…> To unsubscribe send an email to pacsat-dev-leave(a)amsat.org<mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org<https://url.emailprotection.link/?bO71JCUf8Kb7txAlIoAarNqcIdQhyb8VQQIN4j0Gi…> -- 73, Burns Fisher, WB1FJ AMSAT(R) Engineering -- Flight Software ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org<mailto: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(a)amsat.org<mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org

1 0

Re: Latchup Protection and Watchdog Parts
by Burns Fisher (AMSAT) 25 Jan '23

25 Jan '23

Not really my forté but I’d worry that a higher current load switch for two devices would allow a higher current due to a SEU on a single device. Too much current and device fails before the load switch cuts it off? On Wed, Jan 25, 2023 at 11:37 AM Jonathan Brandenburg via pacsat-dev < pacsat-dev(a)amsat.org> wrote: > On 1/19/23 17:40, Rich Gopstein via pacsat-dev wrote: > > 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. > > > > > It didn't take a whole lot of research for me to figure this one out. > The FPF2001 used on the Fox boards has a fixed current limit of 50mA. I > can see that could be sufficient for the Fox IHU since it uses a low > power processor and doesn't have transceivers or the power amplifier. > The direct replacement part for the FPF2001 is the TI TPS22942 and it > appears to be pin compatible with a fixed limit of 100mA. Would a 100mA > be a problem on Fox? I wouldn't think it would cause failure in the 10ms > it takes to blank the current but I make that statement without any real > basis. Perhaps the 40mA limit of the TI TPS22942 would be sufficient. > > Anyway, back to PACSAT... > > With the higher current capacity of the MAX4995, adjustable between 0 > and 600 mA, it could be the better choice than the fixed TI TPS22942. > I'm not aware of flight experience with either so I tend to look to the > MAX4995 with the adjustable and higher current limits. With this > decision and looking at the approach employed on the RT-IHU I could see > the following: > > 1 - The TMS570 and associated circuitry get their own MAX4995. As a > first order pass contained in Bob Stricklin's spreadsheet the current > requirement is 458.3mA, within the MAX4995's capabilities. If we want to > further "derate" we could put the TMS570 on one MAX4995 and have a > second MAX4995 for the peripherals. > > 2 - All five AX5043's require 100mA. Would we want to have 2 of the > AX5043's on one MAX4995 and the remaining AX5043's on the other MAX4995 > in case one MAX4995 fails prematurely? The value of this would depend on > all the AX5043's being equivalent in function (i.e., all could be used > for command and/or telemetry). This only takes care of this particular > failure mode and still leaves a lot of other failure modes in which an > early MAX4995 death would leave the system INOP so there may be limited > value in using two MAX4995's for the AX5043's. > > 3 - Finally, the amplifier/pre-amp is an additional 415mA. Again, if we > want to "derate" we could put the power amp on it's own MAX4995. > > > It looks like we need a minimum of 3 MAX4995's and a possible max of 6 > MAX4995's. (With further analysis, we might need one more to split the > 1.2V and 3.3V power lines to the TMS570.) The MAX4995 are small chips so > don't require a lot of real estate. We can discuss the risk vs reward of > using more MAX4995's at some point. > > I welcome comments > > Jonathan > > > -- > Jonathan Brandenburg > Radio Amateur Satellite Corporation > 1-214-213-1066 > > > ----------------------------------------------------------- > > pacsat-dev mailing list -- pacsat-dev(a)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(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences at > https://mailman.amsat.org > -- 73, Burns Fisher, WB1FJ *AMSAT(R) Engineering -- Flight Software*

2 1

Re: Latchup Protection and Watchdog Parts
by Jonathan Brandenburg 25 Jan '23

25 Jan '23

On 1/19/23 17:40, Rich Gopstein via pacsat-dev wrote: > 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. > > It didn't take a whole lot of research for me to figure this one out. The FPF2001 used on the Fox boards has a fixed current limit of 50mA. I can see that could be sufficient for the Fox IHU since it uses a low power processor and doesn't have transceivers or the power amplifier. The direct replacement part for the FPF2001 is the TI TPS22942 and it appears to be pin compatible with a fixed limit of 100mA. Would a 100mA be a problem on Fox? I wouldn't think it would cause failure in the 10ms it takes to blank the current but I make that statement without any real basis. Perhaps the 40mA limit of the TI TPS22942 would be sufficient. Anyway, back to PACSAT... With the higher current capacity of the MAX4995, adjustable between 0 and 600 mA, it could be the better choice than the fixed TI TPS22942. I'm not aware of flight experience with either so I tend to look to the MAX4995 with the adjustable and higher current limits. With this decision and looking at the approach employed on the RT-IHU I could see the following: 1 - The TMS570 and associated circuitry get their own MAX4995. As a first order pass contained in Bob Stricklin's spreadsheet the current requirement is 458.3mA, within the MAX4995's capabilities. If we want to further "derate" we could put the TMS570 on one MAX4995 and have a second MAX4995 for the peripherals. 2 - All five AX5043's require 100mA. Would we want to have 2 of the AX5043's on one MAX4995 and the remaining AX5043's on the other MAX4995 in case one MAX4995 fails prematurely? The value of this would depend on all the AX5043's being equivalent in function (i.e., all could be used for command and/or telemetry). This only takes care of this particular failure mode and still leaves a lot of other failure modes in which an early MAX4995 death would leave the system INOP so there may be limited value in using two MAX4995's for the AX5043's. 3 - Finally, the amplifier/pre-amp is an additional 415mA. Again, if we want to "derate" we could put the power amp on it's own MAX4995. It looks like we need a minimum of 3 MAX4995's and a possible max of 6 MAX4995's. (With further analysis, we might need one more to split the 1.2V and 3.3V power lines to the TMS570.) The MAX4995 are small chips so don't require a lot of real estate. We can discuss the risk vs reward of using more MAX4995's at some point. I welcome comments Jonathan -- Jonathan Brandenburg Radio Amateur Satellite Corporation 1-214-213-1066

1 0

PACSAT - AO-16
by Jim McCullers 24 Jan '23

24 Jan '23

At our development meeting last Thursday night one of the discussed items were the uplink frequencies of the original PACSAT. Curiosity over the weekend lead to a bit of online research that produced a few QST articles from the time period revealing details on the original PACSAT. PACSAT was AO-16 launched 33 years ago on January 22, 1990 along with an almost twin LUSAT (OSCAR-19) built by AMSAT Argentina. They were launched into sun synchronous orbit from the ESA facility in French Guiana with an altitude of 800km. Both were a new generation of Microsats measuring 230x230x213mm. AO-16 received on 2-meters at 145.9, 145.92, 145.94 and 145.96 mhz and transmitted on 437.050 with 4 watts maximum. LUSAT received on 2-meters at 145.84, 145.86, 145.88 and 145.90 mhz and transmitted on 437.125 with 4 watts maximum with a backup transmitter at 437.150. The frequencies vary by article probably reflecting changing configurations and the above were taken from a post launch article. Power output was variable by command and on 70cm achieved 65% efficiency. Uplink was FM, 1200 BPS Manchester encoded FSK and downlink was 1200 bps RC-BPSK SSB. Storage space was 4mb RAM. Interestingly, one QST article it list the designers of the command module and one call is familiar, N5BRG. All questions are now to you Bob! 73 Jim McCullers WA4CWI

1 0

Re: Latchup Protection and Watchdog Parts
by Rich Gopstein 20 Jan '23

20 Jan '23

Good question... Maybe it was just during development you need to disable it in order to successfully flash new code since nothing would be resetting the wd? I know on my board, the jumper is always in place so I don't know that we've tested the hw wd. Btw, the tms570 has a software watchdog which we have code for and we have tested. I also vaguely recall a conversation about the timing of the hw wd. I don't remember if it was the wd on the 1.1 board or the 1.2 board, but Zach had proposed a chip with a maximum timeout of something pretty short - well under a second. I was concerned that if something went south, the wd chip would continuously power cycle the processor multiple times a second. These conversations were from a while ago and I likely have the details wrong. On Fri, Jan 20, 2023, 8:18 AM Jonathan Brandenburg via pacsat-dev < pacsat-dev(a)amsat.org> wrote: > This I didn't know! Does anybody on the list know why the hardware > watchdog wasn't working as expected on the RT-IHU? > > Jonathan > On 1/19/23 17:43, Rich Gopstein wrote: > > And - as long as I'm thinking about it, we had to disable the hardware > watchdog on the RT-IHU to get it to run. I don't recall if that changed, > but if you get some RT-IHU boards, you might need to jumper the hardware WD > disable. > > Rich > > > On Thu, Jan 19, 2023 at 6:40 PM Rich Gopstein via pacsat-dev < > pacsat-dev(a)amsat.org> wrote: > >> 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(a)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(a)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(a)amsat.org >>> Manage all of your AMSAT-NA mailing list preferences at >>> https://mailman.amsat.org >>> >> >> ----------------------------------------------------------- >> >> pacsat-dev mailing list -- pacsat-dev(a)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(a)amsat.org >> Manage all of your AMSAT-NA mailing list preferences at >> https://mailman.amsat.org >> > -- > Jonathan Brandenburg > Radio Amateur Satellite Corporation > 1-214-213-1066 > > > ----------------------------------------------------------- > > pacsat-dev mailing list -- pacsat-dev(a)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(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences at > https://mailman.amsat.org >

1 0

Re: Latchup Protection and Watchdog Parts
by Bob Stricklin 20 Jan '23

20 Jan '23

Jonathan, Attached is an Excel file I have worked on for PacSat power needs. Bob On Jan 20, 2023, at 7:17 AM, Jonathan Brandenburg via pacsat-dev <pacsat-dev(a)amsat.org<mailto:pacsat-dev@amsat.org>> wrote: I seem to remember that, too. As such, we may need to look at other parts or different versions of the same parts. That depends, obviously on the maximum current draw expected during normal operation. Does anybody on this list know if we have that information for the AX5043 chain? Jonathan On 1/19/23 17:40, Rich Gopstein via pacsat-dev wrote: 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(a)amsat.org<mailto: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(a)amsat.org<mailto:pacsat-dev@amsat.org> View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org<https://url.emailprotection.link/?buUg7YY4HZLXKo6ZKNudC8bRTBdOsBlAV5C9rq-aq…> To unsubscribe send an email to pacsat-dev-leave(a)amsat.org<mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org<https://url.emailprotection.link/?bO71JCUf8Kb7txAlIoAarNqcIdQhyb8VQQIN4j0Gi…> ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org<mailto:pacsat-dev@amsat.org> View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org<https://url.emailprotection.link/?buUg7YY4HZLXKo6ZKNudC8bRTBdOsBlAV5C9rq-aq…> To unsubscribe send an email to pacsat-dev-leave(a)amsat.org<mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org<https://url.emailprotection.link/?bO71JCUf8Kb7txAlIoAarNqcIdQhyb8VQQIN4j0Gi…> -- Jonathan Brandenburg Radio Amateur Satellite Corporation 1-214-213-1066 ----------------------------------------------------------- pacsat-dev mailing list -- pacsat-dev(a)amsat.org<mailto: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(a)amsat.org<mailto:pacsat-dev-leave@amsat.org> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org

1 0

Re: Latchup Protection and Watchdog Parts
by Rich Gopstein 20 Jan '23

20 Jan '23

And - as long as I'm thinking about it, we had to disable the hardware watchdog on the RT-IHU to get it to run. I don't recall if that changed, but if you get some RT-IHU boards, you might need to jumper the hardware WD disable. Rich On Thu, Jan 19, 2023 at 6:40 PM Rich Gopstein via pacsat-dev < pacsat-dev(a)amsat.org> wrote: > 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(a)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(a)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(a)amsat.org >> Manage all of your AMSAT-NA mailing list preferences at >> https://mailman.amsat.org >> > > ----------------------------------------------------------- > > pacsat-dev mailing list -- pacsat-dev(a)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(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences at > https://mailman.amsat.org >

2 1

Re: Latchup Protection and Watchdog Parts
by Jonathan Brandenburg 20 Jan '23

20 Jan '23

I seem to remember that, too. As such, we may need to look at other parts or different versions of the same parts. That depends, obviously on the maximum current draw expected during normal operation. Does anybody on this list know if we have that information for the AX5043 chain? Jonathan On 1/19/23 17:40, Rich Gopstein via pacsat-dev wrote: > 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(a)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(a)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(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences at > https://mailman.amsat.org > > > ----------------------------------------------------------- > > pacsat-dev mailing list --pacsat-dev(a)amsat.org > View archives of this mailing list athttps://mailman.amsat.org/hyperkitty/list/pacsat-dev@amsat.org > To unsubscribe send an email topacsat-dev-leave(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences athttps://mailman.amsat.org -- Jonathan Brandenburg Radio Amateur Satellite Corporation 1-214-213-1066

1 0

Re: Latchup Protection and Watchdog Parts
by Rich Gopstein 20 Jan '23

20 Jan '23

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(a)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(a)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(a)amsat.org > Manage all of your AMSAT-NA mailing list preferences at > https://mailman.amsat.org >

1 0

Latchup Protection and Watchdog Parts
by Jonathan Brandenburg 20 Jan '23

20 Jan '23

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

1 0