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Anyone here still messing with TI's ISR's

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  • Anyone here still messing with TI's ISR's

    I'm playing with my p.s. again. If you've been around here a while someone came on telling about a new p.s. they were designing that was extremly efficient and small and required no heatsinks based on TI's ISR's. I bought a 3.3v out and a 5V out from digikey and requested the 12v out from ti as digi didn't carry it. Real small parts and only take a couple caps for in and out. I built a small p.s. on a radio shack protoboard and used a linear for the 5vsb and 4049 for the power good like a sproggy. It didn't work quite right so I had to hardware the atx power and put a mechanical switch on the input. Anyway I narrowed my problem down to the standyby input on the ISR's. My mb powers up fine the first time then powers off, but then the isr's stay off untill power is removed completely. I don't know why they are hanging there. Anyone else tried them?

    Found the thread, Kaboom was the guy. Is he still around? My thoughts are to drive each isr's standyby input seperatly using the extra 4049 gates. maybe that will work.

  • #2
    yeah... i remember this idea too... seemed like a good plan.

    but right after Kaboom made the first prototype, he seemed to disappear. said he would be giving some updates after the testing and pricing were completed.

    perhaps the 12 volt PSU mafia picked him up and "dealt with him"

    ~mike
    Single Member of the "1000 Post and No MP3 Car" Club
    PROJECT ON INDEFINATE HOLD... BOUGHT A HOUSE
    2000 Cavalier Z24 [###-------] Only 30% Done ... Still

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    • #3
      I think I found my problem. I am using a 4049 which is a low power cmos for the standby line driver. One of the ISR spec sheets says it needs do be driven by an open collector ttl circuit. SO I have ordered a 7406 from digikey and will be trying it early next week when I get my order. I think that was my prob, I was overloading the output of the 4049 and it was shutting down. So I think I'm real close to getting a fully working system. I have my own web space now so I will be drawing up schematics of the working system and posting them. So far every part is available from digikey except for one of the ISR's that I had to request a sample (the 12v 1.5A one). They are not cheap, almost $30 each though.

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      • #4
        Grrrr, ISR's say dedicated gate. So I need three gates (1/2 of a 7406) to make it work. Even then it still loads the 7406 down enough that it fails. Might just use three transistors or a relay.

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        • #5
          Got any schematics?

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          • #6
            Not yet, basicallt take the app notes from ti and combine the three with the power good from a sproggy and you have it. I plan to draw it up soon but I still haven't gotten it working and I have to take a trip tomorrow!

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            • #7
              what isr's are u using? ive been paging through the TI webpage, and i cant seem to locate the appropriate parts.

              ~mike
              Single Member of the "1000 Post and No MP3 Car" Club
              PROJECT ON INDEFINATE HOLD... BOUGHT A HOUSE
              2000 Cavalier Z24 [###-------] Only 30% Done ... Still

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              • #8
                PT6621 for the 5v and 3.3v and pt5071 for the 12v

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                • #9
                  Got any schematics?
                  IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

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                  • #10
                    I plan to draw up schematics soon, but they are basically the same as the ones from the TI datasheets.

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                    • #11
                      I just finished my ISR power supply. Now managed to get my entire system down to 8"x6"x2" with this (even though the new ISR based power supply is larger). Boosted the overall efficiency of the overall system to 84% (draws just over 2 amps), so it keeps the heat down.

                      Is anyone else running a PT6625 for 5v? I've noticed that one of the chips on the ISR module runs quite hot. It's an 8 pin surface mount chip in the top left of the device, and it gets too hot to touch quite quickly after switching on. The ISR is heatsinked and the rest of the ISR and the heatsink runs cool. Seems to run fine with it hot, but was just wondering if I should be worried.

                      For the standby pin, I just tied the two ISR standby pins together, and used a potential divider and protection zener to keep the standby signal voltage in a good range, for an power on input between 5 and 12v. (4k7 pull down, 15k to power on signal, 4v7 protection zener between ground and standby pin). Seems to work just fine.


                      Rob
                      Old Systems retired due to new car
                      New system at design/prototype stage on BeagleBoard.

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