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Need help to identify supervisor IC

Discussion in 'Electronic Components' started by Franc Zabkar, Oct 5, 2008.

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  1. Franc Zabkar

    Franc Zabkar Guest

    I'm trying to identify two 6-pin SMT supervisor ICs in a D-Link
    DSL-302G ADSL modem.

    They are U7 and U12, to the left of the Atmel EEPROM in this photo:

    The markings are ...

    The pinouts appear to be as follows

    U7-1 NC (?)
    2 ground
    3 RST* to GS8120 CPU pin 53, VIA VT6103 pin 48, JP2-3
    - pulled up to CPU Vcc by R51 (4K7)
    4 CPU Vcc
    5 NC (?)
    6 CPU Vcc

    U12-1 NC (?)
    2 ground
    3 RST* to GS8120 CPU pin 68
    - pulled up to CPU Vcc by R30 (4K7)
    4 <-- R65 (3K0) --> ground
    5 NC (?)
    6 <-- R66 (4K7) --> unregulated 12VDC from bridge rectifier

    I suspect that the reset output is open collector or open drain, as it
    is bussed to connector JP2 which is provided for EEPROM programming
    via an external jig. I'm guessing that the NC pins may be manual reset
    pins, and/or RC time constant pins.

    The CPU/DSP, GS8120, is from a Globespan Virata Viking chipset. Does
    anyone have a datasheet for this chip?

    - Franc Zabkar
  2. Eeyore

    Eeyore Guest

  3. Franc Zabkar

    Franc Zabkar Guest

  4. Franc Zabkar

    Franc Zabkar Guest

  5. Franc Zabkar

    Franc Zabkar Guest

    This is a similar PCB with U12 unpopulated:

    It shows that pins 4 & 6 are linked at the resistor pads, which
    suggests that the two resistors form a potential divider, and that U12
    lets the CPU know when the +12V input is low.

    - Franc Zabkar
  6. JW

    JW Guest

    I can't help you with identifying those parts, but with a few mods
    (removing R65 for one) I bet you could use a couple of LM3724IM5-4.63
  7. Franc Zabkar

    Franc Zabkar Guest

    Thanks, but I should have explained that I'm not trying to repair a
    fault. I'm just trying to add a manual reset switch with the least
    amount of effort. If the NC pins are internally debounced manual reset
    inputs, then all I have to do is to add the switch. Otherwise I plan
    to add a debounced reset input via JP2, without disturbing the PCB (my
    eyesight isn't as good as it used to be).

    - Franc Zabkar
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