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Problems when starting UCD9222 with UCD9090

Asko Oinonen
Prodigy 110 points
Other Parts Discussed in Thread: UCD9222, UCD74111, UCD9090

Hi,

I have difficulties turning UCD9222 controlled powers ON.

I'm using UCD9222 and two UCD74111's to power two TMS320C6678s. I also have UCD9090 power manager to phase power and clocks to DSPs.

I can program both UCD9090 and UCD9222 with Fusion software (version 2.0.120). I use enable signals (individual signals for ENA1 and ENA2) from UCD9090 to turn UCD9222 halves ON.

I can turn UCD9222 powers ON from Fusion sw, when I select on/off config "Control pin only". Fusion sw controls PMBUS_CNTRL pin and UCD9090 controls ENAx pins. There is an AND function between them i.e. both CNTRL and ENAx needs to be high to turn ON the power.

I have to toggle CNTRL signal OFF and ON again to make it work. This applies both when using Fusion software and when the board works on its own. I have pullup resistor on CNTRL line and do the toggling by pulling down the CNTRL line for awhile.

UCD9222 never turns the power supplies ON, when I select "Always converting". So I have operable power supplies only with Fusion software connected.

Can anyone help?

Regards, Asko

  • 0
    TI__Genius 9845 points
    The ENA1 and ENA2 pins you mentioned is probably GPIO pins of UCD9222, and these pins are configured as turn-on/stay-on dependency.

    Turn-on Dependency pins are only checked when the rail is commanded to turn on (toggle CONTROL pin, send OPERATION command, or Always-on at power-up). Stay-on Dependency pins are only checked when the rail is in regulation. Once the rail is turned off due to fault or de-assertion of stay-on dependency pins, you will need to command the rail to turn on again by toggling CONTROL or send OPERATION command. Toggling dependency pins cannot turn on the rails.

    You may connect UCD9222 CONTROL pin to UCD9090 to control the rails.

    Regards,
    Zhiyuan
  • 0 in reply to Zhiyuan Hu
    Prodigy 110 points

    Hi Zhiyuan,

    Thank you for your quick reply.

    Yes, ENA1 and ENA2 are enable pins of the two rails (actually the names in data sheet were EN1 and EN2). EN1 is pin 25, EN2 is pin 26.
    I cannot find turn-on/stay-on dependency for EN1, EN2 from Fusion software (I think I have the newest version, 2.0.120).

    What do you mean by "these pins are configured as turn-on/stay-on dependency"?

    On document SLUU490 those dependencies are mentioned , but I guess UCD9222 does not have them?

    UCD9222 data sheet says:
    "In addition to the PMBus_Cntrl pin supported by all UCD92xx products, the UCD9222 also supports separate
    Enable pins for each rail. The polarity of the EN1/EN2 pin is user-configurable, and will be the same as the
    polarity chosen for the PMBus_Cntrl pin by the ON_OFF_CONFIG command. When the ON_OFF_CONFIG
    setting is configured to respond the PMBus_Cntrl pin, the PMBus_Cntrl pin signal will be logically ANDed with
    the rail’s EN pin signal."

    From that statement I figured out the operation. I thought that when (on stand-alone operation) pull-up resistor is keeping CNTRL up and UCD9090 pulls up the EN1 and EN2 pins, the output rails should be turned ON. What is wrong on my conclusion?

    Regards,
    Asko

  • 0 in reply to Asko Oinonen
    TI__Genius 9845 points
    Hi Asko,

    The CONTROL pin is edge triggered, so you'll need to toggle the CONTROL pin to turn on a rail. To disable the CONTROL pin, you can choose ON_OFF_CONFIG to Always Converting. Then you can toggle EN1/EN2 pins to turn on the rail. The polarity of EN1/EN2 pins are the same as the CONTROL pin.

    Regards,
    Zhiyuan
  • 0 in reply to Zhiyuan Hu
    Prodigy 110 points

    Hi Zhiyuan,

    When I turn UCD9222 "Always converting", it never works. I tried the order both ENx first and CNTRL second, and visa versa, also pulsed controls. I have not been able to turn power ON ever, when the selection was "always converting". Does it even work on UCD9222?

    When I use "Control pin only", I can turn power ON when I toggle CNTRL. I guess only rising edge isn't enough, but there must be a low going pulse, am I right?

    When I manually control the CNTRL line by pulling it low (there's 10k pull-up resistor on pcb) sometimes one low pulse turns power on, sometimes I have to do pull-downs a few times. Quite strange.

    I connected CNTRL (UCD9222) to UCD9090 GPO pin, but did not manage to turn on the UCD9222 powers. The GPO output so far was only rising edge.

    I guess I have to make low pulse (high-low-high) with UCD9090 to turn UCD9222 power on. I haven't yet managed to do so. Any idea how to make a low going pulse to GPO?

    Any further advice in general?

    Regards,

    Asko

  • 0 in reply to Asko Oinonen
    TI__Genius 9845 points
    Here is what I did:

    ON_OFF_CONFIG is CONTROL Pin Only. Leave CONTROL = high (asserted. this polarity is configurable in GUI). I toggle EN pin, and rail can be turned on/off.

    Here is how it works inside device:
    When either CONTROL or EN are toggled, the FW starts to check CONTROL and EN level. When both CONTROL and EN levels are asserted (active high or active low, configurable), the rail will turn on.

    If pulse is too short, the device will not detect the toggling. But you should be able to pull CONTROL high or low in its assertion state, and use EN pin to control rails.

    Regards,
    Zhiyuan
  • 0 in reply to Zhiyuan Hu
    Prodigy 110 points
    Hi,

    Operation about the same with my prototype. Tried also without UCD9090 control to ENx pin (i.e. controlled it manually), but still having difficulties turning UCD9222 outputs ON every time. Are there slew rate requirements on ENx/CNTRL pins?

    I'm now struggling with UCD9090 to make a pulse (high-low-high) to rail control. There's some sort of state machine inside 9090, but I'm not sure if it's applicable to rail control output. I want to measure UCD9222 output voltage with power manager UCD9090.

    Regards,
    Asko
  • 0 in reply to Asko Oinonen
    TI__Genius 9845 points
    I set ON_OFF_CONFIG to CONTROL Only, CONTROL pin polarity to Active High, and pull CONTROL pin high all the time using the dongle, then I can manually pull ENx pin high to enable the rail, and low to disable the rail.

    There is no slew rate requirement. The device checks CONTROL and EN pin levels periodically. Either CONTROL pin or ENx pin state change will trigger the device to evaluate whether to turn on/off the rail. CONTROL and EN pins must both be asserted (active level) to turn on a rail.

    Regards,
    Zhiyuan
  • 0 in reply to Zhiyuan Hu
    Prodigy 110 points

    Hi,

    Starting problems on my digital power solved. The problem was not on operation of the power manager UCD9090, but on starting of the power stage UCD74111. I adjusted fault responses on my UCD9222 design to restart up to 5 times and got the prototype working. I guess the output caps on UCD74111 drew too much current on cold start and over current limits were exceeded. Default setting was "do not restart".

    Fault response setting tab marked on attached picture.

    Regards,

    Asko