GTA02 voltage chart

Michael Shiloh michael at
Wed Jul 16 20:00:33 CEST 2008

Wow! This is excellent information. I'm putting in my resources (somewhere).



Werner Almesberger wrote:
> Since the voltage levels at which various things happen are getting a
> bit confusing, here's a quick overview:
> Voltage Where   What happens
>  4.5 V  USB     USB voltage required for battery charging
>         USB     Minimum USB voltage at device guaranteed by USB 2.0
>  4.2 V  BAT     Battery float voltage (NoPower default and u-boot setting)
>  3.6 V  USB     +/- 0.35V, USB adapter present (rising)
>  3.5 V  USB     +/- 0.35V, USB adapter present (falling)
>  3.4 V  BAT     u-boot wait_for_power threshold
>  3.1 V  SYS     Minimum SYS voltage, interrupt and timeout (set by u-boot)
>         BAT     Battery threshold (NoPower default)
>  3.0 V  SYS     Minimum SYS voltage, interrupt and timeout (NoPower default)
>  2.85V  BAT     Battery conditioning (NoPower default)
>  2.8 V  BAT     Battery threshold (set by u-boot)
>  2.7 V  BAT     Battery conditioning (set by u-boot)
>  2.5 V  SYS     SYS voltage for immediate shutdown into Save mode
>  2.4 V  BAT     GTA02 battery cuts off
>  2.2 V  BAT     GTA01 battery cuts off
>  2.0 V  SYS     +/- 0.3V, SYS voltage to enter Save/NoPower
>  1.3 V  BUB     +/- 0.3V, Backup battery present threshold
>  0.0 V  BAT     No battery or battery in cut-off
> NoPower default means that the PMU sets this value if without any power,
> i.e., no mai battery, no USB, and the backup battery is below 1.3V. If
> SYs remains at at least 2.0V or the backup battery is above 1.3V, the
> PMU will remember the previous settings.
> u-boot changes some of the PMU settings during early initialization.
> The SYS voltage is basically max(USB, BAT) and all the PMU's regulators
> are supplied from it.
> - Werner

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