GTA02 voltage chart
Werner Almesberger
werner at openmoko.org
Wed Jul 16 14:16:32 CEST 2008
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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