Siemens SXG 75 Service Repair Documentation page 42

• After an interval several conditions are checked to determine the next action:
o If the over-temperature threshold was exceeded then the PON_RESET_N signal is immediately
driven low and all PM6650 circuits are turned off. The over-temperature feature
protects the PM6650 IC and cannot be disabled.
o If VPH_PWR is below the set threshold then the PON_RESET_N signal is immediately
driven low and all PM6650 circuits are turned off. This feature protects the battery and
cannot be disabled.
o If the over-temperature threshold was not exceeded, VPH_PWR is above the threshold,
and the watchdog restart bit is set then the watchdog interrupt status bit is set, the MSM
device is restarted, its watchdog timer is reset, and the PM6650 IC is restarted without
fully powering down.
o If the over-temperature threshold was not exceeded, VPH_PWR is above the threshold,
and the Sudden Momentary Power Loss (SMPL) function is enabled then the SMPL recovery
is executed.
• If none of the above combinations occur, the normal power-down sequence is continued.
• The remaining regulators are powered down in the following sequence:
o VREG_MSMA
o VREG_MSMP
o all others
• An interval is allowed for both the MSMA and MSMP regulator outputs to discharge before all the
other regulators are turned off. Another interval passes then the bandgap reference and all other
unneeded circuits are disabled.
• The PM6650 IC turns off the battery MOSFET by driving BAT_FET_N high and makes sure the
external supply is disconnected by driving CHG_CTL_N high. With all sources disconnected the
PM6650 has no applied power and the phone is powered down.
• PM6650 IC is now OFF.
Technical Documentation
TD_Repair_L3_SXG75_R1.0.pdf
Company Confidential
2006©BenQ
Release 1.0
01/2006
Page 42 of 73