Powering Off; Uncontrolled Powering Off; Watchdogs; Charging - Nokia RH-47 Series Description
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Also See for RH-47 Series:
- Rf description and troubleshooting (76 pages) ,
- Disassembly & assembly instructions (22 pages)
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RH-47
7 - Baseband Description & Troubleshooting
tor charges the capacitor(s) at the output with the maximum current (short circuit cur-
rent) it can deliver. This results in battery voltage dropping during start-up. When a
battery with voltage level just above the hardware cutoff limit is inserted, the system
may not start due to excessive voltage dipping. Dropping below 2.8 V for longer than 5
ms forces the system to PWR_OFF state.
Powering off
Controlled powering off is done when the user requests it by pressing the power-key or
when the battery voltage falls too low. Uncontrolled powering off happens when the
battery is suddenly removed or if over-temperature condition is detected in regulator
block while in RESET mode. In this mode, all UEM's regulators are disabled immediately
and discrete regulators are disabled as Vbat supply disappears.
Controlled powering off
For RH-47, powering off is initiated by pressing the power key. After that power off
sequence is activated in the UEM and SW. Basically, power key causes a UEM Interrupt to
UPP_WD2 and SW sets watchdog time value to zero and as this happens, PURX is forced
low and all regulators are disabled. If the battery voltage falls below the very last SW-
cutoff level, SW will power off the system by letting the UEM's watchdog elapse. If ther-
mal shutdown limit in UEM regulator block is exceeded, the system is powered off. Sys-
tem reset PURX is forced low.
Uncontrolled powering off
This happens when the battery is suddenly removed. UEM's state machine notices battery
removal after battery voltage has been below V
mode. PURX is set low and all UEM's regulators are disabled.
Watchdogs
There are three watchdogs in the UEM. The first one is for controlling system power-on
and power-down sequences. The initial time for this watchdog after reset is 32s and the
watchdog can not be disabled. The time can be set using a register. This watchdog is used
for powering the system off in a controlled manner. The other one is for security block
and is used during IMEI code setting. The third one is a power key watchdog. It is used to
power off the system in case SW is stuck and the user presses the power key.
There is also a"soft watchdog" in UPP_WD2. It is used to reset the chip in case software
gets stuck for any reason. The Bluetooth module also contains a watchdog.
Charging
Charging control and charge switch is in the UEM. There are two different charging
modes: charging empty battery (start-up charge mode), and SW controlled charging.
UEM digital part takes care of charger detection (generates interrupt to UPP_WD2),
pulse width modulated charging control (for internal charge switch) and over voltage
and current detection. SW using registers controls all these.
Page 12
Company Confidential
Copyright © 2004 Nokia Corporation
Company Confidential
Nokia Customer Care
for 5 us and enters the PWR_OFF
COFF-
Issue 1 05/04
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Troubleshooting
