User Guide

NMM-3 Company Confidential
7 - System Module & UI CCS Technical Documentation
Page 7-10 Copyright  2003 Nokia Corporation Issue 1 (11/2003)
Company Confidential
Battery temperature measurement
In Lynx batteries there are neither BTEMP pin nor NTC resistor. Battery’s temperature is
estimated by the measurement of a discrete NTC resistor in the phone located close to
the battery.
Backup Battery
To preserve the Real Time Clock (RTC), when the main battery is removed, a RTC back-up
capacitor B253 is installed in the phone. This 10uAh solution will give about 3hrs back-
up time in worst case.
The backup battery (capacitor) is connected between UEME VBACK and GND. In UEME
backup battery charging high limit is set to 3.2V. The cut–off limit voltage (VBUCoff–) for
backup battery is 2.0V. Backup battery
Charging is controlled by MCU by writing to UEME registers.
Power Up and Reset
Power up and reset is controlled by the UEME ASIC. NMM-3 baseband can be powered
up in following ways:
• Press power button which means grounding the PWRONX pin of the UEME
• Connect the charger to the charger input
• Supply battery voltage to the battery pin
• RTC Alarm, the RTC has been programmed to give an alarm
After receiving one of the above signals, the UEME counts a 20ms delay and then enters
it’s reset mode. The watchdog starts up, and if the battery voltage is greater than V
coff+
(2.1V) a 200ms delay is started to allow references etc. to settle. After this delay elapses
the VFLASH1 regulator is enabled. 500us later VR3, VANA, VIO and VCORE are enabled.
Finally the PURX (Power Up Reset) line is held low for 20 ms. this reset, PURX, is fed to
the baseband ASIC TIKU, resets are generated for the MCU and DSPs. During this reset
phase the UEME forces the VCTCXO regulator on regardless of the status of the sleep
control input signal to the UEME.
Signal Name Pin Number Function
VBAT 1 Positive battery terminal
BSI 2 Battery capacity measurement (fixed resistor inside the battery pack)
GND 3 Negative/common battery terminal