Back-Up Battery And Real Time Clock; Baseband Measurement A/D Converter; Zocus - Nokia RM-51 Service Manual

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Charging
Charging control and charge switch is in UEMEK. There are two different charging modes; charging an empty
battery (start-up charge mode), and software controlled charging.
UEMEK digital part takes care of the charger detection (generates interrupt to UPP_WD2), pulse width modulated
charging control (for internal charge switch) and over voltage and current detection. These are all controlled
by software.
Chargers
The Baseband officially supports a standard charger (two wires); ACP-12 and cigarette charger LCH-12 .
Battery
The battery is a detachable, semi-fixed lithium-Ion BL-5B battery. The nominal voltage is 3.7 V (max 4.2 V).
The interface consists of three pins: VBAT, GND and BSI. A pull-down resistor inside the batteries (BSI signal)
indicates the battery types. The voltage level (75kΩ for BL-5B) at BSI line is measured using UEMEK's AD-converter.

Back-up battery and real time clock

The real time clock (RTC), crystal oscillator (VCXO)and back-up battery circuitry reside in UEMEK. A register in
UEMEK controls back-up battery charging. Charging is possible only in POWER_ON State.

Baseband measurement A/D converter

UEMEK contains an 11 channelled A/D converter, which is used for different baseband measurement purposes.
The resolution of the A/D converter is 10 bits. The converter uses the CBUS interface clock signal for the
conversion. An interrupt will be given to the MCU at the end of the measurements. The converter is used for the
following purposes.
• VBATADC, battery voltage
• BSI (Battery Size Indicator), the input is connected to ACI bus and the BSI_PULS. The BSI_PULS is delivered by
the flashing equipment when flashing the phone.
• BTEMP, battery temp
• PATEMP, power amplifier temp
• VCXOTEMP, power amplifier vendor indication
• Headint, interrupt from headset
• Hookint, interrupt from Hook button on headset
• The ALCO/LS input is used to determine the value of the BSI resisor of the Battery and thus the battery type
(and local, test modes)
• Headint2, not supported by SW, not used
• AuxDet, not used
• VBACK, test the voltage of backup battery

ZOCUS

The ZOCUS device is a current sensor used for the battery bar display and for determining whether the mobile
is in a high current consuming mode. The ZOCUS device measures the voltage drop across a sense resistor in
the battery voltage line. This sense resistor is formed from a PWB track and is on an internal layer of the PWB.
The sense resistor must be located close to the battery terminals so that all of the phones current flow through
it. The nominal value of the sense resistor is 3.0mΩ. ZOCUS reports the current measurement to UPP_WD2 via
the CBus interface.
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Copyright ©2005 Nokia. All Rights Reserved.
System module and user interface
9238460 (Issue 1)
RM-51