Charging Control; Two-Wire Charging - Nokia NSW-5 Series Service Manual

PAMS Technical Documentation
V5V is used for RF parts only. It can be switched off by the RFCEN signal.
VR1 is used for the VCXO supply, and VR6 is used in COBBA for analog
parts. RFCEN signal to CCONT controls both VR1 and VR6 regulators;
they can be switched off in sleep modes, and during standby. During
sleep VR6 output pin is connected to VBB regulator inside CCONT.
CCONT regulators are controlled either through SIO from MAD or timing
sensitive regulators are controlled directly to their control pins. These two
control methods form a logical OR–function, i.e. the regulator is enabled
when either of the controls is active. Most of the regulators can be con-
trolled individually.
CHAPS connects the charger voltage (VCHAR) to battery. MCU of MAD
controls the charging through CCONT. MAD sets the parameters to
PWM–generator in CCONT and PWM–output controls the charging volt-
age in charger.
When the battery voltage is below 3.0V, CHAPS controls independently
the charging current.

Charging Control

Charging is controlled by MCU SW, which writes control data to CCONT
via serial bus. CCONT output pin PWMOUT (Pulse Width Modulation)
can be used to control both the charger and the CHAPS circuit inside
phone. Charging control diagram below.
Vin
System
Connector
PWMOUT
To
Charging Control
charger
Two–wire charging
With 2–wire charging the charger provides constant output current, and
the charging is controlled by PWMOUT signal from CCONT to CHAPS.
The PWMOUT signal frequency set is 1 Hz, and the charging switch in
CHAPS is pulsed on and off at this frequency. The final charged energy to
battery is controlled by adjusting the PWMOUT signal pulse width.
Issue 1 10/00
CHAPS BATTERY
CCONT
E Nokia Mobile Phones Ltd.
System Module UT5U
MAD
serial control
NSW-5
Page 17