User Guide

NSM–3
System Module
PAMS Technical Documentation
Page 13
Issue 1 12/1999
 Nokia Mobile Phones Ltd.
VIN
CHAPS
10k
1n
PWM
VBAT
GND
CCONT
L_GND
CHARGER
PWM_OUT
TRANSCEIVER
0R22
VCHAR
ICHAR
100k
22k
1u
2A
30V
VCH
VOUT
RSENSE
GND
CCONTINT
MAD
LIM
MAD
Startup Charging
When a charger is connected, the CHAPS is supplying a startup current
minimum of 130mA to the phone. The startup current provides initial
charging to a phone with an empty battery. Startup circuit charges the
battery until the battery voltage level is reaches 3.0V (+/– 0.1V) and the
CCONT releases the PURX reset signal and program execution starts.
Charging mode is changed from startup charging to PWM charging that is
controlled by the MCU software. If the battery voltage reaches 3.55V
(3.75V maximum) before the program has taken control over the charg-
ing, the startup current is switched off. The startup current is switched on
again when the battery voltage is sunken 100mV (nominal).
Parameter Symbol Min Typ Max Unit
VOUT Start– up mode cutoff limit Vstart 3.45 3.55 3.75 V
VOUT Start– up mode hysteresis
NOTE: Cout = 4.7 uF
Vstarthys 80 100 200 mV
Start–up regulator output current
VOUT = 0V ... Vstart
Istart 130 165 200 mA
Battery Overvoltage Protection
Output overvoltage protection is used to protect phone from damage.
This function is also used to define the protection cutoff voltage for differ-
ent battery types (Li or Ni). The power switch is immediately turned OFF if
the voltage in VOUT rises above the selected limit VLIM1 or VLIM2.
Parameter Symbol LIM input Min Typ Max Unit
Output voltage cutoff limit
(during transmission or Li–
battery)
VLIM LOW 4.4 4.6 4.8 V