Startup Charging; Battery Overvoltage Protection - Nokia NSM-3 Series Technical Documentation Manual

PAMS Technical Documentation
MAD
0R22
VBAT ICHAR
PWM_OUT
MAD
CCONTINT
VCHAR
CCONT
GND

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
VOUT Start– up mode cutoff limit
VOUT Start– up mode hysteresis
NOTE: Cout = 4.7 uF
Start–up regulator output current
VOUT = 0V ... Vstart

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
Output voltage cutoff limit
(during transmission or Li–
battery)
Issue 4 02/2002
LIM
TRANSCEIVER
VOUT
CHAPS
RSENSE VCH
1u
GND
PWM
100k
22k
1n
10k
Symbol
Vstart
Vstarthys
Istart
Symbol LIM input
VLIM LOW
E Nokia Corporation
System Module
2A
VIN
30V
L_GND
Min Typ Max
3.45 3.55 3.75
80 100 200
130 165 200
Min Typ Max
4.4 4.6
NSM–3/3D
CHARGER
Unit
V
mV
mA
Unit
4.8 V
Page 15