Startup Charging; Battery Overvoltage Protection - Nokia NSB-5 Series Technical Documentation Manual

PAMS Technical Documentation

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 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 con-
trolled by the MCU software. If the battery voltage reaches 3.55V (3.75V maximum)
before the program has taken control over the charging, the startup current is switched
off. The startup current is switched on again when the battery voltage is sunken
100mV (nominal).
Table 6: Startup Charging Parameters
Parameter
VOUT start-up mode cutoff limit
VOUT start-up mode hysteresis
Note: COUT = 4.7µF
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 different 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)
Output voltage cutoff limit (no
transmission or Ni-battery)F
The voltage limit (VLIM1 or VLIM2) is selected by logic LOW or logic HIGH on the CHAPS
(N101) LIM– input pin. Default value is lower limit VLIM1.
Issue 1 03/01
Symbol Min
Vstart 3.45
Vstarthys 80
Istart 130
Table 7: Battery Overvoltage Protection
LIM
Symbol
input
VLIM1 LOW
VLIM2 HIGH
Nokia Mobile Phones Ltd.
System Module
Typ Max Unit
3.55 3.75 V
100 200 mV
165 200 mA
Min Typ Max
4.4 4.6 4.8
4.8 5.0 5.2
NSB-5
Unit
V
V
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