Different Pwm Frequencies (1Hz And 32 Hz) - Nokia NSB-5 Series Technical Documentation Manual

PAMS Technical Documentation
VCH Vpor
(Standard
Charger)
VLIM
VOUT
4V
Vstart
PWM
"1"
"0"
ON
SWITCH
OFF
1
1 Battery removed, (standard) charger connected, VOUT rises (follows charger volt-
age)
2 VOUT exceeds limit VLIM(X), switch is turned immediately OFF
3 VOUT falls (because no battery), also VCH<Vpor (standard chargers full–rectified
output). When VCH > Vpor and VOUT < VLIM(X) –> switch turned on again (also
PWM is still HIGH) and VOUT again exceeds VLIM(X).
4 Software sets PWM = LOW –> CHAPS does not enter PWM mode
5 PWM low –> Startup mode, startup current flows until Vstart limit reached
6 VOUT exceeds limit Vstart, Istart is turned off
7 VCH falls below Vpor

Different PWM Frequencies (1Hz and 32 Hz)

When a travel charger (2–wire charger) is used, the power switch is turned ON and OFF
by the PWM input when the PWM rate is 1Hz. When PWM is HIGH, the switch is ON and
the output current Iout = charger current – CHAPS supply current. When PWM is LOW,
the switch is OFF and the output current Iout = 0. To prevent the switching transients
inducing noise in audio circuitry of the phone soft switching is used.
Issue 1 03/01
Droop depends on load
& C in phone
2 3 4 5
Nokia Mobile Phones Ltd.
Istart off due to VCH<Vpor
Vstarthys
6 7
NSB-5
System Module
t
t
t
Page 27