Nokia 8550 Service Manual
NSM–3/3D
System Module
System Module
PAMS Technical Documentation
Page 18
Issue 4 02/2002
Nokia Corporation
PWM
When a charger is used, the power switch is turned ON and OFF by the
PWM input. 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 pre-
vent the switching transients inducing noise in audio circuitry of the phone
soft switching is used.
PWM input. 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 pre-
vent the switching transients inducing noise in audio circuitry of the phone
soft switching is used.
Battery Identification
Different battery types are identified by a pulldown resistor inside the bat-
tery pack. The BSI line inside transceiver has a 100k pullup to VBB. The
MCU can identify the battery by reading the BSI line DC–voltage level
with a CCONT (N100) A/D–converter.
tery pack. The BSI line inside transceiver has a 100k pullup to VBB. The
MCU can identify the battery by reading the BSI line DC–voltage level
with a CCONT (N100) A/D–converter.
Name
Min
Typ
Max
Unit
Notes
BSI
0
2.8
V
Battery size indication
100k pullup resistor to VBB in phone
SIM Card removal detection
(Treshold is 2.4V@VBB=2.8V)
67
68
69
kohm
Indication of a BLB–2 battery (650 mAh Li–Ion)
0
1
kohm
Indication resistor for a service battery
SIMCardDetX
MAD
BSI
CCONT
2.8V
TRANSCEIVER
R
s
BATTERY
BSI
BGND
BTEMP
VBATT
10k
10n
100k
The battery identification line is used also for battery removal detection.
The BSI line is connected to a SIMCardDetX line of MAD2. SIMCardDetX
is a threshold detector with a nominal input switching level 0.85xVcc for a
rising edge and 0.55xVcc for a falling edge. The battery removal detection
is used as a trigger to power down the SIM card before the power is lost.
The BSI contact in the battery contact disconnects before the other con-
tacts so that there is a delay between battery removal detection and sup-
ply power off.
The BSI line is connected to a SIMCardDetX line of MAD2. SIMCardDetX
is a threshold detector with a nominal input switching level 0.85xVcc for a
rising edge and 0.55xVcc for a falling edge. The battery removal detection
is used as a trigger to power down the SIM card before the power is lost.
The BSI contact in the battery contact disconnects before the other con-
tacts so that there is a delay between battery removal detection and sup-
ply power off.