Charger Detection; Charge Control - Nokia RM-11 Series Troubleshooting Manual

RM-11
Troubleshooting - Baseband

Charger Detection

Connecting a charger creates voltage on VCHAR input of the UEM. When VCHAR input
voltage level is detected to rise above 2 V (VCHdet+ threshold) by UEM charging starts.
VCHARDET signal is generated to indicate the presence of the charger for the software.
The charger identification/acceptance is controlled by EM software.
The charger recognition is initiated when the EM software receives a "charger
connected" interrupt. The algorithm basically consists of the following three steps:
1. Check that the charger output (voltage and current) is within safety limits.
2. Identify the charger as a two-wire or three-wire charger.
3. Check that the charger is within the charger window (voltage and current).
If the charger is accepted and identified, the appropriate charging algorithm is initiated.
X102
F100
2
1.5A
1

Charge Control

In active mode, charging is controlled by the UEM's digital part. Charging voltage and
current monitoring is used to limit charging into a safe area. For that reason, the UEM
has programmable charging cut-off limits:
• VBATLim1=3.6 V (Default)
• VBATLim2L=5.0 V and
• VBATLim2H=5.25 V.
VBATLim1, 2L, 2H are designed with hystereses. When the voltage rises above VBATLim1,
2L, 2H+ charging is stopped by turning the charge switch off. There are no changes to
the operational mode. After voltage has decreased below VBATLim-, charging re-starts.
There are two PWM frequencies in use depending on the type of the charger: the 2-wire
charger uses a 1 Hz and a 3-wire charger uses a 32 Hz. The duty cycle range is 0% to
©2005 Nokia Corporation
Page 26
L100
________
42R/100MHz
V100
Figure 12: Charging circuit
Confidential
CC Technical Documentation
0
"VCHARIN"
C106 C110
2
1n0 22p
Issue 2 09/2005
CHARGER(4:0)