Operation - Benefon SIGMA GOLD TDP-52-SN3 Service Manual

8.1.3 Operation

8.1.3.1 General
Power supply unit is connected to one of the connectors on the back of the unit.
Connections on these two connectors are identical to each other. Supply voltage
(VB) turns on regulator I124 which is used to generate +5 VDC supply (VCC) for pro-
cessor and other electronics. Note that the power amplifiers of the earphone signal,
I499 and I528 do not use VCC but VB instead. Once the VCC signal has risen, also
signal CADET is activated. This causes the phone to communicate with the I2C cir-
cuit and register that office kit is present.
8.1.3.2 Processor / charging
The processor I264 is National Semiconductor COPCF888. Crystal frequency used
is 8,00 MHz.
I/O pins/signals are as follows:
I/O SIGNALS
C0
C7
D0
D1
D2
D3
D4
D5
D6
D7
G3
I0
I1
I2
I3
I4
A/D input I3 is used to measure the voltage of the spare battery. Amplifier I277 con-
verts the input voltage level into the new range which is suitable for A/D input. Out-
put G3 is a PWM signal which is converted with R291 and C293 into analog DC
signal. This signal is used to control the output current of the power supply unit. Out-
puts D0 and D1 are used to turn on charging current for the phone and spare bat-
tery. P-channel fets Q211 and Q221 are normally in non-conducting state (gate
voltage tied to VB) and are turned on with fets Q212 and Q222 as the control signal
has been activated. In normal operation fets Q211 and Q221 are never simulta-
neously in the conducting state.
8dds50gb_fm5.fm
spare battery discharge switch
battery pack memory
phone charge fet control
spare battery charge fet control
spare battery discharge control
phone detect current control
phone charge indicator (red) controlOUT
phone charge indicator (green) control
spare battery charge indicator (red) control
spare battery charge indicator (green) control
power supply control
charger control from phone
spare battery temperature
phone battery voltage
spare battery voltage
PWM_CHK (not used)
Product: DDS-50(Office set) /
27.1.1999
YO0311
DIRECTION
IN
IN / OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
IN
IN
IN
IN
IN
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