Controller - Motorola 38C V100 Service Manual

Circuit Description

Controller

14
• AOC_DRIVE (U390 Pin 8) controls the output power of the transmitter. Under
normal conditions, the control loop will adjust the voltage on EXC so that the
power level presented to the RF detector results in equal voltages present at
INT and AOC. The input level is between 0 and 2.5V.
• ACT (U390 Pin 9). With no RF present, this pin stays high. Once the RF level
increases enough to cause the detector output to rise a few millivolts, this out-
put goes low. ACT is connected to the AOC input through a resister which
causes the transmitter to ramp-up the power until the detector goes active.
Power-Up sequence
The three power sources available for the PF38C Personal Communicator are:
• Internal battery
• External power via mid-rate charger (Battery must be present to power up)
• External power via fast charger (Battery must be present to power up)
Battery Power Source
The Personal Communicator uses a 3.6V Lithium Ion battery. Power from the
battery is taken from BATT + (battery contacts J604) and routed through battery
FET Q901. Once B+ is available, the unit carries out the following checks.
• Battery temperature is measured to establish whether rapid charge is
required. Table 2 shows voltages appearing at BATT_THERM_AD (J604 Pin 3
and GCAP II Pin B3) for various battery temperatures.
Table 2. Battery Temp vs. BATT_THERM_AD
• Presence and type of charger is sensed MANTEST_AD (J600 Pin 5 and GCAP
II Pin A1). This is achieved by using different sense resistors within each type
of charger.
Table 3. Charger Type vs. MANTEST_AD
Mid-Rate Charger
• Battery voltage is sensed (GCAP II Pin F7 BATTERY).
• Input B+ level is sensed (GCAP II Pin E10 B+).
Charger Power Source
When the charger is connected to accessory plug J600, EXT B+ is available at
Pin 14 and sensed at MOBPORTB (GCAP II U900 Pin D10). Once sensed, the
power is passed through protection diode CR903 and output to EXT B+ FET Q905.
The output is controlled by MIDRATE_1 and power is made available at B+.
Because the charger supports both the Personal Communicator and its internal
battery, the battery is charged at the same time B+ is supplied to operate the unit.
MOTOROLA CONFIDENTIAL - PROPRIETARY
November 20, 2000
-40° C
25° C
40° C
Fast Charger
Product Family 38C
2.75V
1.39V
0.96V
2.13V
1.38V
6881036B20