Battery charger for the PUMA T2 hand-held radio
Technical Manual
Functional Description
Page 28
OTE Proprietary Information
P/N: 779-0357/02
Revision 04
The microcontroller operates on the base of the voltage values present on the
battery terminals, at the thermistors of the batteries and on the resistive branches
to identify the battery type to be charged. The microcontroller select one out of the
six lines to be measured by using “0”, “1”, and “2” signals.
The measurement circuit is enabled via the START signal. Measurement is carried
out by generating a reference ramp signal and comparing it to the signal to be
measured.
When the levels of the two signals are equivalent, a comparator switches.
The microcontroller converts the output signal, just measured, to a voltage value
on the base of the time passed from the beginning of the measurement.
LED circuit
The eight LEDs (the four LEDs relative to the upper slot and the ones relative to
the lower slot) present for each couple of charging slots (one couple for the BCP2-
850 model and three couples for the BCP6-850 one) are activated by the LED
circuit.
The ON/OFF commands are multiplexed on four lines.
Each LED status is stored to a memory by a latch enabled by the microcontroller.
Battery contacts
In every charging slot (two for the BCP2-850, six for the BCP6-850) five electrical
contacts providing the battery interface are present.
The five contacts and their meaning are shown in fig. 3.6.
Fig. 3.6:
Battery contacts
The identification of the battery is carried out by reading the voltage value on #2
contact. Inside the battery pack this contact is connected to a grounded resistor
which can have different values depending on the battery type. Those values are
shown in tab. 3.3.
1 2 3 4 5
1. Negative (battery)
2. Battery identification
b tt i
3. NTC connection
4. Positive (battery)
5. Radio power supply
