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9.1.8. FACTORY SERIAL PORT (SEE Fig. 25)
In order to communicate with the handset during manufacture and servicing (using a PC) a serial data link has been provided.
Serial data input/output is provided on J6 (TP65), and a ground is provided on J7. The bi-directional serial data line is split into two
at IC1 pin 27 (input) and pin 26 (output). Data rate is 9600 baud or 115.2 kBaud. D13 provides ESD protection, and R37 and C56
provide RF de-coupling.
Serial data input/output is provided on J6 (TP65), and a ground is provided on J7. The bi-directional serial data line is split into two
at IC1 pin 27 (input) and pin 26 (output). Data rate is 9600 baud or 115.2 kBaud. D13 provides ESD protection, and R37 and C56
provide RF de-coupling.
9.1.9. BUZZER CIRCUIT (SEE Fig. 29)
A square-wave signal from IC1 pin 45 is used to sound the buzzer via switching transistor T5 (TP22). Various tones and cadences
are used dependent on function. Buzzer volume is varied by changing the duty cycle of the drive waveform. D11 provides
quenching of back-emf generated when T5 turns off.
are used dependent on function. Buzzer volume is varied by changing the duty cycle of the drive waveform. D11 provides
quenching of back-emf generated when T5 turns off.
9.1.10. BATTERY SUPPLY (SEE Fig. 29)
The three cell NiCd/NiMH rechargeable battery supplies the handset via 2A fuse (actually a coil), and is de-coupled by C3 and C4.
It directly supplies T3 in the baseband section, and also the Tx PA in the RF Section. It also supplies IC1 (de-coupled by C9), and
most of the RF Section (VCC-OC) (decupled by R35 and C47, C48 and VCC-PA).
It directly supplies T3 in the baseband section, and also the Tx PA in the RF Section. It also supplies IC1 (de-coupled by C9), and
most of the RF Section (VCC-OC) (decupled by R35 and C47, C48 and VCC-PA).
9.1.11. MAIN 3V REGULATOR (SEE Fig. 29)
The BBIC measures the battery voltage on pins 58 using an internal ADC. If the battery voltage is below 3.36 V, TC3 is switched
to power off mode. R7 and C5 provide a reset pulse (TP84) used for resetting the BBIC when power on. The +3 V supply (TP10)
is fed to the BBIC, Flash PROM, EEPROM, and Display Driver.
to power off mode. R7 and C5 provide a reset pulse (TP84) used for resetting the BBIC when power on. The +3 V supply (TP10)
is fed to the BBIC, Flash PROM, EEPROM, and Display Driver.
9.1.12. BATTERY CHARGING CIRCUIT (SEE Fig. 29)
The charge circuit is designed to operate with a constant current charger in the base. L1, L2, D2 and D4 protect against electro-
static discharge (ESD). The charging current from the base is turned on and off by T1 using a control signal from the BBIC (pin 39,
TP6) via T2. R3 provides initial current in the event of a totally flat battery, and D6 protects against the high voltage present on the
charge contacts if there is no battery in the handset. R4 and R5 provide a signal for the BBIC to detect (pin 40) that the handset
had been placed on the base charger. If the handset is off, it will be switched on, and charging will start. D2, D3, D4, and D5 act
as steering diodes to enable the handset to be placed on the cradle either way up (i.e. the handset is reversible).
static discharge (ESD). The charging current from the base is turned on and off by T1 using a control signal from the BBIC (pin 39,
TP6) via T2. R3 provides initial current in the event of a totally flat battery, and D6 protects against the high voltage present on the
charge contacts if there is no battery in the handset. R4 and R5 provide a signal for the BBIC to detect (pin 40) that the handset
had been placed on the base charger. If the handset is off, it will be switched on, and charging will start. D2, D3, D4, and D5 act
as steering diodes to enable the handset to be placed on the cradle either way up (i.e. the handset is reversible).
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KX-TCD953RUB
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