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6.2.8. POWER SUPPLIES (SEE Fig. 23)
The AC Adaptor for the KX-TCD953 / KX-TCD958 consists of two separate isolated DC supplies providing a +8 V supply for the
base circuitry, and a 9 V supply only for the charger circuit. The isolation is because the main base circuitry is connected to the
telephone line, so potentially hazardous voltages may be present, while the charger circuitry has charge contacts that could be
touched by the operator, so the two supplies must be kept separate. The 8 V supply from the AC Adaptor is connected via J2 pin
1 (TP90) +8 V, and J2 pin 2 (TP89) ground. The unregulated +8 V supply is fed to the first regulator.This regulator IC7 provides
a regulated output pin 2 (TP91) of +4.0 V (called +4V). The second regulator IC11 is fed with +4V and provides the stable +3.2V
supply (TP95). During power-up this regulator generates a RESET signal (TP94) which is used to reset the microcontroller and
BBIC.
base circuitry, and a 9 V supply only for the charger circuit. The isolation is because the main base circuitry is connected to the
telephone line, so potentially hazardous voltages may be present, while the charger circuitry has charge contacts that could be
touched by the operator, so the two supplies must be kept separate. The 8 V supply from the AC Adaptor is connected via J2 pin
1 (TP90) +8 V, and J2 pin 2 (TP89) ground. The unregulated +8 V supply is fed to the first regulator.This regulator IC7 provides
a regulated output pin 2 (TP91) of +4.0 V (called +4V). The second regulator IC11 is fed with +4V and provides the stable +3.2V
supply (TP95). During power-up this regulator generates a RESET signal (TP94) which is used to reset the microcontroller and
BBIC.
The regulator IC6 provides a regulated output pin 2 (TP109) of +6.0V.
6.2.9. BATTERY CHARGER (SEE Fig. 23)
The 9 V supply from the AC Adaptor is connected via J2 pin 6 (TP82) positive, and J2 pin 5 (TP78) negative. The constant current
battery charger circuit is made up of T14 and T15 (series pass transistor) and associated components. Charging detector circuit
T16 switches on when a charging current flows through R64 and D11, and turns on IC6. The charge contacts are charge current
flows in via J5 (TP88), through T15, R63, AC ADAPTOR 4V supply, R64, D11, and out of J5 (TP84).
battery charger circuit is made up of T14 and T15 (series pass transistor) and associated components. Charging detector circuit
T16 switches on when a charging current flows through R64 and D11, and turns on IC6. The charge contacts are charge current
flows in via J5 (TP88), through T15, R63, AC ADAPTOR 4V supply, R64, D11, and out of J5 (TP84).
Circuit Diagram
Fig. 23
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KX-TCD953RUB
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