Main Board Power Supply Section; And 1.2V Power Supply Descriptions; Power Supply Descriptions - Panasonic KX-MB2230JT Service Manual

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KX-MB2230JT/ KX-MB2270JT/ KX-MB2515JT/ KX-MB2545JT/ KX-MB2575JT/ DP-MB310JT

6.18. Main Board Power Supply Section

6.18.1. 3.3V and 1.2V Power Supply Descriptions

1. IC800, IC801 is Synchronous Step-Down DC/DC Converter with Auto-Skip Eco-mode to increase light load efficiency.

2. Oscillation frequency is set at approximately 700kHz (Frequency is changed at Light Load.).

3. Q803,Q804,Q805,R809,R815,C812,R816,R818,C831,R814 are Sequence circuit. (After 1.2V DC-DC converter is turned on,

3.3V(IC801)'s operation is turned on.)

4. D803, D801 are the Zener Diode for Over voltage protection.

5. Q800, R839, C800, R820 are the switch circuit which turns off a S3.3V power supply at the time of Sleep mode.

6.18.2. 5V Power Supply Descriptions

1. IC801 is PWM type DC-DC converter with an internal power MOSFET , which make up step down type DC-DC converter cir-

cuit with coil of L802, schottky diode of D804, Capacitor of C819,C820 and C829.

2. D805 is the Zener Diode for Over voltage protection.

3. Q801,R823,C821,R824,Q802 are the switch circuit which turns off a S5V power supply at the time of Sleep mode.

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