Main Board Section - Panasonic KX-MB771GR Service Manual

Temperature AD value
[C°]
20 102
21 100
22 97
23 95
24 93
25 91
26 88

6.17. Main Board Section

3.3V Power Supply descriptions
• IC 302 decreases the output voltage when NPN transistor installed chopper amplifier type switching regulator produces 2.3A min
or over at the output voltage.
Oscillation frequency is set at approximately 500kHz.
• C375 and D302 are boost circuits as a base driving voltage for buit-in transistors.
• D301,R311,R312,R313,C375,Q300,R318,Q301are UVLO (Under Voltage Lock Out) circuit.
Q301 turns on when the in-out voltage is 17V or less and SS/SE terminal becomes low so that IC302's operation is stopped.
• D303 controls no to be a over voltage at 3.3V output when ICs including IC302 break down.
1.2V Power Supply descriptions
• IC305 is Nch FET used Switching Regulator with synchronous rectification system.
Oscillation frequency is set at approximately 350kHz.
• R356 is a resistor for decreasing the output voltage when the output current shows high.
The value is compared with the voltage drop at FET.
• C395 and D305 are FET's boost circuit as a gate driving voltage.
HEX reading Temperature
[C°]
66 67
64 68
61 69
5F 70
5D 71
5B 72
58 73
AD value HEX reading
30 1E
29 1D
28 1C
27 1B
27 1B
26 1A
25 19
59
Temperature AD value
[C°]
114 9
115 9
116 9
117 8
118 8
119 8
120 8
KX-MB771GR
HEX reading
09
09
09
08
08
08
08