Panasonic DP-MB310EU - Main Board Power Supply Section; And 1.2 V Power Supply Descriptions; Power Supply Descriptions

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KX-MB2230EU/ KX-MB2270EU/ KX-MB2515EU/ KX-MB2545EU/ KX-MB2575EU/ DP-MB310EU
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.
R812
R815
R803
F22.1k
R804
C804
K1u
R820
C812 NC
()
R800
R816
C813
K1u
R806
R805
C814
K4700p
C809
C805
K4700p
+3.3V
Q803
+2.5VT
PWRDWN2
LVIN
C810
R809
R813
0(1608)
LVIN
C802
C803
R811
S3.3V
R801
+5VD
+1.2V
C806 D10p
R839
Q804
Q805
R818
R814
IC801
1
EN
2
VFB
3
VREG5
4
SS
5
GND1
6
SW
7
VBST
8
VIN
9
GND2
IC800
1
EN
2
VFB
3
VREG5
4
SS
5
GND1
6
SW
7
VBST
8
VIN
9
GND2
C824 R841
C825
NC
() R842
NC
()
C800
C807
C816
Q800
C831
C801
C808
10u/35V
L800
L801 2.2u
D803
D801
+1.2V
+3.3V
S5V
R840
LVIN
R810
C819
R802
C837
R808
R807
5.1k
Q801
1k
IC802
1
CE
2
VIN
4
BST
5
GND
3
LX
6
VFB
R817 10k
R845
C863
+5VD
C820
D804
S3.3V
Q802
D805
C830 C829
L802
+5V