IC-SP-06027 R0
5-2. Charge pump circuit
(1) Description of operation
·
Fig. 5-7 shows a block diagram of a charge pump circuit. The SW1 and SW2 repeat turning on and off
alternatively, synchronously with the internal clock.
·
When the SW1 is off and the SW2 is on, the CL pin has a potential of 0V. Through the passage (1),
charge the capacitor C1.
·
Next, the SW1 is turned on and the SW2 is turned off, and the CL pin rises in potential to the VS level.
Through the passage (2), the charge of the capacitor C1 is pumped up to the capacitor C2.
·
This operation is repeated with the frequency of the internal clock, and the charge is given to the
capacitor C2.
·
The capacitor C2 constitutes a power supply for the drive circuit for the top arm.
+
-
C2
C
-
C+
VS1,VS2
Vs
(2)
D2
C1
+
-
CL
D1
Vcc
(1)
SW1
Top arm
Driver
SW2
Internal
clock
MU,
MV,
MW
GH1,GH2
GL
Fig. 5-7. Charge pump circuit
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16
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