MC7660 查看數據表（PDF） - ON Semiconductor

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MC7660

Charge Pump DC-to-DC Voltage Converter

ON Semiconductor 

MC7660

Efficient Positive Voltage Multiplication/Conversion

Since the switches that allow the charge pumping

operation are bidirectional, the charge transfer can be

performed backwards as easily as forwards. Figure 11 shows

a MC7660 transforming -5.0 V to +5.0 V (or +5.0 V to

+10 V, etc.). The only problem here is that the internal clock

and switch-drive section will not operate until some positive

voltage has been generated. An initial inefficient pump, as

shown in Figure 10, could be used to start this circuit up,

after which it will bypass the other (D1 and D2 in Figure 10

would never turn on), or else the diode and resistor shown

dotted in Figure 11 can be used to “force” the internal

regulator on.

+

C1

10 mF

VOUT = -V-

1

8

2

7

MC7660

3

6

4

5

1 MW

+

10 mF

V- INPUT

Figure 11. Positive Voltage Conversion

Voltage Splitting

The same bidirectional characteristics used in Figure 11

can also be used to split a higher supply in half, as shown in

Figure 12. The combined load will be evenly shared between

the two sides. Once again, a high value resistor to the LV pin

ensures start-up. Because the switches share the load in

parallel, the output impedance is much lower than in the

standard circuits, and higher currents can be drawn from the

device. By using this circuit, and then the circuit of Figure 6,

+15 V can be converted (via +7.5 V and -7.5 V) to a nominal

-15 V, though with rather high series resistance (~250 W).

V+

+

RL1

50 mF

VOUT

+

V)

*

2

V–

RL2

50 mF +

-

100 kW 100 kW

1

8

2

7

MC7660

3

6

4

5

1 MW

+

50 mF -

V-

Figure 12. Splitting a Supply in Half

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