S1F76620 Series

Negative Voltage Conversion

S1F76620 can boost input voltage to twice on the positive potential side by using the circuit shown in Figure 6. But the output voltage drops by the forward voltage VF of the diode. When GND is 0V, VDD is 5V and VF is 0.6V as shown in Figure 6 for example, VO is calculated as follows: VO = –5V + 2× 0.6V = –3.8V.

1 POFF

VO 8

2 GND CAP1+ 7

3 OSC1 CAP1– 6

4 OSC2

VDD 5

S1F76620

Series

+ –

+ –

VO'

Figure 6 Negative Voltage Conversion

Negative Voltage Conversion + Positive Voltage Conversion

When the 3 times step-up operation shown in Figure 1 and the positive voltage conversion in Figure 6 are combined, the circuit shown in Figure 7 can be formed and 10V and –3.8V can be obtained from the input 5V. However, the output impedance is higher than in case of connection of either one only (the negative voltage conversion or the positive voltage conversion).

 

 

 

 

VO1

Potential Relations Diagram

 

 

 

 

 

 

1

POFF

VO

8

 

 

 

2 VI

 

 

 

 

 

 

 

2

GND

CAP1+

7

+

+

VDD

 

 

 

 

 

 

 

–

–

VI

 

3

OSC1

CAP1–

6

 

 

VSS

–VI+2•VF

 

 

 

 

 

 

4

OSC2

VDD

5

 

 

 

VO2

 

 

 

 

 

 

 

 

 

 

 

 

 

VO2

 

Figure 7 Negative Voltage Conversion + Positive Voltage Conversion

S1F70000 Series Technical Manual

EPSON

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