Epson – Epson Power Supply S1F70000 User Manual
Page 40
S1F76620 Series
S1F70000 Series
EPSON
1–23
Technical Manual
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 V
F
of the diode. When GND is 0V, V
DD
is 5V and V
F
is 0.6V as
shown in Figure 6 for example, V
O
is calculated as follows: V
O
= –5V + 2
×
0.6V = –3.8V.
P
OFF
V
O
'
+ –
GND
OSC1
OSC2
V
O
CAP1+
CAP1–
V
DD
1
2
3
4
8
7
5
+ –
6
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).
P
OFF
V
O2
V
O1
GND
OSC1
OSC2
V
O
V
DD
2 V
I
V
SS
–V
I
+2 V
F
V
O2
V
I
CAP1+
CAP1–
V
DD
1
2
3
4
8
7
5
6
+
–
+
–
Potential Relations Diagram
•
Figure 7 Negative Voltage Conversion + Positive Voltage Conversion