Epson Power Supply IC S1F70000 Technical Manual page 69

S1F76540 Series
Setup:
• Relationship between V
R1 + R2
V =
REG
• Current consumption of division resistors
| V
I =
REG
R1 + R2
Setup example:
• To output V = –18 V by four-time boosting if V
REG
First, determine the total resistance of division resistors R1 and R2. If the current consumption is assumed to be 20
A, the total resistance can be obtained from equation (2) as follows:
R1 + R2 = 12V 20 A = 900 k
If the reference voltage is -1.5 V, the division resistance ratio can be obtained from equation (1) as follows:
(R1 + R2) / R2 = (–18 V) (–1.5 V) = 12
Therefore, R1 and R2 are:
R1 = 75 k
R2 = 825 k
2–26
R1 R2
Figure 2.5 V
and reference voltage
REG
(Reference voltage)
R1
|
REG
1 V C2P
O
2 V C2N
RI
3 V C3N
REG
4 RV C1N
5 V C1P
DD
6 FC
7 TC1 P
8 TC2 P
setup and mounting notes
REG
= –5 V and V
I
EPSON
16
15
14
13
12
V 11
I
10
OFF1
9
OFF2
• • • • Equation (1)
• • • • Equation (2)
= –20 V
O
S1F70000 Series
Technical Manual