S1F76540 Series

 

1

VO

C2P 16

 

2

VRI

C2N 15

R1

R2

VREG

C3N 14

 

3

 

4

RV

C1N 13

 

5

VDD

C1P 12

 

6

FC

VI 11

 

7

TC1

POFF1 10

 

8

TC2

POFF2 9

Figure 2.5 VREG setup and mounting notes

Setup:

 

 

 

• Relationship between VREG and reference voltage

 

VREG =

R1 + R2

× (Reference voltage)

• • • • Equation (1)

R1

 

 

 

• Current consumption of division resistors

 

IREG =

VREG

 

• • • • Equation (2)

 

 

R1 + R2

 

Setup example:

• To output VREG = –18 V by four-time boosting if VI = –5 V and VO = –20 V

First, determine the total resistance of division resistors R1 and R2. If the current consumption is assumed to be 20 μA, the total resistance can be obtained from equation (2) as follows:

R1 + R2 = 12V ÷ 20 μA = 900 kΩ

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 kΩ

R2 = 825 kΩ

2–26

EPSON

S1F70000 Series Technical Manual