SCI7654 データシートの表示（PDF） - Seiko Epson Corp

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SCI7654

DC/DC Converter

Seiko Epson Corp 

SCI7654M0A/C0A

FUNCTIONAL DESCRIPTION

Clock Generator Circuit

As the SCI7654 has a built-in clock generator circuit, it requires no external source at all. The clock rate changes

depending on the FC pin signal level, and the Low Output or High Output mode can be selected. This allows

a frequency selection according to the current capacitance and load current when the booster output impedance

changes depending on the clock rate and external booster capacitance.

FC pin

H (VDD)

L (VIN)

Mode

Low Output

High Output

Clock Rate

4.0 kHz (Typ.)

16.0 kHz (Typ.)

Current Consumption

IOP

Approx. 4 times of IOP

Output Ripple

VRP

Approx. 1/4 time of VRI

Voltage Converter Circuit

The voltage converter receives a clock from the clock generator, and boosts the VIN input power voltage

quadruple, triple or double. Four converter circuits are required for quadruple boosting, three converts are

required for triple boosting, and dual converters are required for double boosting.

VDD

(0V)

VIN

10V

(-5V)

double boosting

15V

-10V

triple boosting

-15V

20V

-20V

quadruple boosting

Voltage step-up diagram (during -5V input)

Reference Voltage Circuit

The SCI7654 has a built-in reference voltage circuit for the voltage regulator. The temperature coefficient of

reference voltage can be changed using pins TC1 and TC2, and a voltage having one of four types of temperature

gradients can be output at VREG pin for LCD driving.

Mode

CT0

CT1

CT2

CT3

TC1

H(VDD)

H

L(VIN)

L

TC2

H(VDD)

L(VIN)

H

L

Reference Voltage, VREF (V)

Min.

Typ.

Max.

-1.55

-1.5

-1.45

-1.70

-1.5

-1.30

-1.90

-1.5

-1.10

-2.15

-1.5

-0.85

Temperature Coefficient, CT (%/˚C)

Min.

Typ.

Max.

-0.07

-0.04

0

-0.25

-0.15

-0.07

-0.45

-0.35

-0.20

-0.75

-0.55

-0.30

5

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