STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL, PWM CONTROL SWITCHING REGULATOR CONTROLLER

S-8333 Series

13

5. Error amplifier

The error amplifier outputs the PWM control signal so that the voltage of the FB pin is held at a specific value

(1 V). By connecting a resistor (RZ) and capacitor (CZ) to the output pin (CC pin) of the error amplifier in series,

an optional loop gain can be set, enabling stabilized phase compensation.

6. Operation

The following are basic equations [(1) through (7)] of the step-up switching regulator (refer to Figure 10).

D

L

M1

FB

CONT

EXT

VSS

Figure 10 Step-up Switching Regulator Circuit for Basic Equations

*1.

L

V

V

L

V

dt

dl

S

IN

L

L

−

=

=

.............................................................................................................................(2)

Integration of the above equation:

t

L

V

V

I

S

IN

L

×













−

=

.................................................................................................................................. (3)

ON

S

IN

PK

t

L

V

V

I

×













−

=

........................................................................................................................... (4)

The energy stored in L is represented by

1

(

)

IN

2

*

D

OUT

L

V

V

V

V

−

+

=

......................................................................................................................... (5)

*2.