JBT6K49-AS

2002-03-12

9

Description of Functions and Operation

DC-DC converter

The JBT6K49-AS generates an analog supply voltage for the source driver (T6K47) and an LCD-driving

voltage for the gate driver (T6K48). The DC-DC converter consists of three circuit blocks which output +4.8 V,

+13.0 V and -13.0 V. The ways in which the DC-DC converter can be used are shown below.

Note 2: Connect a voltage boosting kick capacitor or capacitors to each circuit block. Normally the capacitance of

the kick capacitor should be 1.0

mF. Connect a 10 mF capacitor across the boosted-voltage output pin and

the VSS pin of DC-DC converter (1), since the voltage generated in the DC-DC converter is unstable. In

addition, connect a 1

converter (1).

Oscillation Circuit

The JBT6K49-AS generates the clock pulse used by the DC-DC converter. The FSEL1 and FSEL2 pins can be

used to select the clock oscillation frequency. The following table lists the correspondence between the pin

settings and the selected frequency.

FSEL2

FSEL1

Oscillation Frequency (initial value)

0

0

3.5 kHz

0

1

5.0 kHz

1

0

7.0 kHz

1

1

10.0 kHz

Note 3: The relationship of the oscillation frequency and the oscillation resistance depends on assembly and

measuring conditions.

Therefore, select the oscillation resistance after enough evaluating.

DC-DC converter (1):

Generates

+4.8 V.

CA1

-

CA1

+

CA2

-

CA2

+

CB1

-

CB1

+

CB5

-

CB5

+

CC1

-

CC1

+

DC-DC converter (1):

Generates

+13.0 V.

DC-DC converter (1):

Generates

-13.0 V.