3

A011706

Pin Configuration

Pin

Name Description

Inductor pin

2

GND

Ground pin

3

Input voltage supply pin. It is common practice to use a bypass

capacitor as close as possible to the device on this pin.

4

SDI

Serial data input pin

5

SCK

Serial clock input pin

6

EL1

EL lamp 1 pin

7

EL2

EL lamp 2 pin

8

EL3

EL lamp 3 pin

9

COM

Common pin for one side of all 3 EL lamps

10

High Voltage capacitor pin

Logic Input Conditions

The serial data input consists of a 10-bit string, 3-bits of bright-

converter. The power converter runs if any of the EL lamps has a

non-zero brightness value or if the PWR_ON bit is high while the

other 9 bits are low.

1.

SDI may be H or L if SCK is H.

2.

SCK may be H or L if SDI is H.

3.

While inputting serial data to the shift register, SDI can

change value only when SCK is L.

4.

The previous 10 bits of serial input will be latched when

SDI makes L to H transition while SCK is H.

EL Lamp Brightness Control

The EL Lamp brightness control is a 3-bit binary number stored

in a latch, which is provided by a serial to parallel conversion shift

register.

1.

If all the 3 bits for a designated EL lamp are L, the differential

voltage across that lamp will be zero.

2.

If any of the 3 bits for a designated EL lamp is H:

a.

The 3-bit value sets the average number of cycles

for which the EL lamp voltage is non-zero.

b.

The EL lamp brightness is linearly proportional

to the binary lamp control code.

Logic Input Diagram

S1

S2

S3

S4

S5

S6

S7

S8

S9

S10

SDI

SCK

EL 1 Control

Latches

in Data

MSB of

EL1

LSB of

EL1

MSB of

EL2

LSB of

EL2

MSB of

EL3

LSB of

EL3

PWR_ON

EL 2 Control

EL 3 Control

Note:

1. Serial data is latched when SDI makes L to H transition and while SCK is H.

2. S1 is the first serial data input being fed.

HV858