OM6211 View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

OM6211

48×84 dot matrix LCD driver

Philips Electronics 

Philips Semiconductors

48 × 84 dot matrix LCD driver

Product specification

OM6211

9.9 Bias system

The bias voltage levels are set in the ratio of

R - R - nR - R - R. Different multiplex rates require

different factors of n. This is programmed by BS2 to BS0.

For optimum bias values, n can be calculated from the

following equation:

n = Mux rate – 3 ; where Mux rate is 48.

Changing the bias system from the optimum setting will

have a consequence on the contrast and viewing angle.

One reason to depart from the optimum would be to

reduce the required VLCD voltage. A compromise between

contrast and VLCD must be found for any particular

application.

In the OM6211 one of three possible values of the bias

system can be selected. The value 1⁄7 is default.

Table 1 Programming the required bias system

BS2

BS1

BS0

0

1

1

1

0

0

1

0

1

n

BIAS MODE

TYPICAL MUX

RATES

4

1⁄8

1 : 55 and 1 : 48

3

1⁄7

1 : 33

2

1⁄6

1 : 24

Table 2 LCD bias voltages for 1⁄6 bias, 1⁄7 bias and 1⁄8 bias.

SYMBOL

V1

V2

V3

V4

V5

V6

FOR 1⁄6 BIAS

VLCD

5⁄6VLCD

4⁄6VLCD

2⁄6VLCD

1⁄6VLCD

VSS

BIAS VOLTAGE

FOR 1⁄7 BIAS

VLCD

6⁄7VLCD

5⁄7VLCD

2⁄7VLCD

1⁄7VLCD

VSS

FOR 1⁄8 BIAS

VLCD

7⁄8VLCD

6⁄8VLCD

2⁄8VLCD

1⁄8VLCD

VSS

9.10 Voltage multiplier control

The OM6211 incorporates a software configurable voltage multiplier. After reset (RES) the voltage multiplier is set to

4VDD2. Other voltage multiplier factors are set via the serial interface (S1 and S0).

Table 3 HV generator multiplication

S1

S0

0

0

0

1

1

0

1

1

MULTIPLICATION

2VDD2

3VDD2

4VDD2

not available

2002 Jan 17

10

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