OM6211 데이터 시트보기 (PDF) - Philips Electronics
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OM6211 Datasheet PDF : 48 Pages
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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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