STE2004 Datasheet, PDF (8/66 Pages) STMicroelectronics – 102 X 65 SINGLE CHIP LCD CONTROLLER / DRIVER

STE2004
Table 3.
BS2
BS1
BS0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
The following table Bias Level for m = 65 and m = 49 are provided:
Table 4.
Symbol
V1
V2
V3
V4
V5
V6
m = 65 (1/9)
V_LCD
8/9*V_LCD
7/9*V_LCD
2/9*V V_LCD
1/9 *V_LCD
V_SS
n
7
6
5
4
3
2
1
0
m = 49 (1/8)
V_LCD
7/8*V_LCD
6/8*V_LCD
2/8*V_LCD
1/8*V_LCD
V_SS
3.6 LCD Voltage Generation
The LCD Voltage at reference temperature (To = 27°C) can be set using the VOP register content according to
the following formula:
V_LCD(T=To) = V_LCDo = (Ai+V_OP · B) (i=0,1,2)
with the following values:
Symbol
Ao
A1
A2
B
To
Value
2.95
6.83
10.71
0.0303
27
Unit
Note
V
PRS = [0;0]
V
PRS = [0;1]
V
PRS = [1;0]
V
°C
Note that the three PRS values produce three adjacent ranges for VLCD. If the V_OP register and PRS bits
are set to zero the internal voltage generator is switched off.
The proper value for the VLCD is a function of the Liquid Crystal Threshold Voltage (Vth) and of the Mul-
tiplexing Rate. A general expression for this is:
V_LCD
=
---------¹-----+---------^m------------
2 ⋅ _1 – ----¹-_m---_
⋅
V_th
For MUX Rate m = 65 the ideal V_LCD is:
V_LCD(to) = 6.85 · V_th
than:
V_op
=
(_---6_---._--8_---5_-----⋅_---V_{----t--h----–-----}A_----i--)
0.03
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