STE2004SDIE2 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
STE2004SDIE2 Datasheet PDF : 79 Pages
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Circuit description
Table 3. Bias level m=65 and m=49
Symbol
m = 65 (1/9)
V1
VLCD
V2
8/9*VLCD
V3
7/9*VLCD
V4
2/9*V VLCD
V5
1/9 *VLCD
V6
VSS
STE2004S
m = 49 (1/8)
VLCD
7/8*VLCD
6/8*VLCD
2/8*VLCD
1/8*VLCD
VSS
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:
VLCD(T=To) = VLCDo = (Ai+VOP · B)
with the following values:
(i=0,1,2)
Table 4. LCD voltage generation
Symbol
Value
Unit
Note
Ao
2.95
V
PRS = [0;0]
A1
6.83
V
PRS = [0;1]
A2
10.71
V
PRS = [1;0]
B
0.0303
V
To
27
°C
Note that the three PRS values produce three adjacent ranges for VLCD. If the VOP 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 multiplexing rate. A general expression for this is:
VLCD
=
-----------1----+----------m------------- ⋅
2⋅
⎛
⎝
1
–
---1--m---⎠⎞
Vth
For MUX Rate m = 65 the ideal VLCD is:
VLCD(to) = 6.85 · Vth
than:
Vop
=
(---6---.--8---5-----⋅------V----t--h-----–-----A----i--)
0.03
12/79
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