STE2001 Datasheet, PDF (14/36 Pages) STMicroelectronics – 65 X 128 SINGLE CHIP LCD CONTROLLER / DRIVER

STE2001
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:
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
Temperature Coefficient
As the viscosity, and therefore the contrast, of the LCD are subject to change with temperature, there’s the need
to vary the LCD Voltage with temperature. The STE2001 provides the possibility to change the VLCD in a linear
fashion against temperature with four different Temperature Coefficient selectable through the TC0 and TC1
bits.
TC1
TC0
Value
0
0
-550
0
1
-1350
1
0
-1650
1
1
-2650
Figure 14. VLCD Slopes Cross Point with Different TC
Unit
PPM/°C
PPM/°C
PPM/°C
PPM/°C
V_LCD
D01IN1256/mod
35ºC
TEMP
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