STE2001

14/36

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:

than:

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.

Figure 14. VLCD Slopes Cross Point with Different TC

TC1

TC0

Value

Unit

0

0

-550

PPM/

°C

0

1

-1350

PPM/

°C

1

0

-1650

PPM/

°C

1

1

-2650

PPM/

°C

V

LCD

1m

+

21

1

m

---------

–





⋅

------------------------------------ V

th

⋅

=

V

op

6.85 V

th

A

i

–

⋅

()

0.03

-----------------------------------------

=

35ºC

TEMP

D01IN1256/mod