PCA85133USLASH2DASLASHQ1 datasheet(7/44 Pages) NXP

7 / 44 page

PCA85133_1

Product data sheet

Rev. 1 — 23 October 2009

7 of 44

NXP Semiconductors

PCA85133

Universal LCD driver for low multiplex rates

Bias is calculated by

, where the values for a are

a = 1 for 1

⁄2 bias

a = 2 for 1

⁄3 bias

The RMS on-state voltage (Von(RMS)) for the LCD is calculated with Equation 1

(1)

where the values for n are

n = 1 for static mode

n = 2 for 1:2 multiplex

n = 3 for 1:3 multiplex

n = 4 for 1:4 multiplex

The RMS off-state voltage (Voff(RMS)) for the LCD is calculated with Equation 2:

(2)

Discrimination is the ratio of Von(RMS) to Voff(RMS) and is determined from Equation 3:

(3)

Using Equation 3, the discrimination for an LCD drive mode of 1:3 multiplex with

⁄

2 bias is

and the discrimination for an LCD drive mode of 1:4 multiplex with

⁄2 bias is

The advantage of these LCD drive modes is a reduction of the LCD full scale voltage VLCD

as follows:

• 1:3 multiplex (1

⁄

2 bias):

• 1:4 multiplex (1

⁄2 bias):

These compare with

when 1

⁄

3 bias is used.

It should be noted that VLCD is sometimes referred as the LCD operating voltage.

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

on RMS

()

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

LCD

off RMS

()

–

()

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

LCD

on RMS

()

off RMS

()

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

()

–

()

–

()

–

()

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

1.732

----------

1.528

LCD

off RMS

()

2.449V

off RMS

()

LCD

()

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

2.309V

off RMS

()

LCD

off RMS

()

PCA85133U/2DA/Q1 Datasheet(PDF) 7 Page - NXP Semiconductors

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