PCF8533 View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'PCF8533' PDF : 45 Pages View PDF
NXP Semiconductors
PCF8533
Universal LCD driver for low multiplex rates
n = 1 for static drive mode
n = 2 for 1:2 multiplex drive mode
n = 3 for 1:3 multiplex drive mode
n = 4 for 1:4 multiplex drive mode
The RMS off-state voltage (Voff(RMS)) for the LCD is calculated with Equation 2:
Voff(RMS)
=
VLCD
--a---2----–----2----a----+-----n---
n × (1 + a)2
(2)
Discrimination is the ratio of Von(RMS) to Voff(RMS) and is determined from Equation 3:
D
=
-V----o---n--(--R---M----S---)
Voff(RMS)
=
(---a-----+-----1----)--2----+-----(--n-----–----1----)
(a – 1)2 + (n – 1)
(3)
Using Equation 3, the discrimination for an LCD drive mode of 1:3 multiplex with
1⁄2 bias is 3 = 1.732 and the discrimination for an LCD drive mode of 1:4 multiplex with
1⁄2 bias is
-----2---1--
3
=
1.528 .
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): VLCD = 6 × Voff(RMS) = 2.449Voff(RMS)
• 1:4 multiplex (1⁄2 bias): VLCD =
(---4-----×---------3----)
3
= 2.309Voff(RMS)
These compare with VLCD = 3Voff(RMS) when 1⁄3 bias is used.
It should be noted that VLCD is sometimes referred as the LCD operating voltage.
PCF8533_4
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 04 — 5 March 2010
© NXP B.V. 2010. All rights reserved.
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