PCF8536AT/1 View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
PCF8536AT/1
NXP Semiconductors.
'PCF8536AT/1' PDF : 74 Pages View PDF
NXP Semiconductors
PCF8536
Universal LCD low multiplex driver with 6 channel PWM generator
Discrimination is a term which is defined as the ratio of the on and off RMS voltage across
a segment. It can be thought of as a measurement of contrast.
Table 31. Preferred LCD drive modes: summary of characteristics
LCD multiplex Number of:
LCD bias
drive mode
Backplanes Levels configuration
V----o---f--f---R----M----S--
VLCD
1:4 [3]
4
1:4
4
1:4 [3]
4
1:6 [3]
6
1:6
6
1:6
6
1:8 [3]
8
1:8 [3]
8
1:8
8
3
1⁄2
4
1⁄3
5
1⁄4
3
1⁄2
4
1⁄3
5
1⁄4
3
1⁄2
4
1⁄3
5
1⁄4
0.433
0.333
0.331
0.456
0.333
0.306
0.467
0.333
0.293
V----o---n-----R---M----S---
VLCD
0.661
0.577
0.545
0.612
0.509
0.467
0.586
0.471
0.424
D = -V----o--n-----R---M----S--- [1] VLCD[2]
VoffRMS
1.527
1.732
1.646
1.341
1.527
1.527
1.254
1.414
1.447
2.309Voff(RMS)
3.0Voff(RMS)
3.024Voff(RMS)
2.191Voff(RMS)
3.0Voff(RMS)
3.266Voff(RMS)
2.138Voff(RMS)
3.0Voff(RMS)
3.411Voff(RMS)
[1] Determined from Equation 6.
[2] Determined from Equation 5.
[3] In these examples, the discrimination factor and hence the contrast ratios are smaller. The advantage of these LCD drive modes is a
reduction of the LCD voltage VLCD.
A practical value for VLCD is determined by equating Voff(RMS) with a defined LCD
threshold voltage (Vth(off)), typically when the LCD exhibits approximately 10 % contrast. In
the static drive mode, a suitable choice is VLCD > 3Vth(off).
Bias is calculated by -----1------- , where the values for a are
1+a
a = 1 for 1⁄2 bias
a = 2 for 1⁄3 bias
a = 3 for 1⁄4 bias
The RMS on-state voltage (Von(RMS)) for the LCD is calculated with Equation 4
VonRMS
=
VLCD
--a---2----+-----2---a----+-----n---
n 1 + a2
(4)
where VLCD is the resultant voltage at the LCD segment and where the values for n are
n = 4 for 1:4 multiplex drive
n = 6 for 1:6 multiplex drive
n = 8 for 1:8 multiplex drive
The RMS off-state voltage (Voff(RMS)) for the LCD is calculated with Equation 5:
VoffRMS
=
VLCD
--a---2----–----2----a----+-----n---
n 1 + a2
(5)
Discrimination is the ratio of Von(RMS) to Voff(RMS) and is determined from Equation 6:
PCF8536
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 6 October 2011
© NXP B.V. 2011. All rights reserved.
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