PCA8538UG(2014) View Datasheet(PDF) - NXP Semiconductors.
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MFG CO.
PCA8538UG Datasheet PDF : 107 Pages
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NXP Semiconductors
PCA8538
Automotive 102 x 9 Chip-On-Glass LCD segment driver
Table 36. LCD drive modes: summary of characteristics
LCD drive
Number of:
LCD bias
V----o---f--f---R---M-----S--
mode
Backplanes Levels configuration
VLCD
static
1
2
static
0
1:2 multiplex 2
1:2 multiplex 2
1:2 multiplex[3] 2
1:4 multiplex[3] 4
1:4 multiplex 4
1:4 multiplex 4
1:6 multiplex[3] 6
1:6 multiplex 6
1:6 multiplex 6
1:8 multiplex[3] 8
1:8 multiplex 8
1:8 multiplex 8
1:9 multiplex[3] 9
1:9 multiplex 9
1:9 multiplex 9
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
3
1⁄2
4
1⁄3
5
1⁄4
3
1⁄2
4
1⁄3
5
1⁄4
0.354
0.333
0.395
0.433
0.333
0.331
0.456
0.333
0.306
0.467
0.333
0.293
0.471
0.333
0.289
V----o---n-----R---M----S---
VLCD
1
0.791
0.745
0.729
0.661
0.577
0.545
0.612
0.509
0.467
0.586
0.471
0.424
0.577
0.454
0.408
D = -V----o--n-----R---M----S--- [1]
VoffRMS
VLCD[2]
2.236
2.236
1.845
1.527
1.732
1.646
1.341
1.527
1.527
1.254
1.414
1.447
1.225
1.374
1.414
Von(RMS)
2.828 Voff(RMS)
3.0 Voff(RMS)
2.529 Voff(RMS)
2.309 Voff(RMS)
3.0 Voff(RMS)
3.024 Voff(RMS)
2.191 Voff(RMS)
3.0 Voff(RMS)
3.266 Voff(RMS)
2.138 Voff(RMS)
3.0 Voff(RMS)
3.411 Voff(RMS)
2.121 Voff(RMS)
3.000 Voff(RMS)
3.464 Voff(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 power saving from a reduction of VLCD.
Intermediate LCD biasing voltages are obtained from an internal voltage divider. The
biasing configurations that apply to the preferred modes of operation, together with the
biasing characteristics as functions of VLCD and the resulting discrimination ratios (D), are
given in Table 36. 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.
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:
PCA8538
Product data sheet
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 = 1 for static mode
All information provided in this document is subject to legal disclaimers.
Rev. 4 — 26 September 2014
© NXP Semiconductors N.V. 2014. All rights reserved.
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