pcf8536 NXP Semiconductors, pcf8536 Datasheet - Page 27

• Manufacturer Part Number: pcf8536
• Description: Universal Lcd Driver For Low Multiplex Rates Including A 6 Channel Pwm Generator
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Table 31.
[1]
[2]
[3]
PCF8536
Product data sheet
LCD multiplex
drive mode
1:4
1:4
1:4
1:6
1:6
1:6
1:8
1:8
1:8
[3]
[3]
[3]
[3]
[3]
Determined from
Determined from
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 V
Preferred LCD drive modes: summary of characteristics
Number of:
Backplanes
4
4
4
6
6
6
8
8
8
Equation
Equation
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 V
threshold voltage (V
the static drive mode, a suitable choice is V
Bias is calculated by
The RMS on-state voltage (V
where V
The RMS off-state voltage (V
Discrimination is the ratio of V
V
V
on RMS
off RMS
a = 1 for
a = 2 for
a = 3 for
n = 4 for 1:4 multiplex drive
n = 6 for 1:6 multiplex drive
n = 8 for 1:8 multiplex drive
6.
5.


LCD

LCD

Levels
3
4
5
3
4
5
3
4
5
.
=
=
1
1
1
⁄
⁄
⁄
V
2
3
4
is the resultant voltage at the LCD segment and where the values for n are
V
LCD
LCD
bias
bias
bias
All information provided in this document is subject to legal disclaimers.
----------------------------- -
n
----------------------------- -
n
LCD bias
configuration
1
1
1
1
1
1
1
1
1
a
a
⁄
⁄
⁄
⁄
⁄
⁄
⁄
⁄
⁄
Universal LCD low multiplex driver with 6 channel PWM generator
2
3
4
2
3
4
2
3
4
2


2
th(off)
+
–


------------ -
1
1
1
LCD
2a
2a
Rev. 1 — 6 October 2011
1
+
+
+
), typically when the LCD exhibits approximately 10 % contrast. In
a
+
+
a
a
is determined by equating V

, where the values for a are
n

n
2
2
on(RMS)
off(RMS)
on(RMS)
0.433
0.333
0.331
0.456
0.333
0.306
0.467
0.333
0.293
V
---------------------- -
off RMS
) for the LCD is calculated with
V
) for the LCD is calculated with
LCD
to V

off(RMS)

LCD
0.661
0.577
0.545
0.612
0.509
0.467
0.586
0.471
0.424
V
----------------------
on RMS
V
> 3V
LCD
and is determined from

th(off)

off(RMS)
.
1.527
1.732
1.646
1.341
1.527
1.527
1.254
1.414
1.447
D
=
with a defined LCD
V
---------------------- -
V
off RMS
on RMS


Equation
Equation 4


[1]
PCF8536
© NXP B.V. 2011. All rights reserved.
Equation
V
2.309V
3.0V
3.024V
2.191V
3.0V
3.266V
2.138V
3.0V
3.411V
LCD
5:
off(RMS)
off(RMS)
off(RMS)
[2]
off(RMS)
off(RMS)
off(RMS)
off(RMS)
off(RMS)
off(RMS)
6:
27 of 74
(4)
(5)