pcf8536 NXP Semiconductors, pcf8536 Datasheet - Page 18

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

NXP Semiconductors
PCF8536
Product data sheet
8.1.10 Command: frame-frequency-PWM
With the frame-frequency-PWM command, the frame frequency for the PWM signal can
be set.
The PWM system requires a clock of 230 kHz either internally generated or externally
supplied. Using a slower clock may result in visible flickering of LEDs driven with the PWM
signal.
When EFR is set to 230 kHz, then the PWM frame frequency will be calculated with
Equation
where p is the frequency divide factor (see
Table 22.
Table 23.
[1]
[2]
In order to avoid flickering caused by the interaction of the backlight LED and the LCD
frame frequency, the PWM frame frequency should be programmed to be more than
50 Hz different from LCD frame frequency or multiples of the LCD frame frequency (see
Figure 8
f
Bit
7 to 4
3 to 0
FP[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
PWM
Nominal frame frequency calculated for the default clock frequency of 230 kHz.
Default value.
[2]
=
f
---------------- -
Symbol
-
FP[3:0]
128 p 
and
clk ext
3:
Frame-frequency-PWM - PWM frame frequency command bit description
PWM frame frequency prescaler values for 230 kHz clock operation

Table 49 on page

All information provided in this document is subject to legal disclaimers.
Universal LCD low multiplex driver with 6 channel PWM generator
Nominal PWM frame frequency (Hz)
59.9
69.1
81.7
89.8
99.8
112.3
119.8
128.3
138.2
149.7
163.4
179.7
199.7
224.6
256.7
299.5
Rev. 1 — 6 October 2011
Value
0100
see
68).
Table 23
Table
Description
fixed value
frequency prescaler
23).
[1]
Divide factor, p
30
26
22
20
18
16
15
14
13
12
11
10
9
8
7
6
PCF8536
© NXP B.V. 2011. All rights reserved.
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