PCF8536AT/1 View Datasheet(PDF) - NXP Semiconductors.

Part Name

Description

MFG CO.

PCF8536AT/1

Universal LCD driver for low multiplex rates including a 6 channel PWM generator

NXP Semiconductors. 

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NXP Semiconductors

PCF8536

Universal LCD low multiplex driver with 6 channel PWM generator

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 3:

fPWM

=

f--c---l-k----e---x--t--

128  p

(3)

where p is the frequency divide factor (see Table 23).

Table 22. Frame-frequency-PWM - PWM frame frequency command bit description

Bit

Symbol

Value

Description

7 to 4 -

0100

fixed value

3 to 0 FP[3:0]

see Table 23 frequency prescaler

Table 23.

FP[3:0]

0000

0001

0010

0011

0100

0101

0110

0111[2]

1000

1001

1010

1011

1100

1101

1110

1111

PWM frame frequency prescaler values for 230 kHz clock operation

Nominal PWM frame frequency (Hz)[1]

Divide factor, p

59.9

30

69.1

26

81.7

22

89.8

20

99.8

18

112.3

16

119.8

15

128.3

14

138.2

13

149.7

12

163.4

11

179.7

10

199.7

9

224.6

8

256.7

7

299.5

6

[1] Nominal frame frequency calculated for the default clock frequency of 230 kHz.

[2] Default value.

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 and Table 49 on page 68).

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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