pcf8536 NXP Semiconductors, pcf8536 Datasheet - Page 68

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

18. Appendix: possible PWM and LCD frame frequency combinations to avoid flicker
Table 49.
Experiments have shown that likely no flicker occurs when PWM frame frequency and LCD frame frequency are between 40 Hz and 50 Hz apart
and no flicker occurs if they are more than 50 Hz apart.
[1]
frame frequencies
LCD (f
59.9
70.5
79.9
90.4
99.8
108.9
119.8
129.5
140.9
149.7
159.7
171.1
177.5
184.3
191.7
199.7
208.3
217.8
228.2
239.6
252.2
266.2
281.9
299.5
The table shows the smallest distance (f) from one frequency to the next or multiples of the next. f = MIN(f1  n  f2); the values for n are 1 to 6; f1 and f2 can be either f
f
fr(LCD)
fr(LCD)
; both relationships have to be considered. A PWM frame frequency (f
LCD and PWM frame frequency combinations to avoid flicker
)
59.9
0.0
10.6
20.0
29.4
20.0
10.9
0.0
9.7
21.1
29.9
20.0
8.6
2.2
4.6
12.0
20.0
28.6
21.8
11.4
0.0
12.6
26.6
17.6
0.0
69.1
9.2
1.4
10.8
21.3
30.7
29.3
18.4
8.7
2.7
11.5
21.5
32.9
29.9
23.0
15.7
7.7
1.0
10.5
20.8
32.3
24.2
10.2
5.4
23.0
81.7
21.8
1.8
8.7
18.2
27.2
38.1
33.8
22.4
13.6
3.6
7.8
14.1
20.9
28.3
27.2
16.9
5.4
7.2
21.2
36.8
27.2
11.2
36.3
36.7
89.8
29.9
19.4
10.0
0.6
10.0
19.1
29.9
39.7
38.8
29.9
20.0
8.6
2.2
4.6
12.0
20.0
28.6
38.1
41.4
29.9
17.3
3.3
12.3
29.9
99.8
20.0
29.4
20.0
9.4
0.0
9.1
20.0
29.7
41.1
49.9
39.9
28.5
22.2
15.4
8.0
0.0
8.7
18.2
28.5
39.9
47.3
33.3
17.6
0.0
112.3
7.5
28.6
32.4
21.9
12.5
3.4
7.5
17.2
28.6
37.4
47.4
53.5
47.1
40.3
32.9
25.0
16.3
6.8
3.6
15.0
27.6
41.6
55.1
37.4
PWM
119.8
0.0
21.1
39.9
29.4
20.0
10.9
0.0
9.7
21.1
29.9
39.9
51.3
57.7
55.3
47.9
39.9
31.3
21.8
11.4
0.0
12.6
26.6
42.3
59.9
) of less than 60 Hz may show flicker purely from the LCD.
[1]
128.3
8.6
12.6
31.4
37.9
28.5
19.4
8.6
1.2
12.6
21.4
31.4
42.8
49.1
55.9
63.3
57.0
48.4
38.9
28.5
17.1
4.5
9.5
25.2
42.8
PWM (f
138.2
18.4
2.7
21.5
42.6
38.4
29.3
18.4
8.7
2.7
11.5
21.5
32.9
39.2
46.1
53.4
61.4
68.1
58.6
48.3
36.9
24.2
10.2
5.4
23.0
PWM
)
149.7
29.9
8.8
10.0
31.1
49.9
40.8
29.9
20.2
8.8
0.0
10.0
21.4
27.7
34.6
41.9
49.9
58.6
68.1
71.3
59.9
47.3
33.3
17.6
0.0
163.4
22.4
3.6
17.5
36.3
54.5
43.6
33.8
22.4
13.6
3.6
20.9
28.3
36.3
45.0
54.5
64.8
76.2
74.5
60.5
44.8
27.2
16.3
7.8
14.1
179.7
0.0
31.7
20.0
1.1
20.0
38.1
59.9
50.2
38.8
29.9
20.0
8.6
2.2
4.6
12.0
20.0
28.6
38.1
48.5
59.9
72.5
86.5
77.5
59.9
199.7
20.0
11.7
39.9
18.8
0.0
18.2
39.9
59.4
58.7
49.9
39.9
28.5
22.2
15.4
8.0
0.0
8.7
18.2
28.5
39.9
52.5
66.6
82.2
99.8
224.6
15.0
13.2
15.0
43.8
25.0
6.8
15.0
34.4
57.3
74.9
64.9
53.5
47.1
40.3
32.9
25.0
16.3
6.8
3.6
15.0
27.6
41.6
57.3
74.9
256.7
17.1
25.2
17.1
14.5
42.8
38.9
17.1
2.3
25.2
42.8
62.7
85.6
79.2
72.4
65.0
57.0
48.4
38.9
28.5
17.1
4.5
9.5
25.2
42.8
299.5
0.0
17.6
20.0
28.3
0.0
27.2
59.9
40.5
17.6
0.0
20.0
42.8
55.5
69.1
83.9
99.8
91.1
81.7
71.3
59.9
47.3
33.3
17.6
0.0
PWM
or