PCA9552_5

© Koninklijke Philips Electronics N.V. 2006. All rights reserved.

Product data sheet

Rev. 05 — 9 March 2006

7 of 28

Philips Semiconductors

PCA9552

6.3.3 PCS0 - Frequency Prescaler 0

PSC0 is used to program the period of the PWM output.

The period of BLINK0 = (PSC0 + 1) / 44.

6.3.4 PWM0 - Pulse Width Modulation 0

The PWM0 register determines the duty cycle of BLINK0. The outputs are LOW (LED off)

when the count is less than the value in PWM0 and HIGH when it is greater. If PWM0 is

programmed with 00h, then the PWM0 output is always LOW.

The duty cycle of BLINK0 = (256

− PWM0) / 256.

6.3.5 PCS1 - Frequency Prescaler 1

PSC1 is used to program the period of the PWM output.

The period of BLINK1 = (PSC1 + 1) / 44.

6.3.6 PWM1 - Pulse Width Modulation 1

The PWM1 register determines the duty cycle of BLINK1. The outputs are LOW (LED off)

when the count is less than the value in PWM1 and HIGH when it is greater. If PWM1 is

programmed with 00h, then the PWM1 output is always LOW.

The duty cycle of BLINK1 = (256

− PWM1) / 256.

Table 6:

PSC0 - Frequency Prescaler 0 register description

Bit

7

6

5

4

3

2

1

0

Symbol

PSC0[7]

PSC0[6]

PSC0[5]

PSC0[4]

PSC0[3]

PSC0[2]

PSC0[1]

PSC0[0]

Default

11111111

Table 7:

PWM0 - Pulse Width Modulation 0 register description

Bit

7

6

5

4

3

2

1

0

Symbol

PWM0

[7]

PWM0

[6]

PWM0

[5]

PWM0

[4]

PWM0

[3]

PWM0

[2]

PWM0

[1]

PWM0

[0]

Default

10000000

Table 8:

PSC1 - Frequency Prescaler 1 register description

Bit

7

6

5

4

3

2

1

0

Symbol

PSC1[7]

PSC1[6]

PSC1[5]

PSC1[4]

PSC1[3]

PSC1[2]

PSC1[1]

PSC1[0]

Default

11111111

Table 9:

PWM1 - Pulse Width Modulation 1 register description

Bit

7

6

5

4

3

2

1

0

Symbol

PWM1

[7]

PWM1

[6]

PWM1

[5]

PWM1

[4]

PWM1

[3]

PWM1

[2]

PWM1

[1]

PWM1

[0]

Default

10000000