PCA9533_3

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 03 — 27 April 2009

6 of 24

NXP Semiconductors

PCA9533

6.3.4 PCS1 - Frequency Prescaler 1

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

The period of BLINK1 = (PSC1 + 1) / 152.

6.3.5 PWM1 - Pulse Width Modulation 1

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

when the count is less than the value in PWM1 and HIGH (LED off) when it is greater. If

PWM1 is programmed with 00h, then the PWM1 output is always HIGH (LED off).

The duty cycle of BLINK1 = PWM1 / 256.

6.3.6 LS0 - LED selector

The LSn LED selector register determines the source of the LED data.

00 = output is set high-impedance (LED off; default)

01 = output is set LOW (LED on)

10 = output blinks at PWM0 rate

11 = output blinks at PWM1 rate

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

00000000

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

Table 10.

LS0 - LED selector register bit description

Legend: * default value.

Register

Bit

Value

Description

LS0

7:6

00*

LED3 selected

5:4

00*

LED2 selected

3:2

00*

LED1 selected

1:0

00*

LED0 selected