PCA9533 Datasheet, PDF (5/24 Pages) NXP Semiconductors – 4-bit I2C LED dimmer

NXP Semiconductors
PCA9533
4-bit I²C-bus LED dimmer
6.2.1 Control register definition
Table 4. Register summary
B2 B1 B0 Symbol
0
0
0
INPUT
0
0
1
PSC0
0
1
0
PWM0
0
1
1
PSC1
1
0
0
PWM1
1
0
1
LS0
Access
read only
read/write
read/write
read/write
read/write
read/write
Description
input register
frequency prescaler 0
PWM register 0
frequency prescaler 1
PWM register 1
LED selector
6.3 Register descriptions
6.3.1 INPUT - Input register
The INPUT register reflects the state of the device pins. Writes to this register will be
acknowledged but will have no effect.
Table 5.
Bit
Symbol
Default
INPUT - Input register description
7
6
5
4
-
-
-
-
0
0
0
0
3
LED3
X
2
LED2
X
1
LED1
X
0
LED0
X
Remark: The default value ‘X’ is determined by the externally applied logic level (normally
logic 1) when used for directly driving LED with pull-up to V_DD.
6.3.2 PCS0 - Frequency Prescaler 0
PSC0 is used to program the period of the PWM output.
The period of BLINK0 = (PSC0 + 1) / 152.
Table 6.
Bit
Symbol
Default
PSC0 - Frequency Prescaler 0 register description
7
6
5
4
3
2
PSC0[7] PSC0[6] PSC0[5] PSC0[4] PSC0[3] PSC0[2]
0
0
0
0
0
0
1
PSC0[1]
0
0
PSC0[0]
0
6.3.3 PWM0 - Pulse Width Modulation 0
The PWM0 register determines the duty cycle of BLINK0. The outputs are LOW (LED on)
when the count is less than the value in PWM0 and HIGH (LED off) when it is greater. If
PWM0 is programmed with 00h, then the PWM0 output is always HIGH (LED off).
The duty cycle of BLINK0 = PWM0 / 256.
Table 7.
Bit
Symbol
Default
PWM0 - Pulse Width Modulation 0 register description
7
6
5
4
3
2
PWM0 PWM0 PWM0 PWM0 PWM0 PWM0
[7]
[6]
[5]
[4]
[3]
[2]
1
0
0
0
0
0
1
PWM0
[1]
0
0
PWM0
[0]
0
PCA9533_3
Product data sheet
Rev. 03 — 27 April 2009
© NXP B.V. 2009. All rights reserved.
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