INTEGRATED CIRCUITS
PCA9533
4-bit I
2
C LED dimmer
Product data sheet
Supersedes data of 2003 Sep 19
2004 Oct 01
Philips
Semiconductors
Philips Semiconductors
Product data sheet
4-bit I
2
C LED dimmer
PCA9533
the duty cycle to vary the amount of time the LED is on and thus the
average current through the LED.
The initial setup sequence programs the two blink rates/duty cycles
for each individual PWM. From then on, only one command from the
bus master is required to turn individual LEDs ON, OFF, BLINK
RATE 1 or BLINK RATE 2. Based on the programmed frequency
and duty cycle, BLINK RATE 1 and BLINK RATE 2 will cause the
LEDs to appear at a different brightness or blink at periods up to
1.69 second. The open drain outputs directly drive the LEDs with
maximum output sink current of 25 mA per bit and 100 mA per
package.
To blink LEDs at periods greater than 1.69 second the bus master
(MCU, MPU, DSP, chipset, etc.) must send repeated commands to
turn the LED on and off as is currently done when using normal I/O
Expanders like the Philips PCF8574 or PCA9554. Any bits not used
for controlling the LEDs can be used for General Purpose Parallel
Input/Output (GPIO) expansion which provides a simple solution
when additional I/O is needed for ACPI power switches, sensors,
pushbuttons, alarm monitoring, fans, etc.
Power-On Reset (POR) initializes the registers to their default state
causing the bits to be set HIGH (LED off).
Due to pin limitations, the PCA9533 is not featured with hardware
address pins. The PCA9533/01 and the PCA9533/02 have different
fixed I
2
C addresses allowing operation of both on the same bus.
FEATURES
•
4 LED drivers (on, off, flashing at a programmable rate)
•
2 selectable, fully programmable blink rates (frequency and duty
cycle) between 0.591 Hz and 152 Hz (1.69 seconds and
6.58 milliseconds)
•
256 brightness steps
•
Input/outputs not used as LED drivers can be used as regular
GPIOs
•
Internal oscillator requires no external components
•
I
2
C interface logic compatible with SMBus
•
Internal power-on reset
•
Noise filter on SCL/SDA inputs
•
4 open drain outputs directly drive LEDs to 25 mA
•
Edge rate control on outputs
•
No glitch on power-up
•
Supports hot insertion
•
Low stand-by current
•
Operating power supply voltage range of 2.3 V to 5.5 V
•
0 to 400 kHz clock frequency
•
ESD protection exceeds 2000 V HBM per JESD22-A114,
150 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101
PIN CONFIGURATION
LED0
LED1
LED2
V
SS
1
2
3
4
8
7
6
5
V
DD
SDA
SCL
LED3
SW01035
Figure 1. Pin configuration
•
Latch-up testing is done to JEDEC Standard JESD78 which
exceeds 100 mA
PIN DESCRIPTION
PIN
NUMBER
1
2
3
4
5
6
7
8
SYMBOL
LED0
LED1
LED2
V
SS
LED3
SCL
SDA
V
DD
FUNCTION
LED driver 0
LED driver 1
LED driver 2
Supply ground
LED driver 3
Serial clock line
Serial data line
Supply voltage
•
Packages offered: SO8, TSSOP8 (MSOP8)
DESCRIPTION
The PCA9533 is a 4-bit
and SMBus I/O expander optimized for
dimming LEDs in 256 discrete steps for Red/Green/Blue (RGB)
color mixing and back light applications.
The PCA9533 contains an internal oscillator with two user
programmable blink rates and duty cycles coupled to the output
PWM. The LED brightness is controlled by setting the blink rate high
enough (> 100 Hz) that the blinking cannot be seen and then using
I
2
C
2004 Oct 01
2
Philips Semiconductors
Product data sheet
4-bit I
2
C LED dimmer
PCA9533
ORDERING INFORMATION
PACKAGES
8-Pin Plastic SO
8-Pin Plastic SO
8-Pin Plastic TSSOP
8-Pin Plastic TSSOP
TEMPERATURE RANGE
–40
°C
to +85
°C
–40
°C
to +85
°C
–40
°C
to +85
°C
–40
°C
to +85
°C
ORDER CODE
PCA9533D/01
PCA9533D/02
PCA9533DP/01
PCA9533DP/02
TOPSIDE MARK
P9533/1
P9533/2
P33/1
P33/2
DRAWING NUMBER
SOT96-1
SOT96-1
SOT505-1
SOT505-1
Standard packing quantities and other packaging data are available at www.standardproducts.philips.com/packaging.
I
2
C is a trademark of Philips Semiconductors Corporation.
BLOCK DIAGRAM
PCA9533
INPUT
REGISTER
SCL
INPUT
FILTERS
SDA
I
2
C-BUS
CONTROL
LED SELECT (LSx)
REGISTER
0
1
V
DD
POWER-ON
RESET
PRESCALER 0
REGISTER
OSCILLATOR
PRESCALER 1
REGISTER
PWM0
REGISTER
PWM1
REGISTER
LEDx
BLINK0
BLINK1
V
SS
SW02046
NOTE:
ONLY ONE I/O SHOWN FOR CLARITY
Figure 2. Block diagram
2004 Oct 01
3
Philips Semiconductors
Product data sheet
4-bit I
2
C LED dimmer
PCA9533
DEVICE ADDRESSING
Following a START condition the bus master must output the
address of the slave it is accessing. The address of the PCA9533/01
is shown in Figure 3 and PCA9533/02 in Figure 4.
SLAVE ADDRESS
CONTROL REGISTER DEFINITION
B2
0
0
SW01037
B1
0
0
1
1
0
0
B0
0
1
0
1
0
1
REGISTER
NAME
INPUT
PSC0
PWM0
PSC1
PWM1
LS0
TYPE
READ
READ/
WRITE
READ/
WRITE
READ/
WRITE
READ/
WRITE
READ/
WRITE
REGISTER
FUNCTION
INPUT
REGISTER
FREQUENCY
PRESCALER 0
PWM
REGISTER 0
FREQUENCY
PRESCALER 1
PWM
REGISTER 1
LED SELECTOR
1
1
0
0
0
1
0
R/W
0
0
1
Figure 3. Slave address — PCA9533/01
SLAVE ADDRESS
1
1
0
0
0
1
1
R/W
1
SW01038
Figure 4. Slave address — PCA9533/02
The last bit of the address byte defines the operation to be
performed. When set to logic 1 a read is selected while a logic 0
selects a write operation.
REGISTER DESCRIPTION
INPUT — INPUT REGISTER
LED
3
bit
Default
7
0
6
0
5
0
4
0
3
X
LED
2
2
X
LED
1
1
X
LED
0
0
X
CONTROL REGISTER
Following the successful acknowledgement of the slave address,
the bus master will send a byte to the PCA9533 which will be stored
in the Control Register.
The INPUT register reflects the state of the device pins. Writes to
this register will be acknowledged but will have no effect.
NOTE:
The default value “X” is determined by the externally applied
logic level, normally ‘1’ when used for directly driving LED with
pull-up to V
DD
.
PSC0 — FREQUENCY PRESCALER 0
bit
default
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
0
0
0
0
AI
0
B2
B1
B0
REGISTER ADDRESS
RESET STATE: 00h
AUTO-INCREMENT FLAG
SW01034
PSC0 is used to program the period of the PWM output.
Figure 5. Control register
The period of BLINK0
+
The lowest 3 bits are used as a pointer to determine which register
will be accessed.
If the auto-increment flag is set, the three low order bits of the
Control Register are automatically incremented after a read or write.
This allows the user to program the registers sequentially. The
contents of these bits will rollover to ‘000’ after the last register is
accessed.
When auto-increment flag is set (AI = 1) and a read sequence is
initiated, the sequence must start by reading a register different from
the input register (B2 B1 B0
0
0 0 0).
Only the 3 least significant bits are affected by the AI flag.
Unused bits must be programmed with zeroes.
(PSC0
)
1)
152
5
0
4
0
3
0
2
0
1
0
0
0
PWM0 — PWM REGISTER 0
bit
default
7
1
6
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 is: PWM0
256
PSC1 — FREQUENCY PRESCALER 1
bit
default
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
0
PSC1 is used to program the period of PWM output.
The period of BLINK1
+
(PSC1
)
1)
152
2004 Oct 01
4
Philips Semiconductors
Product data sheet
4-bit I
2
C LED dimmer
PCA9533
PWM1 — PWM REGISTER 1
bit
default
7
1
6
0
5
0
4
0
3
0
2
0
1
0
0
0
PINS USED AS GENERAL PURPOSE I/Os
LED pins not used to control LEDs can be used as general purpose
I/Os.
For use as input: Set LEDx to high-impedance (00) and then read
the pin state via the input register.
For use as output: Connect external pull-up resistor to the pin and
size it according to the DC recommended operating characteristics.
LED output pin is HIGH when the output is programmed as
high-impedance, and LOW when the output is programmed LOW
through the “LED selector” register. The output can be pulse-width
controlled when PWM0 or PWM1 are used.
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 is: PWM1
256
LS0 — LED SELECTOR
LED3
bit
default
7
0
6
0
5
0
LED2
4
0
LED 1
3
0
2
0
LED 0
1
0
0
0
POWER-ON RESET
When power is applied to V
DD
, an internal Power-On Reset holds
the PCA9533 in a reset condition until V
DD
has reached V
POR
. At
this point, the reset condition is released and the PCA9533 registers
are initialized to their default states, with all outputs in the off state.
Thereafter, V
DD
must be lowered below 0.2 V to reset the device.
The LSx LED select registers determine the source of the LED data.
00 = Output is set Hi-Z (LED off – default)
01 = Output is set LOW (LED on)
10 = Output blinks at PWM0 rate
11 = Output blinks at PWM1 rate
2004 Oct 01
5
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