Eindhoven, The Netherlands - Royal Philips Electronics is announcing two new General Purpose I/O expanders (PCA953x and PCA955x) optimized for controlling LED dimming and blinking. The I^2C are targeting applications ranging from mobile phones to servers in computing, communication, and networking applications.
These new 2-, 4-, 8-, and 16-bit devices allow designers an easy way to build systems with more dimming or blinking LEDs than previously possible using just basic General Purpose I/Os (GPIO) or microcontrollers (MCUs).
Manufacturers of applications such as cell phones and servers are increasingly requiring multiple blinking LEDs for eye-catching keypad lighting applications, as well as practical purposes such as status indication. The new PCA953x LED Dimmers and PCA955x LED Blinkers allow more system flexibility by off-loading the LED power consumption and by eliminating the programming of the MCU.
The new I^2C devices have an internal oscillator with four 8-bit (256 values) internal registers that are used to set two programmable blink rates. This removes the need for the MCU to use one of its timers to send repeated commands to "blink" LEDs (repeatedly turning individual LEDs on and off). It also significantly reduces the I2C bus traffic compared to when a standard GPIO is used to blink or dim the LED freeing up the I2C bus for additional traffic and control of additional devices.
Once programmed, the internal oscillator allows the I2C bus to be disconnected from the PCA953x or PCA955x with the LED continuing to be dimmed or blink, something not possible with normal GPIOs. This enables electronics manufacturers to more simply blink and/or dim LEDs in their systems, while freeing up the microcontroller and the I2C bus for more efficient operation of the system.
The PCA953x LED Dimmers have a frequency range of 160Hz to once every 1.6 seconds, with a duty cycle range of completely off to 99.4 percent on allowing both dimming and blinking of LEDs. The PCA955x LED Blinkers have a frequency range of 40Hz to once every 6.4 seconds with a duty cycle range of 0.6 percent off to completely on, that allows designers to set, for example, a 4 second blink rate with the LED on for 1 second and then off for 3 seconds.
Output drive strength is 25mA per bit at 5V operation and 100mA for 8 bit groups, which is much more than the amount of current typically allowed by an MCU. The devices operate between 2.3V and 5.5V and up to a 400kHz I2C bus speed. Any I/O pins not used as outputs can be configured and used as normal general-purpose inputs.
Pricing and Availability
The device prices in quantities of 10,000 for the SO and TSSOP packages are: $0.75 for the PCA9530/50; $0.95 for the PCA9531/51; $1.20 for the PCA9532/52; and $0.75 for the PCA9533/53. The space-saving 4mm x 4mm HVQFN package option for the PCA9531/51 and PCA9532/52 has a 5% cost adder.
The 8-pin PCA9550 2-bit LED Blinker, 16-pin PCA9551 8-bit LED Blinker, 24-pin PCA9552 16-bit LED Blinker/PCA9532 16-bit LED Dimmer, and 8-pin PCA9553 4-bit LED Blinker are available now. The 8-pin PCA9530 2-bit LED Dimmer, 16-pin PCA9531 8-bit LED Dimmer, and 8-pin PCA9533 4-bit LED Dimmer are sampling now with releases through the end of the year.