NXP Semiconductors’ PCA9955TW/Q900 is a 16-channel LED driver which is ideal for use in automotive applications such as cabin lighting and indicator lighting.
When used in driver and passenger control panels, lower-power LEDs often require the implementation of safety-related features. For example, in safety-critical applications such as braking systems and engine health monitors, an indicator LED itself must be able to report open or short circuits that might cause faulty operation.
NXP’s PCA9955TW/Q900 meets this need because it features built-in open, short and over-temperature detection circuitry to provide for safe operation in automotive applications.
The error information from the corresponding register can be read via the I2C bus found in almost all automotive microcontrollers. Additionally, a thermal shut-down feature protects the device when its internal junction temperature exceeds its maximum limit.
The PCA9955TW/Q900 can switch up to 16 channels of LEDs and control their brightness using PWM signals. These channels can also be assigned to groups for global dimming, which is useful in vehicles when they are exposed to sunlight or moonlight.
The LED driver can also perform gradation: an automatic cycle that controls the ramp-up and ramp-down of an LED’s brightness. This is commonly used to indicate that a system is in Sleep mode, leaving an LED to ‘breathe’ by slowly turning on and off.
The registers in the PCA9955TW/Q900 are easily programmed so that the system designer can configure the rhythm of the LED’s blinking or breathing without imposing a burden on the MCU.
For backlighting with a string of LEDs, the PCA9955TW/Q900 provides a constant current, and an output voltage of up to 20V for long strings of LEDs.
Each channel can sink over 50mA with no additional components. The LEDs are connected directly the driver IC, which only requires a single global resistor for setting the maximum current.
- LED status information
- LED displays
- LCD backlights
- AEC-Q100 qualified
- 4% channel-to-channel matching
- 8-bit PWM control