Diodes, a producer and supplier of superior-quality, application-specific devices in the semiconductor market sector has introduced the AL5802 linear LED driver for providing cost effective solutions for current control.
300V LED Driver
The LED Driver is designed by integrating a high gain NPN transistor with a pre-biased NPN output transistor having a rating of 30 V. The device is an ideal solution for low EMI current controlling circuits that control up to nine low power series connected LEDs. The driver provides an open-collector output, which can operate between 0.8 and 30 V. The driver is packaged as an SOT26 and is compatible with power supplies from 12 to 24 V. The output current delivered by the LED ranges from 20 mA to 100 mA. This output range can be used in LED signs, automotive interior display applications and in lighting lamps as well.
To set the LED current, a low-value resistor is needed externally, which is the only extra component that the driver requires. The reference voltage for the resistor is 0.65V, a transistor with a high value of internal gain helps in reducing the power loss and provides necessary headroom for the supply voltage. The protection mechanism for the LEDs is taken care by the negative temperature coefficient of the reference voltage, which reduces the LED current automatically at high temperatures. The PWM dimming of the LED series can be achieved easily by lowering the impedance of the device bias pin or by driving its enable pin with the help of an open collector NPN transistor or a open drain N-channel MOSFET. The LED driver comes with a wide operating temperature range and hence is safe to be mounted close to the LEDs in situations where space is a constraint.