Driver eases low power led control says Diodes
1 min read
Diodes has announced a new linear led driver which integrates a high gain NPN transistor with a 30V rated pre biased NPN output transistor.
The AL5802 device is designed to provide a cost effective and low emi solution for controlling current in up to nine low power series connected leds.
The SOT26 packaged driver features an open collector output which Diodes says is capable of operating between 0.8 to 30V and will support 12 and 24V power supplies. It is designed to deliver led currents between 20 to 100mA for led signs, lamps and automotive interior display applications.
The led current is set via an external low value resistor, the one additional component required by the driver. By generating a reference voltage of 0.65V across the resistor, the internal high gain transistor is said to help minimise power losses and ensure supply voltage headroom. According to Diodes, the negative temperature coefficient of the reference voltage means that led current is automatically reduced at high temperatures, helping to protect leds and improve circuit reliability.
PWM dimming of the led string is also achievable by either driving the device bias pin with a low impedance voltage source or driving its enable pin with an external open collector NPN transistor or open drain N-Channel mosfet.
The AL5802's ambient temperature operating range of -40 to 125ºC enables it to be circuit mounted close to the leds in space limited lighting applications.
