Zetex Semiconductors has offered ZXLD1350 switching regulator. Requiring a single external resistor to accurately set its output current, the ZXLD1350 dramatically simplifies high power LED driving. Operating from an input supply of between 7V and 30V, the driver can produce an adjustable output current of up to 350mA, to support an LED chain of up to eight 1 Watt LEDs.
The use of the 2.9mm x 2.8mm footprint TSOT23 5-pin package and high level of component integration means, the ZXLD1350 switching regulator will fit even the most space-starved application. By integrating a 30V NDMOS switch, and a high-side current sensing circuit yielding a +/-4% precision current control, the ZXLD1350 needs the support of a total of just four external circuit components.
Depending on the type and value of the external components used, the LED driver can achieve efficiency as high as 95%, which combined with low typical shutdown current of only 15µA, ensures the device offers good power economy and extended battery life.
With an operating temperature range from –40ºC to +105ºC, the ZXLD1350 can also tolerate temperatures more than 20% higher than alternative solutions. In addition, the ability to support a continuous supply voltage of 30V and surge voltages of 40V makes the ZXLD1350 suitable for even the most demanding industrial and automotive applications.
Where LED lighting applications require dimming and more complex control attributes, the ZXLD1350 also offers designers a wealth of alternative control strategies. The device’s multi-function control pin provides the ability to finely regulate the output current, by applying either a DC voltage or a PWM waveform – the PWM filter components are on-chip.
By adding a capacitor between the control pin and ground, the LED driver’s inherent soft-start time can be extended, and the application of a logic low signal to the pin enables the device output to be turned off.