Schukat has added a series of efficient LED drivers to its range. With its TS193, TS194, TS196 and TS197 series of constant-current LED drivers, Taiwan Semiconductor offers high-efficiency, buck/boost converter-based solutions for controlling white LEDs. The drivers deliver currents of up to 2A, with an efficiency of up to 91%.
In the 6-pole SOT223 package, the TS19371CX6 step-up converter/driver (boost) for white LEDs meets all the demands placed on a modern switching-regulator-based LED driver: Operation with low supply voltage (9-15V), fast switching frequency (1.2 MHz), high efficiency (up to 89%), extremely stable, adjustable LED operating current (up to 350mA), flexibility (various LED configurations can be operated) and dimmability (0% to 100%, 3 options).
With a supply voltage of 15V, for example, the TS19371 can regulate 126 LEDs in 14 parallel-switched strings of 9 LEDs, each with 20mA and efficiency of almost 89%, or a single LED string consisting of six white 1W HP LEDs with 350mA (efficiency 88%). The required LED operating current is established using a very small feedback resistor (e.g. 0.22Ω for 350mA) in the LED chain, ensuring that power dissipation from resistance is kept to a minimum. For operation, the TS19371 only requires four external components (two capacitors, a choke and a diode).
In the SO8 package, the TS19378CS is a buck converter with a switching frequency of 300kHz working on an input voltage range from 8-40V. The unit delivers up to 2A of driver current and on a 40V input, for example, can safely and efficiently power up to ten white high-power LEDs. The TS19452CS model is an LED driver ICthat can be operated on either 230V mains power with an upstream bridge rectifier and smoothing capacitor, or directly on high DC voltages up to 400V. Output is a constant 100mA, allowing the operation of long LED strings.