Whenever a lighting application, such as street lighting for example, requires an elevated number of LEDs, there are basically two solutions: the first is to connect all the diodes in series in a single "string"; the second is to place several strings in parallel with fewer elements in each one.
The Texas Instruments TPS61150EVM-150 evaluation module contains the TPS61150 IC. This EVM provides two independently regulated current outputs using a single inductor step-up (boost) converter.
This evaluation board is designed around an L6902D-based DC-DC converter with dimming interface. The board implements both of two well known dimming methods: - Analog current control - Average current control by PWM
The ZXSC400, although designed for small LEDs in LCD backlighting, is sufficiently flexible to provide an efficient 1W solution producing a nominal 350mA constant current source from 2 NiMH or NiCd cells.
This design note shows a typical ZXSC310 LED driver circuit for a solar power garden light. The input voltage ranges from 1.7V to 2.5V with a maximum output current of 160mA at 2.4V input.
The ZXLD1350 is a continuous mode inductive step-down converter, designed for driving single or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 7V and 30V and provides an externally adjustable output current of up to 350mA.
This wide range evaluation board showcases the LM3424 NFET controller used with a buck-boost current regulator. It is designed to drive 4 to 10 LEDs at a maximum average LED current of 1A from a DC input voltage of 10 to 70V.
The LM3404HV circuit and BOM have been designed to provide a constant forward current of 1.0A to a single LED with a forward voltage of approximately 3.7V from an input of 48V ±10%. Over the input voltage range of 6V to 75V the average LED current, IF, is 1.0A ±10%, the ripple current, ΔiF, will not exceed 400 mAP-P, and the switching frequency is 200 kHz ± 10%.
The ZXSC400 is voltage mode boost converter in SOT23-6 package. Its low feedback voltage allows the current in a chain of LEDs to be set and accurately monitored with a single resistor with minimal losses. The ZXSC400EV4 is configured as a boost converter to drive a 1W LED from two NiCd / NiMH batteries.
This evaluation board showcases the LM3409HV PFET controller for a buck current regulator. It is designed to drive 12 LEDs (VO = 42V) at a maximum average LED current (ILED = 1.5A) from a DC input voltage (VIN = 48V). The switching frequency (fSW = 400 kHz) is targeted for the nominal operating point, however fSW varies across the entire operating range.