Step-down LED driver with silent switcher topology minimises EMI concerns

Analog Devices, Inc., which recently acquired Linear Technology Corporation, announces the LT3932, a monolithic, synchronous, step-down DC/DC converter with internal 36V, 2A power switches and an internal PWM generator. Its fixed frequency, peak current mode control accurately regulates current within ±1.5% for strings of up to 2A LEDs. Its integrated PWM generator offers a 128:1 dimming ratio. If dimming ratios of up to 5000:1 are required, the LT3932 and an external PWM generator can accommodate these applications. The LT3932’s 3.6V to 36V input voltage range is ideal for a wide variety of applications, including automotive, industrial and architectural lighting. The combination of its Silent Switcher topology and spread spectrum frequency modulation minimizes EMI concerns. The LT3932 can drive up to eight 2A white LEDs from a nominal 32V input, delivering in excess of 50 watts.

The LT3932 can deliver efficiencies of 93% while switching at 2MHz, eliminating the need for external heat sinking and offering a tiny, compact solution footprint. Internal open/short LED protection and fault indication offers added reliability. The LT3932’s switching frequency is programmable from 200kHz to 2MHz or it can be synchronized to an external clock signal. Combined with a thermally enhanced 4mm x 5mm QFN package, the LT3932 offers a very compact high power LED driver solution. Other features include accurate LED current sense with a monitor output, 99.9% duty cycle operation and programmable UVLO.

The LT3932EUFD is available in a thermally enhanced 28-lead 4mm x 5mm QFN package. Three temperature grades are available, with operation from –40°C to 125°C (junction) for the extended, industrial grades and a high temperature grade of –40°C to 150°C. Pricing starts at $3.95 each in 1,000-piece quantities and all versions are available from stock.