Minimize EMI problems with the LT3932 monolithic, synchronous, step-down DC/DC converter

Linear Technology Corporation of Milpitas, Calif., and NORWOOD, MA, a single-chip, LT3932, a synchronous, step-down DC/DC converter with an internal 36V, 2A power switch and an internal PWM generator. Its fixed frequency, peak current mode control accurately regulates currents to within ±1.5% for LED strings up to 2A. Its integrated PWM generator provides a 128:1 dimming ratio. If a dimming ratio of up to 5000:1 is required, the LT3932 and an external PWM generator are suitable for this type of application. The LT3932's 3.6V to 36V input voltage range is ideal for a wide range of applications, including automotive, industrial and architectural lighting. Its Silent Switcher® topology and spread spectrum frequency modulation combine to minimize EMI issues. The LT3932 drives up to eight 2A white LEDs with a nominal 32V input, providing over 50W.

The LT3932 delivers 93% efficiency while switching at 2MHz, eliminating the need for external heat dissipation and providing a compact and compact footprint solution. Internal open/short LED protection and fault indication provide enhanced reliability. The LT3932's switching frequency is programmable from 200kHz to 2MHz or can be synchronized to an external clock signal. Combined with a thermally enhanced 4mm x 5mm QFN package, the LT3932 forms a very compact, high power LED driver solution. Other features include accurate LED current sensing with 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. Available in three temperature grade versions, extended and industrial temperature grade versions operating from –40°C to 125°C (junction temperature) and high temperature versions operating from –40°C to 150°C . The 1,000-piece purchase price is $3.95 per piece and all versions are available from stock. For more information, please log in

LT3932.

Performance Summary: LT3932                              

?    ±1.5% LED current regulation

?    ±1.2% output voltage regulation

?    5000:1 PWM dimming at 100Hz

?    128:1 internal PWM dimming

?    Spread spectrum frequency modulation

?    SilentSwitcher® architecture for low EMI

?    3.6V to 36V input voltage range

?    0V to 36V LED string voltage

?    2A, 36V internal switch

?    200kHz to 2MHz switching frequency and SYNC function

?    99.9% maximum duty cycle

?    Analog or Duty Cycle LED Current Control

?    Open/short LED protection and fault indication

?    Accurate LED current sensing with monitor output

?    Programmable UVLO

?    Thermally Enhanced 28-Lead (4mm × 5mm) QFN Package

 

The quotes given in this article are for budgetary purposes only. Quotations around the country may vary depending on local tariffs, taxes, fees and exchange rates.