36V, 2A synchronous step-down automotive LED driver minimizes EMI

36V, 2A synchronous step-down automotive LED driver minimizes EMI

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LT3932 is a monolithic, synchronous, step-down DC/DC converter with internal 36V, 2A power switches and an internal PWM generator, employing Linear’s Silent Switcher architecture. Its fixed frequency, peak current mode control accurately regulates current within ±1.5% for strings of up to 2A LEDs.
By Graham Prophet

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The part’s 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 suits 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 50W.

 

The LT3932 can deliver efficiencies of 93% while switching at 2 MHz, 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 200 kHz to 2 MHz or it can be synchronized to an external clock signal. Combined with a thermally enhanced 4 x 5 mm 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.

 

In a thermally enhanced 28-lead 4 x 5 mm QFN package, pricing starts at $3.95 (1000).

 

Analog Devices/Linear Technology; www.linear.com/product/LT3932

 

next page; feature summary….


Summary of Features: 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

Silent Switcher® Architecture for Low EMI

3.6V to 36V Input Voltage Range

0V to 36V LED String Voltage

2A, 36V Internal Switches

200kHz to 2MHz with SYNC Function

99.9% Maximum Duty Cycle

Analog or Duty Cycle LED Current Control

Open/Short LED Protection & Fault Indication

Accurate LED Current Sense with Monitor Output

Programmable UVLO

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

 

 

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