MILPITAS, CA - December 3, 2009 - Linear Technology Corporation announces the LT3686, a 1.2A, 37V_IN step-down switching regulator. The LT3686 operates within a V_IN range of 3.6V to 37V with overvoltage lockout, protecting the regulator and load from transients as high as 55V, making it ideal for load dump and cold-crank conditions commonly found in automotive applications as well as 24V industrial supplies. Its internal 1.85A switch can deliver up to 1.2A of continuous output current at voltages as low as 0.8V. Its low minimum on-time enables it to offer high switching frequencies even with high step-down ratios. For example, with an input as high as 16V, it can deliver a 3.3V output using a 2MHz switching frequency. The LT3686's switching frequency is user programmable from 300kHz to 2.5MHz, enabling designers to maximize efficiency while avoiding critical noise-sensitive frequency bands. The LT3686 also uses a unique design, which ensures that it maintains constant frequency switching, even in very light load conditions. The device's 3mm x 3mm DFN-10 package and high switching frequency, which keeps the external inductor and capacitors small, provides a compact, thermally efficient footprint.

The LT3686 utilizes a high efficiency 1.85A, 680mV switch with the necessary boost diode, oscillator, control and logic circuitry integrated into a single chip. Its catch diode current sense (DA pin) protects the circuit during input voltage transients even at high switching frequencies. Special design techniques used in the LT3686 enable high efficiency over a wide input voltage range, and the device's current mode topology enables fast transient response and excellent loop stability. Other features include tracking capability, internal compensation and soft-start capability.

Pricing for the LT3686EDD starts at $2.50 each for 1,000-piece quantities. An industrial grade version, LT3686IDD, is guaranteed to operate from a -40ºC to 125ºC operating junction temperature and is priced at $2.78 each. Both versions are available from stock. For more information, visit www.linear.com.

Summary of Features: LT3686 Wide Input Range:   • Operation from 3.6V to 37V   • Overvoltage Lockout Protects Circuit through      55V Transients Low Minimum On-Time: Converts 16VIN to 3.3VOUT at 2MHz 1.2A Output Current Adjustable Frequency: 300kHz to 2.5MHz, with ±5% Accuracy Constant Switching Frequency at Light Loads Tracking & Soft Start Precision UVLO Short-Circuit Robust IQ in Shutdown <1µA Internally Compensated 3mm × 3mm DFN Package

37VIN, 1.2A(IOUT), 2.5MHz Step-Down DC/DC Converter Click Photo for High-Res Image