DC-DC Controller Generates Positive Or Negative Voltages

'Offering a wide input range of 2.9 to 40 V, the LT3757 dc-dc controller can generate either positive or negative regulated output voltages. The device incorporates two voltage feedback error amplifiers and reference voltages, one set for positive output voltages, with a 1.6-V reference, and one set for negative output voltages, with a ?0.80-V reference, both off a single feedback pin. This makes the device a very versatile controller for use in many types of power supplies, including boost, flyback, SEPIC, and inverting supplies. The LT3757 achieves efficiencies of up to 96% and uses a programmable fixed or synchronizable operating frequency from 100 kHz to 1 MHz, allowing designers to choose a wide range of inductors and capacitors to optimize size, performance, and cost. The controller drives an external N-channel MOSFET from an internally regulated 7.2-V supply. Programmable soft start allows for control of the output voltage turn-on time. The LT3757 comes in a thermally enhanced MSOP-10 or 3- by 3-mm DFN-10 package, both with extended and industrial temperature ranges from ?40°C to 125°C. Pricing starts $2.06 each in quantities of 1000. LINEAR TECHNOLOGY CORP., Milpitas, CA. (408) 398-9700.