MOTION CONTROL: Linear Technology Corp.’s LTC3788/-1 is a dual output, high power synchronous step-up switching dc/dc controller that replaces the boost diode with a high efficiency N-Channel MOSFET. This eliminates the heat sink normally required in medium to high power boost converters. The LTC3788/-1 can produce a 24V at 5A output with up to 97 percent efficiency, making it ideal for high power automotive audio amplifiers, industrial and medical applications where a step-up dc/dc converter must deliver high power with low heat dissipation in a small solution size.
The LTC3788/-1 operates from an input voltage ranging from 4.5 to 38V during start-up, maintains operation down to 2.5V after start-up and can regulate an output voltage as high as 60V. The powerful 1.5Ohm onboard N-channel MOSFET gate drivers are capable of slewing large MOSFET gates quickly, minimizing transition losses and allowing for up to a 10A per channel output current. In addition, the LTC3788/-1 draws only 125 µA when one output is active and only 200 µA when both outputs are enabled.
The constant frequency current mode architecture allows for paralleled outputs. The LTC3788 includes a clock output, phase modulation (for multiphase applications), two separate power good outputs and an adjustable current limit. The LTC3788/-1 has a phase-lockable frequency from 75 to 850 kHz or a selectable fixed frequency from 50 to 900 kHz. It has adjustable cycle-by-cycle current limit protection and uses either a sense resistor or monitors the voltage drop across the inductor (DCR) for current sensing. In applications where the input voltage may sometimes exceed the regulated output voltage, the LTC3788/-1 is able to keep the synchronous MOSFET on continuously so that the output voltage follows the input voltage with minimal power loss. Furthermore, the LTC3788/-1 has adjustable soft-start and maintains ±1 percent reference voltage accuracy over an operating temperature range of -40 to 125C.
The LTC3788-1 is available in an SSOP-28 package and the LTC3788 is housed in a 32-lead 5 x 5 mm QFN. The 1,000-piece price starts at $4.12 each. Both versions are available from stock.
- Edited by Liz Taurasi