60V synchronous 4-switch buck-boost controller with spread spectrum

November 24, 2016 // By Graham Prophet
LT8390 is a synchronous buck-boost DC/DC controller that can regulate output voltage, and input or output current from input voltages above, below and equal to the output voltage. Its 4V to 60V input voltage range and 0V to 60V output voltage range are aimed at voltage regulator, battery and supercap charger applications in automotive, industrial, telecom and battery-powered systems.

The chip’s 4-switch buck-boost controller, combined with 4 external N-channel MOSFETs, can deliver from 10W to over 400W of power with efficiencies up to 98%. Its buck-boost capability is suitable for applications such as automotive, where the input voltage can vary dramatically during stop/start, cold crank and load dump conditions. Transitions between buck, buck-boost and boost operating modes are seamless, offering a well regulated output even with wide variations of supply voltage. The LT8390 is offered in either a 28-lead 4 x 5 mm QFN or thermally enhanced TSSOP to provide a very compact solution footprint.


The LT8390 uses a proprietary peak-buck, peak-boost current mode control scheme which uses a single inductor current sense resistor to provide a seamless transition between buck, boost and buck-boost regions. Output voltage is delivered with ±1.5% accuracy, whereas output current accuracy of ±3% ensures accurate constant current regulation. The LT8390 can be programmed to use a fixed switching frequency between 150 kHz to 650 kHz with synchronization, or it can use internal spread spectrum operation for lower EMI. Additional features include an input or output current monitor, power good flag, integrated bootstrap diodes and short-circuit protection with fault reporting. Pricing starts at $4.65 (1,000).


Linear Technology; www.linear.com/product/LT8390


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