LTC3521 DC DC converter circuit

The LTC3521 integrated circuit designed by Linear Technology combines a 1A buck-boost DC DC converter and dual 600mA synchronous buck DC DC converters. The LTC3521 circuit use an 1.1MHz switching frequency that minimizes the solution foot­print while maintaining high efficiency. So the LTC3521 has all three converters in one package and offers features like : soft-start and internal compensation to minimize the solution footprint and simplify the design process.

The buck converters are current mode controlled and utilize an internal synchronous rectifier to improve ef­ficiency. The buck converters support 100% duty cycle operation to extend battery life. If the PWM pin is held low, the buck converters automatically transition from Burst Mode operation to PWM mode at high loads. With the PWM pin held high, the buck converters remain in low noise, 1.1MHz PWM mode.
At light loads, the buck-boost converter can be operated in Burst Mode operation to improve efficiency and reduce no-load standby current.
Main features of this DC DC converter are : three high efficiency DC/DC converters: buck-boost (VOUT: 1.8V to 5.25V, IOUT: 1A) ,dual buck (VOUT: 0.6V to VIN, IOUT: 600mA) , 1.8V to 5.5V input voltage range, pin-selectable burst mode operation , 30μA total quiescent current in burst mode operation ,integrated soft-start ,thermal and overcurrent protection.