DC/DC controller eliminates ripple, reduces EMI

October 23, 2015 // By Christoph Hammerschmidt
The LTC7812 from power regulation specialist Linear Technology is a dual output synchronous DC/DC controller. In contrast to other single inductor buck-boost regulators, the LTC7812 follows a cascaded boost-and-buck approach for fast transient response with continuous, non-pulsating, currents, substantially reducing ripple voltage and electromagnetic interference (EMI). This feature makes the LTC7812 ideal for automotive, industrial and high power battery operated systems.

The device operates from an input voltage of 4.5V to 38V and maintains operation down to 2.5V after start-up. It can produce output voltages up to 60V and can run at 0% duty cycle (synchronous switch ON) to pass through the input voltage when required for maximum efficiency. The step-down converter can produce output voltages from 0.8V to 24V with an efficiency as high as 98%.


In addition, the LTC7812 can be configured for Burst Mode operation, reducing quiescent current to 28µA with the buck channel on (33µA for both channels on) in sleep mode, a useful feature for preserving battery run time. The 1Ω onboard all N-channel gate drivers minimize MOSFET switching losses and provide an output current of more than 10 amps per channel, limited only by external components. The output current for each converter is sensed by monitoring the voltage drop across the inductor (DCR) or by using a separate sense resistor.

The LTC7812’s constant frequency current mode architecture enables a selectable frequency from 50kHz to 900kHz or it can be synchronized to an external clock from 75kHz to 850kHz. Additional features include adjustable soft-start or tracking, foldback current limit, output overvoltage protection, run control and a power good output voltage signal. The LTC7812 is available in a 32-lead 5mm x 5mm QFN package. The 1,000-piece price starts at $4.00 each.


For more information, visit www.linear.com/product/LTC7812.