Demonstration circuit 2727A is a high input voltage, high efficiency dual output DC/DC converter. It features the LTC®3892‑2, a low IQ, dual output, 2-phase synchronous step-down DC/DC controller. This demo board operates over a 6V to 40V input voltage range and produces a 3.3V at 10A and a 12V at 3A output.
The 12V output is designed using a SEPIC converter which allows a stable output voltage from an input voltage that can be above, below or equal to the output voltage. The 3.3V is provided using a synchronous step-down converter. These output voltages can easily be changed with certain modifications.
The gate drive voltage can be adjusted from 5V to 10V allowing the use of logic or standard level MOSFETs. The DC2727A supports three operation modes: forced continuous mode, pulse-skipping and Burst Mode® operation during light loads. Forced continuous mode reduces output voltage ripple and yields a low noise switching spectrum. The pulse-skipping and burst modes increased efficiency at light loads.
Both outputs of the DC2727A switch out of phase to reduce input filtering. The DC2727A supports selectable current limit and provides very low dropout operation with its 99% duty cycle capability. The DC2727A has a standard operating frequency of 250kHz, but can be adjusted in a range between 75kHz and as high as 850kHz. In addition, the LTC3892-2 integrates the bootstrap diodes which simplifies the design.
The DC2727A was designed to support multiple footprints of input/output capacitors and inductors to accommodate variety of applications. The data sheet of LTC3892-2 gives a complete description and application information, and must be read in conjunction with this demo board manual for DC2727A.