DEMO MANUAL DC2727A LTC3892-2EUH Dual Output SEPIC and Buck Converter DESCRIPTION Demonstration circuit 2727A is a high input voltage, high Both outputs of the DC2727A switch out of phase to efficiency dual output DC/DC converter. It features the reduce input filtering. The DC2727A supports selectable LTC 38922, a low I , dual output, 2 phase synchronous current limit and provides very low dropout operation with Q step down DC/DC controller. This demo board operates its 99% duty cycle capability. The DC2727A has a stan over a 6V to 40V input voltage range and produces a 3.3V dard operating frequency of 250kHz, but can be adjusted at 10A and a 12V at 3A output. in a range between 75kHz and as high as 850kHz. In addi tion, the LTC3892 2 integrates the bootstrap diodes which The 12V output is designed using a SEPIC converter simplifies the design. which allows a stable output voltage from an input volt age that can be above, below or equal to the output volt The DC2727A was designed to support multiple footprints age. The 3.3V is provided using a synchronous step down of input/output capacitors and inductors to accommodate converter. These output voltages can easily be changed variety of applications. The data sheet of LTC3892 2 gives with certain modifications. a complete description and application information, and must be read in conjunction with this demo board manual The gate drive voltage can be adjusted from 5V to 10V forDC2727A. allowing the use of logic or standard level MOSFETs. The DC2727A supports three operation modes: forced con Design files for this circuit board are available at tinuous mode, pulse skipping and Burst Mode opera DEMO MANUAL DC2727A QUICK START PROCEDURE Demonstration circuit 2727A is easy to set up to evaluate 2. Turn on V of the circuit by inserting the shunt OUT1 the performance of the LTC3892 2. For proper measure in header JP1 (RUN1) into the ON position. Voltage ment equipment configuration, set up the circuit accord should be regulating. Measure V , it should mea OUT1 ing to the diagram in Figure 1. Before proceeding to test, sure 3.3V 2% (do not apply more than the rated insert shunts into JP1, JP2 (RUN1, 2) into OFF position, maximum voltage of 40V to the board or the part may which connects the RUN pins to ground (GND), and thus be damaged). Vary the V load, which should not OUT1 shuts down the outputs. exceed 10A. Vary the input voltage from 6V to 40V. V should measure 3.3V 2%. OUT1 NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead 3. Turn on V of the circuit by inserting the shunt in OUT2 on the oscilloscope probe. Measure the input or output header JP2 (RUN2) into the ON position. The output voltage ripple by touching the probe tip directly across voltage should be regulating. Measure V , it should OUT2 the V or V and GND terminals. See Figure 2 for measure 12V 2% (do not apply more than the rated IN OUT proper scope probe technique. maximum voltage of 40V to the board or the part may be damaged). Vary the V load, which should not OUT2 1. With the DC2727A set up according to the proper mea exceed 3A. Vary the input voltage from 6V to 40V. surement and equipment in Figure 1, apply 14V at V . IN V should measure 12V 2%. OUT2 Measure V and V , both should read 0V. OUT1 OUT2 Figure 1. Proper Measurement Equipment Setup UG-1321 Rev 0 2