DEMO MANUAL DC2240A LT8714 Synchronous Four-Quadrant Converter Description Demonstration circuit 2240A is a synchronous four- jumper to select the CTRL pin voltage source from either quadrant converter featuring the LT 8714 switching externally (EXT) or internally (INT). If selected internally, controller. The LT8714 can regulate to positive, negative, the output voltage can be set to +5V or 5V. If selected or zero volts when configured as a four-quadrant topol- externally, the output voltage can vary between positive ogy. The DC2240A regulates from a 10V to 14V input 5V and negative 5V, following a 0.1V 1V CTRL signal source to an adjustable output voltage from positive 5V with high bandwidth. to negative 5V with a 5A maximum current rating, and The LT8714 data sheet gives a complete description of operates at 200kHz switching frequency. the part, operation and application information. The data The LT8714 incorporates a power good feature to let sheet must be read in conjunction with this quick start the user know if the output voltage is within its target guide for demo circuit 2240A. regulation voltage. Design files for this circuit board are available at The LT8714 has an output voltage control (CTRL) pin DEMO MANUAL DC2240A Quick s p D Demonstration circuit 2240A is easy to set up to evalu- 3. Check for the proper output voltages. The output should ate the performance of the LT8714. Refer to Figure 1 for be regulated at +5.0V (3%). proper measurement equipment setup and follow the If there is no output, temporarily disconnect the load procedure below: to make sure that the load is not set too high. 1. With the power off, connect the input power supply to 4. Once the proper output voltage is established, adjust the board through V and PGND terminals. Connect IN the input voltage and load current within the operating the load to the terminals V and PGND on the board. OUT range and observe the output voltage regulation, ripple Make sure that the input power supply has sufficient voltage, efficiency and other parameters. current rating at minimum input voltage for the required NOTE: When measuring the input or output voltage output load. ripples, care must be taken to avoid a long ground lead 2. Turn on the power at the input. on the oscilloscope probe. Measure the input or output NOTE: Make sure that the input voltage does not voltage ripple by touching the probe tip directly across exceed 14V. the V and PGND, or V and PGND terminals. See IN OUT Figure 2 for proper scope probe technique. I I IN OUT + + + + + POWER V V IN OUT SUPPLY DC2240A F01 Figure1. Proper Measurement Equipment Setup dc2240af 2 ure roce tart