DEMO MANUAL DC1585A LT3083 Adjustable 3A Single Resistor Low Dropout Regulator DESCRIPTION Demonstration circuit 1585A is an adjustable 3A linear Internal protection circuitry includes current limiting and regulator featuring LT3083. Architected as a precision thermal limiting. current source and voltage follower, it allows this new LT3083 regulator is offered in a 16-lead TSSOP (with an regulator to be used in many applications requiring high exposed pad for better thermal characteristics), a 4mm current, adjustability to zero output, and no heat sink. Also 4mm DFN, 5-lead TO-220 and a 5-lead DD-PAK version. the device brings out the collector of the pass transistor The LT3083 datasheet gives a complete description of the to allow low dropout operation when used with multiple part, operation and application information. The datasheet supplies. should be read in conjunction with this quick start guide A key feature of the LT3083 is the capability to supply a for working on or modifying the demo circuit 1585A. wide output voltage range. DC1585A can be set to 1.2V, Design files for this circuit board are available at 1.5V, 1.8V, 2.5V, 3.3V, 5.0V, as well as user selectable. DEMO MANUAL DC1585A QUICK START PROCEDURE 5. Turn on the power at V . IN Demonstration circuit 1585A is easy to set up to evalu- NOTE. Make sure that the V voltage does not exceed IN ate the performance of the LT3083. Refer to Figure 1 for 23V. the proper measurement equipment setup and follow the 6. Check for the proper output voltages. procedure below: NOTE. If there is no output, temporarily disconnect NOTE. When measuring the input or output voltage the load to make sure that the load is not set too high ripple, care must be taken to avoid a long ground lead or is shorted. on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across 7. Once the proper output voltages are established, adjust the terminals of the input or output capacitors. See the loads within the operating range and observe the Figure 2 for the proper scope probe technique. output voltage regulation, efficiency and other param- eters. 1. Use JP1 to set the desired output voltage. NOTE. Make sure that the power dissipation is limited 2. With power off, connect the bias power supply to below the thermal limit. V and GND. CONTROL 3. With power off, connect the input power supply to V IN and GND. 4. Turn on the power at V . CONTROL NOTE. Make sure that the V voltage does not CONTROL exceed 25V. + LOAD + + POWER SUPPLY + + + + POWER SUPPLY + + Figure 1. DC1585A Proper Equipment Setup dc1585af 2