DEMO CIRCUIT 932A QUICK START LT3689 GUIDE LT3022 1A, Low Voltage, Very Low Dropout Linear Regulator DESCRIPTION Demonstration circuit 932A is an adjustable 1A linear regulator featuring LT3022. The LT3022 is a very low dropout voltage (VLDOTM) linear regulator that operates from input supplies down to 0.9V. The device supplies 1A output current with 145mV typical dropout voltage. The LT3022 is ideal for low input voltage to low output voltage applications, providing comparable electrical efficiency to a switching regulator. The regulator optimizes stability and transient response with low ESR ceramic output capacitors as small as 10μF. Other LT3022 features include 0.05% typical line regulation and 0.05% typical load regulation. In shutdown, the quiescent current typically drops to 7.5μA. Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting with hysteresis and reverse-current protection. Minimum input voltage is the voltage required by the LT3022 to regulate the output voltage and supply the rated 1A output current. This specification is tested at VOUT = 0.2V. For higher output voltages, the minimum input voltage required for regulation equals the regulated output voltage VOUT plus the dropout voltage or 1.1V, whichever is greater. The LT3022 is available as an adjustable device with an output voltage range down to the 200mV reference. The LT3022 regulator is available in the thermally enhanced low profile (0.75mm) 16-lead (5mm × 3mm) DFN and MSOP packages. The LT3022 datasheet gives a complete description of the part, operation and application information. The datasheet must be read in conjunction with this quick start guide for demo circuit 932A. Design files for this circuit board are available. Call the LTC factory. L, LTC and LT are registered trademarks of Linear Technology Corporation. VLDO is a trade mark of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products. Performance Summary ( TA = 25oC ) PARAMETER Minimum Input Voltage Maximum Input Voltage Output Voltage VOUT CONDITIONS VOUT = 1.2V, IOUT = 1A Shunt at 1, 2 for JP2 Shunt at 3, 4 for JP2 Shunt at 5, 6 for JP2 Shunt at 7, 8 for JP2 Shunt at 9, 10 for JP2 Shunt at 11, 12 for JP2 VALUE 1.35V 10V 0.9V ± 3% 1.0V ± 3% 1.2V ± 3% 1.5V ± 3% 1.8V ± 3% User Select 1 LT3022 QUICK START PROCEDURE Demonstration circuit 932A is easy to set up to evaluate the performance of the LT3022. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 4. Turn on the power at the input. NOTE. Make sure that the input voltage does not exceed 10V. 5. Check for the proper output voltages. NOTE. If there is no output, temporarily disconnect the load to make sure that the load is not set too high or is shorted. NOTE. When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the terminals of the input or output capacitors. See Figure 2 for proper scope probe technique. 6. Once the proper output voltage is established, adjust the loads within the operating range and observe the output voltage regulation, efficiency and other parameters. 1. Place JP1 on the ON position. 2. Use JP2 to set the desired output voltage. 3. With power off, connect the input power supply to VIN and GND. NOTE. Make sure that the power dissipation is limited below the thermal limit. Figure 1. Measurement Equipment Setup GND VIN Figure 2. Measuring Input or Output Ripple 2 LT3022 3