QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 886 300mA VERY LOW DROPOUT LINEAR REGULATOR LTC3035 DESCRIPTION Demonstration circuit 886 is an ultra-low input voltage and dropout voltage supply using the LTC3035 linear regulator, which comes in a very small 8-pin DFN package. The DC886 has an input voltage range from 1.7V to 5.5V, an output voltage range between 0.4V and 3.6V, and is capable of delivering 300mA of output current. Due to the 0.4V reference of the LTC3035, the DC886 is capable of supplying power to very low voltage applications, such as a (relatively) high current voltage refer- ences. The DC886 comes assembled with small ceramic capacitors – 1uF – to demonstrate the LTC3035 maintaining stability with ceramic output capacitors. Design files for this circuit board are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. Table 1. Performance Summary (TA = 25°C) PARAMETER Minimum Input Voltage CONDITION VALUE 1.7V Maximum Input Voltage Output Voltage VOUT Typical Dropout Voltage Output Regulation 5.5V VIN = 1.7V to 5.5V, IOUT = 0A to 300mA 1.8V ±3% VIN = 1.7V, IOUT = 300mA 45mV Line ±0.5% Load ±0.5% QUICK START PROCEDURE The DC886 demonstration board is easy to set up to evaluate the performance of the LTC3035. For proper measurement equipment configuration, set up the circuit according to the diagram in Figure 1. Before proceeding to test, insert jumper JP5 shunt into the off (lower) position, connecting the RUN pin to ground (GND), which shuts down the circuit. NOTE: When measuring the input or output ripple or noise voltage, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the voltages by touching the probe tip directly across the VIN or VOUT and GND terminals. See Figure 2 for proper scope probe technique. 1. Connect the input power supply and the load to the board. Do not hot-plug VIN or increase VIN over the rated maximum supply voltage of 5.5V, or the part may be damaged. Refer to Figure 1 for the proper measurement equipment setup. 2. Select any of the output voltages by inserting a shunt into that output voltage jumper position. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 886 300mA VERY LOW DROPOUT LINEAR REGULATOR 3. Apply 5V at VIN. Measure VOUT; it should read 0V. If desired, one can measure the shutdown supply current at this point. The supply current will be approximately 1uA in shutdown. 4. Turn on the circuit by inserting the shunt on jumper JP5 into the ON (upper) position. The output voltage should be regulating to +/-2% of its selected value (see the table below). No Load 5. Vary the input voltage from VOUT plus the dropout voltage (45mV typically at 300mA of output current) to 5.5V and adjust the load current from 0 to 300mA. VOUT should read +/-3% of its selected value (see the table below). When finished, turn off the circuit by inserting the shunt on jumper JP5 into the OFF (lower) position. Max Load or Max Load and Line Variation Line Variation 2% 2.5% 3% VOUT = 1.8V 1.764V – 1.836V 1.755V – 1.845V 1.746V – 1.854V VOUT = 2.5V 2.45V – 2.55V 2.437V – 2.563V 2.425V – 2.575V VOUT = 3.3V 3.234V – 3.366V 3.217V – 3.383V 3.201V – 3.399V 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 886 300mA VERY LOW DROPOUT LINEAR REGULATOR Figure 1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 886 300mA VERY LOW DROPOUT LINEAR REGULATOR 4