QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 704 DUAL OUTPUT LOW NOISE LDO REGULATORS LT3023 DESCRIPTION Demonstration circuit 704 is a dual output regulator tors, because of the LT3023 ability of maintaining based on the LT3023 IC, which consists of two iden- stability with ceramic output capacitors. There are tical LDO linear regulators. The DC704 has an input ceramic bypass capacitors on each output for extra voltage range of 2.3V to 20V, and either output is ca- low noise performance. These features make the pable of delivering up to 100mA of output current. DC704 an ideal circuit for use in battery-powered, The DC supply current is typically only 20uA (per hand-held applications or noise sensitive applica- channel) at no load. The LT3023 comes in a small tions. 10-pin DFN package, which has an exposed pad on Design files for this circuit are available. Call the the bottom-side of the IC for better thermal perform- LTC Factory. ance. DC704 comes installed with ceramic capaci- QUICK START PROCEDURE DC704 is easy to set up to evaluate the performance 6. Vary each load current from 0 to 100mA. of the LT3023. Refer to Figure 1 for proper meas- Both output voltages should be within a toler- urement equipment setup and follow the procedure ance of +/- 4%. outlined below for proper operation. 7. Observe both output voltages AC-coupled they should measure noise voltages of less than 2mVAC each. Refer to Figure 2 for 1. Connect the input power supply to the VIN proper measurement technique. and GND terminals. Connect the loads be- tween the VOUT and GND terminals. 8. When finished, move jumpers JP3 and JP4 to the OFF position and disconnect the power. 2. Before proceeding to operation, insert jump- ers JP3 and JP4 into the OFF positions, jump- ers JP1 and JP2 into the voltage options of Warning - if long leads are used to power the demo choice (2.5V, 3.3V, and 5V). circuit, the input voltage at the part could ring, 3. Apply 6.5V at VIN. Measure both VOUT1 and which could affect the operation of the circuit or even VOUT2 they should read 0V. exceed the maximum voltage rating of the IC. To eliminate the ringing, insert a small tantalum capaci- 4. Turn on VOUT1 and VOUT2 by moving jump- tor (for instance, an AVX part TAJW106M025R) on ers JP3 and JP4 from the OFF position to the the pads between the input power and return termi- ON position. Both output voltages should be nals on the bottom of the demo board. The (greater) within a tolerance of +/- 2%. ESR of the tantalum will dampen the (possible) ring- 5. Vary the input voltage from 6.5V to 20V. Both ing voltage due to the use of long input leads. On a output voltages should be within +/- 3.3% tol- normal, typical PCB, with short traces, the capacitor erance. is not needed. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 704 DUAL OUTPUT LOW NOISE LDO REGULATORS Figure1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple 2