QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 534 LOW VOLTAGE LDO LINEAR REGULATOR LT3150 DESCRIPTION Demonstration circuit 534 is a fast transient response, dropout voltages below 300 mV. These capabilities, plus very low dropout linear regulator featuring the LT3150 its ability of maintaining stable operation with ceramic linear regulator. The DC534 generates fixed output volt- output capacitors, make the DC534 voltage regulator ages of 1.2V, 1.5V, and 1.8V, and is capable of delivering ideally suited for low Vin to Vout applications, such as 4A (max.) of output current. With the LT3150 driving microprocessor power supplies. external N-channel MOSFETs as source followers, the Design files for this circuit board are available. Call DC534 can produce very fast transient response. The the LTC factory. proper selection of the Rds(on) of the MOSFETs allows Table 1. Performance Summary PARAMETER CONDITION VALUE Minimum Input Voltage 1.1V Maximum Input Voltage 10V V V = 1.5V, I = 0A to 4A 1.2V 2% OUT1 IN OUT1 V V = 1.8V, I = 0A to 4A 1.5V 2% OUT2 IN OUT2 V V = 2.5V, I = 0A to 1.7A 1.8V 2% OUT3 IN OUT3 Typical Output Ripple I 10mV OUT(MAX) PP QUICK START PROCEDURE Demonstration circuit 534 is easy to set up to evaluate 3. For oscilloscope observations, connect a BNC cable the performance of the LT3150. Refer to Figure 1 for from the oscilloscope to connector J1, located on the proper measurement equipment setup and follow the right side of the board. procedure below: 4. Before proceeding to test, set the output voltage to NOTE: When measuring the input or output voltage rip- 1.2V, using the Output Voltage Table on the sche- ple, care must be taken to avoid a long ground lead on matic. the oscilloscope probe. Measure the input or output 5. Apply 1.5V across VIN (to GND) with 100mA of load voltage ripple by touching the probe tip directly across current. Measure V it should be 1.23V 1% OUT the VIN1 or VOUT and GND terminals. See Figure 2 for (1.218V to 1.242V). proper scope probe technique. 6. Increase the load current to 4A. Measure V again OUT 1. Connect the input power supply and voltmeter to the it should be 1.22V 2% (1.205V to 1.255V). When VIN1 and GND terminals on the right side of the finished, return I to 100mA. OUT board. 7. Increase the input voltage to 1.8V. Change the jump- 2. Connect the load and voltmeter between the VOUT ers for an output voltage of 1.5V (again see the Out- and GND terminals on the right side of the board. put Voltage Table below). Measure V it should be OUT 1.5 1% (1.485V to 1.515V). 1 GND VIN QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 534 LOW VOLTAGE LDO LINEAR REGULATOR 8. Increase the load current to 4A. Measure V again put Voltage Table below). Measure V it should be OUT OUT it should be 1.5V 2% (1.470V to 1.530V). When fin- 1.8 1% (1.782V to 1.818V). ished, return I to 100mA. OUT 10. Increase the load current to 1.7A. Measure V OUT 9. Increase the input voltage to 2.5V. Change the jump- again it should be 1.8V 2% (1.764V to 1.836V). ers for an output voltage of 1.8V (again see the Out- When finished, return I to 100mA. OUT Figure 1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple 2