DC1368A Analog Devices

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1368A ADJUSTABLE LDO LINEAR REGULATORS IN PARALLEL LT3080EDD-1 DESCRIPTION Demonstration circuit 1368A shows adjustable linear can be used as a high current linear regulator, post regulators in parallel using LT3080-1. Architected as regulator for switching supply, variable voltage sup- a precision current source and voltage follower, it ply or low output voltage power supply. allows this new regulator to be used in many applica- Internal protection circuitry includes current limiting tions requiring high current, adjustability to zero out- and thermal limiting. put, and no heat sink. Also the device brings out the LT3080-1 regulator is offered in 8-lead MSOP (with collector of the pass transistor to allow low dropout an Exposed Pad for better thermal characteristics) operation when used with multiple supplies. and a 3mm 3mm DFN. A key feature of the LT3080-1 is the capability to The LT3080-1 datasheet gives a complete description supply a wide output voltage range. By using a refer- of the part, operation and application information. ence current through a single resistor, the output The datasheet should be read in conjunction with this voltage can be programmed to any level between quick start guide for working on or modifying the zero and 36V. The DC1368A has a reduced input demo circuit 1368A. voltage 25V due to input capacitor voltage rating. LT3080-1 incorporates an internal ballast resistor to Design files for this circuit board are available. allow direct paralleling of devices without the need Call the LTC factory. for PC board resistors or sensor resistors. By direct , LTC and LT are registered trademarks of Linear Technology Corporation. paralleling of four LT3080-1 regulators, the DC1368A is capable of delivering up to 4.4A output current. It o Table 1. Performance Summary ( T = 25 C ) A PARAMETER CONDITION VALUE Minimum Vin Voltage Vout=1.2V 1.7V Maximum Vin Voltage 25V Minimum Vcontrol Voltage Vout=1.2V 2.8V Maximum Vcontrol Voltage 25V Output Voltage Iout=4.4A 1.17V 3% Minimum Output Current 4mA Maximum Output Current Vin-Vout<2.5V 4.4A 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1368A ADJUSTABLE LDO LINEAR REGULATORS IN PARALLEL QUICK START PROCEDURE The DC1368A is easy to set up to evaluate the per- 2. Vary Vin from 1.7V to 25V, Vcontrol from formance of the LT3080-1. Refer to Figure 1. for 2.8V to 25V and the load current from 4mA to proper measurement equipment setup and following 4.4A. Vout should measure 1.19V 5% the procedures below: (1.13V to 1.25V). 1. Apply 1.7V across Vin (to Gnd), and 2.8V Note: Make sure the power dissipation is limited be- across Vcontrol. Draw 4.4A of load current. low the thermal limit. The measured Vout should be 1.17V 3% (1.13V to 1.21V). Figure 1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple INPUT VOLTAGE RANGE 2