DEMO C IR C U IT 1 1 7 2 A Q U IC K S TAR T GLT1965 U IDE L T 1 9 6 5 EDD 1 .1 A L o w Dro p o u t R e g u la to r DESCRIPTION Demonstration circuit 1172A is a low dropout linear regulator featuring LT®1965, w hich comes in 5-lead TO -220, 5-lead DD-PAK as w ell as the thermally enhanced 8-lead M SO P and 8-lead 3mmX3mm DFN packages. The DC1172A has an input voltage range from 2.3 to 20V, and is capable of delivering up to 1.1A output current. O perating quiescent current is 500µA, reducing to less than 1µA in shutdow n. The DC1172A has a very low output noise,w hich makes it ideal for logic pow er supplies, post regulator for sw itching supplies and low noise instruments. The LT1965 datasheet gives a complete description of the part,operation and application information. The datasheet must be read in conjunction w ith this quick start guide for demo circuit 1172A. Design files for this circuit board are available. Call the LTC factory. ,LTC and LT are registered trademarks ofLinear Technology Corporation. ThinSOT and Pow erPath are trademarks ofLinear Technology Corporation. Perform ance Sum m ary ( TA = 25oC ) PAR AM ETER FO R BU CK R EG ULATO R M inimum Input Voltage M aximum Input Voltage O utput Voltage Vout CO N DITIO N VIN =2.5V,IOUT=1.1A VIN =2.5V,IOUT=1.1A VIN =2.5V,IOUT=1.1A VIN =3.3V,IOUT=1.1A VIN =3.3V,IOUT=1.1A M aximum O utput Current VALU E 2.3V 20V 1.2V +/- 4% 1.5V +/- 4% 1.8V +/- 4% 2.5V +/- 4% 3.3V +/- 4% 1.1A Q U ICK STA RT PROCEDU RE Demonstration circuit 1172A is easy to set up to evaluate the performance of the LT1965. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below : 1. Before proceeding to test, insert jumper JP1 into the O FF position, and use VO U T Select jumper J1 for the desired output voltage 1.2V, 1.5V,1.8V, 2.5V, 3.3V. If the output voltage is different from the above values, use the U SER select option and install a resistor R 5. 2. Apply input voltage across Vin to G nd. Insert jumper JP1 into the O N position. Check for the proper output voltage. 3. Once the proper output voltage is established, adjust the load w ithin the operating range and observe the output voltage regulation. 1 LT1965 Figure 1. Proper M easurem ent Equipm ent Setup Figure 2. M easuring Input or Output R ipple 2 LT1965 3