QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC683 1.2MHZ BOOST DC/DC CONVERTER IN THINSOT WITH 2A SWITCH LT1935ES5 DESCRIPTION Demonstration circuit DC683 features LT1935 1.2MHz boost dc/dc converter with 2A switch. The circuit in DC683 is designed to generate 12V output from a 3.3V to 5.5V input voltage range. The maximum output current is listed on the DC683 silkscreen along with the input voltage range. The boost converter circuit is enabled using JP1. Placing the jumper to “OFF” activates the SHDN pin of the boost converter. Jumper to “ON” en- ables the boost converter and will bring the output up to 12V. The SHDN pin is also accessible via J5 (turret). Design files for this circuit board are available. Call the LTC factory. ________________________________________________ LT is a trademark of Linear Technology Corporation Table 1. Performance Summary (TA = 25°C unless otherwise noted) PARAMETER FOR BOOST CONVERTER CONDITION VALUE Minimum Input Voltage For DC683 (IC datasheet spec. 2.3V) 3.3V Maximum Input Voltage For DC683 (IC datasheet spec. 16V) 5V Maximum Output Current 12V output with 5V input 600mA Typical Efficiency 5V input to 12V output with 200mA~600mA load 86% Output voltage ripple 5V input to 12V output with 600mA load 75mV Switching frequency 5V input to 12V output with 600mA load 1.2MHz QUICK START PROCEDURE Demonstration circuit 683 is easy to set up to evaluate the performance of the LT1935. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 1. With power off, connect the input power supply to Vin and GND. Make sure JP1 is set to “ON”. 2. Set the input supply between 3.3V to 5V. Turn on the power at the input and observe the output voltage across VOUT and GND. The output voltage should read ≅ 12V. 3. Turn on the load (follow the chart on the demo board silkscreen for input voltage and output current, 400mA maximum current with 3.3V input and 600mA maximum current with 5V input voltage). The output voltage should be regulating to ≅ 12V under varying load conditions. 4. Test the SHDN function by placing the jumper JP1 to “OFF”. The LT1935 should stop switching and the output voltage should read ≅ 0.3V below the input voltage. Enable the boost converter by placing the jumper (J1) back to “ON.” The output should now read ≅ 12V. 5. Check the output ripple using the oscilloscope (refer to figure 2). The output ripple should not be greater than 100mV. Also check the switching frequency, it should be ≅ 1.2MHz. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC683 1.2MHZ BOOST DC/DC CONVERTER IN THINSOT WITH 2A SWITCH Figure 1. Proper Measurement Equipment Setup Figure2. Measuring Input or Output Ripple 2 5 D 4 3 2 This circuit is proprietary to Linear Technology and supplied for use with Linear Technology parts. Customer Notice:Linear Technology has made a best effort to design a circuit that meets customer-supplied specifications; however, it remains the customers responsibility to verify proper and reliable operation in the actual application, Component substitution and printed circuit board layout may significantly affect circuit performance or reliability. Contact Linear Applications Engineering for assistance. ECO 2 OFF 1 R3 SHDN J5 4 SHDN C3 10K 12V [1] VOUT UPS120 0.1uF LT1935ES5 SW 1 2 JP1 U1 GND 0805 ON VOUT APPROVED 01/26/04 D1 1A 1 C2 POWERMITE J3 10uF R2 C4 86.6K 10pF 0603 0603 1206 C FB 3 R1 10K 2 10V C 3 VIN 5 4.7uF DATE PROTO 3.3uH TDK SLF7028T-3R3M1R6 C1 DESCRIPTION D VIN J1 REV 2 L1 3.3V-5V 1 REVISION HISTORY 0603 GND GND J4 J2 B B [1] VIN VOUT 3.3V 12V @ 400mA 5V 12V @ 600mA CONTRACT NO. APPROVALS DRAWN MEI CHECKED A DATE 05/01/03 TECHNOLOGY TITLE 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 Fax: (408)434-0507 SCH, LT1935ES5 BOOST CONVERTER A APPROVED ENGINEER DESIGNER Friday, February 06, 2004 5 4 3 SIZE CAGE CODE SCALE: DWG NO FILENAME: 683A-2.DSN 2 REV DC683A SHEET 2 1 1 OF 1 Linear Technology Corporation LT1935ES5 Item 1 2 3 4 5 6 7 8 9 10 11 12 Qty 1 1 1 1 1 1 5 1 1 1 1 1 Ref C1 C2 C3 C4 D1 JP1 J1,J2,J3,J4,J5 L1 R1 R2 R3 U1 DC683A Rev 2 6/20/2005 Parts List Desc CAP, X7R 4.7uF 10V 20% 0805 CAP, X7R 10uF 16V 20% 1206 CAP, X7R 0.1uF 10V 20% 0603 CAP, COG 10pF 50V 5% 0603 DIODE,SCHOTTKY 20V 1A HEADER,3PIN, 2mm TURRET IND, 3.3uH RES, 10K OHMS 1% 1/16W 0603 RES, 86.6KK OHMS 1% 1/16W 0603 RES, 10K OHMS 5% 1/16W 0603 IC, LT1935ES5 1 of 1 Manufacturer / Part # TDK C2012X7R1A475M TDK C3216X7R1C106M AVX 0603ZC104MAT AVX 06035A100JAT2A MICROSEMI UPS120 COMM CON 2802S-03G2 MILL-MAX 2501-2 TDK SLF7028T-3R3M1R6 AAC CR16-1002FM AAC CR16-8662FM AAC CR16-103JM LINEAR TECH. LT1935ES5