DEMO MANUAL DC187/DC188 NO DESIGN SWITCHER DEMO MANUAL DC187/DC188 LT1374 Monolithic 4A Switcher 5.5V to 25V Input 3.3V or 5V Output U DESCRIPTIO Demonstration circuits DC187/DC188 are complete held devices and in larger systems, as local onboard DC/DC step-down regulators using the LT 1374, constant regulators. High frequency switching allows the use of frequency, high efficiency converter in 7-pin DD (DC187) small inductors, making these all surface mount solutions and SO-8 (DC188) packages. These circuits are primarily ideal for space-conscious systems. , LTC and LT are registered trademarks of Linear Technology Corporation. used in personal computers, disk drives, portable hand- PERFORmANCE SU ARY T = 25C, V = 10V, I = 2A, V = 3.3V (Jumper J1 inserted), SHDN pin open unless otherwise noted. A IN LOAD OUT PARAMETER CONDITIONS MIN TYP MAX UNITS Output Voltage Jumper J1 Removed (Note 1) 4.91 5.02 5.20 V Jumper J1 Inserted 3.23 3.30 3.42 V Maximum I (Note 2) 4 A LOAD Input Voltage Range (Note 3) 5.5 25 V Switching Frequency 460 500 540 kHz Output Ripple Voltage 60 mV P-P Line Regulation 5.5V to 25V 8 mV Load Regulation I = 10mA to 4A 5 mV LOAD SHDN Lockout Threshold Shutdown Option Boards 2.3 2.38 2.46 V SHDN Shutdown Threshold Shutdown Option Boards 0.15 0.37 0.6 V Synchronization Range SYNC Option Boards 580 1000 kHz Supply Current SHDN = 0V 20 A Note 1: Output voltage variations include the 1% tolerance of the Note 2: For DC188 additional thermal restrictions apply. feedback-divider network. For tighter voltage range, use higher tolerance Note 3: For operating voltages down to 4V consult LTC Marketing for resistors or a fixed 5V output device, the LT1374-5. details on the LT1506. BOARD PHOTOS DC187 DC188 1 WW UWDEMO MANUAL DC187/DC188 TYPICAL PERFOR A CE CHARACTERISTICS Temperature Rise Temperature Rise vs Time, 10V , 5V Efficiency vs Load Current DC188 IN OUT 90 90 100 V = 10V V = 10V IN IN = 4A I OUT 80 V = 5V V = 5V OUT OUT 88 DC188 80 70 86 60 DC187 60 84 50 I = 3A OUT 40 82 40 30 80 I = 2A OUT 20 20 78 I = 1A OUT 10 76 0 0 2 0 12 3 4 0 1 3 4 0 10 20 30 LOAD CURRENT (A) LOAD CURRENT (A) TIME (SECONDS) 187/88 TA01 187/88 TA02 187/88 TA03 PACKAGE A D SCHE ATIC DIAGRA SM DC187 D2 MMBD914LT1 C4 0.33F D3 L1 16V OPTIONAL E5 6.8H E1 V OUT V IN 3.3V/4A OR + C3 5.5V TO 25V R2 R4 + + + C5 C6 5V/4A 6 10F C7 5.36k 2.74k D1 100F 0.47F 50V OPTIONAL 1% 1% BOOST MBRD835L 10V 25V 5 3 E4 V SW IN GND J1 U1 3.3V/5V DC187 SD LT1374CR LINK E2 2* 7 SHDN FB S/D R3 GND V C 4.99k 1% 4 1 E3 GND R1 OPTIONAL C1 C2 FRONT VIEW 1500pF OPTIONAL 50V 7 FB *SYNC FUNCTION REPLACES SHDN 6 BOOST FOR LT1374CR-SYNC PARTS TAB 5 V IN IS 4 GND GND 3 V SW 2 SHDN (SYNC) 1 V C R PACKAGE 7-LEAD PLASTIC DD PAK LT1374CR (LT1374CR-SYNC) 2 EFFICIENCY (%) DIE TEMPERATURE RISE (C) DIE TEMPERATURE RISE (C) W W U UW