DEMO MANUAL DC237/DC238 NO-DESIGN SWITCHER LT1506 Monolithic 4A Switcher 5V to 15V Input 3.3V Output U DESCRIPTIO Demonstration circuits DC237/DC238 are complete handheld devices and, in larger systems, as local onboard DC/DC step-down regulators using the LT 1506, constant regulators. High frequency switching allows the use of frequency, high efficiency converter in 7-pin DD (DC238) small inductors, making this all surface mount solution and SO-8 (DC237) packages. These circuits are primarily ideal for space conscious systems. used in personal computers, disk drives, portable , LTC and LT are registered trademarks of Linear Technology Corporation. PERFORmANCE SU ARY T = 25 C, V = 12V, I = 2A, V = 3.3V, SHDN and SYNC pins open, unless otherwise specified. A IN LOAD OUT PARAMETER CONDITIONS MIN TYP MAX UNITS Output Voltage (Note 1) 3.23 3.3 3.42 V Maximum I (Note 2) 4 A LOAD Input Voltage Range 4.5 15 V Switching Frequency 460 500 540 kHz Output Ripple Voltage 70 mV P-P Line Regulation 5V to 15V 2 mV Load Regulation I = 10mA to 4A 14 mV LOAD SHDN Lockout Threshold 2.3 2.38 2.46 V SHDN Shutdown Threshold 0.15 0.37 0.6 V Synchronization Range DC237 Only 580 1000 kHz Supply Current SHDN = 0V 20 m A Note 1: Output voltage variations include 1% tolerance of feedback Note 2: For DC237, additional thermal restrictions apply. divider network. For tighter voltage range, use lower tolerance resistors or fixed 3.3V output device, LT1506-3.3. BOARD PHOTOS DC237 Component Side DC238 Component Side 1 WW UWDEMO MANUAL DC237/DC238 NO-DESIGN SWITCHER TYPICAL PERFOR A CE CHARACTERISTICS 3.3V Output Efficiency Temperature Rise vs Load Current 90 120 V = 5V IN V = 3.3V OUT 88 100 5V IN DC237 86 80 12V IN 84 DC238 60 82 40 80 20 78 76 0 0 12 3 4 0 12 3 4 LOAD CURRENT (A) LOAD CURRENT (A) DC237/38TA01 DC237/38TA02 PACKAGE A D SCHE ATIC DIAGRA SM DC237 D2* MMBD914LT1 C4 1F D3* L1 10V OPTIONAL 6.8H E1 E5 V V IN OUT TOP VIEW 5V TO 15V + + + + 3.3V/4A C3 C5 C6 2 C7 D1 10F 100F 0.47F V 1 8 V OPTIONAL IN SW MBRD835L 25V BOOST 10V 10V 1 8 E4 V SW BOOST 2 7 SYNC IN U1 GND R2 FB OR LT1506CS8 3 6 SHDN 1.82k E2 6 7 E6 SENSE SHDN SYNC 1% SHDN SYNC 3 GND 4 5 V C FB GND V R3 C E3 S8 PACKAGE 4.99k GND 4 5 8-LEAD PLASTIC SO 1% DC237 SCHEM R1 LT1506CS8 C1 OPTIONAL *MOVE D2 TO POSITION D3 1500pF FOR OUTPUT CURRENTS >3A C2 50V OPTIONAL DC238 D2* MMBD914LT1 C4 1F D3* L1 10V OPTIONAL 6.8H E1 E5 V V IN OUT 5V TO 15V + C5 + 3.3V/4A + C3 + C6 C7 6 D1 100F 10F 0.47F OPTIONAL MBRD835L 25V 10V BOOST 10V 5 3 E4 V SW R2 IN GND U1 1.82k FRONT VIEW LT1506CR 1% 2 E2 7 7 FB OR SENSE SHDN FB SHDN 6 BOOST R3 GND V C V TAB 5 IN E3 4.99k IS 4 GND 4 1 GND 1% GND 3 V SW DC238 SCHEM 2 SYNC OR SHDN R1 C1 1 V OPTIONAL C *MOVE D2 TO POSITION D3 1500pF C2 FOR OUTPUT CURRENTS >3A 50V R PACKAGE OPTIONAL 7-LEAD PLASTIC DD PAK LT1506CR 2 EFFICIENCY (%) DIE TEMPERATURE RISE (C) W WU UW