DEMO MANUAL DC143 NO DESIGN SWITCHER DEMO MANUAL DC143 LTC1474/LTC1475 10A I , High Efficiency, Q Step-Down DC/DC U Converter DESCRIPTIO This demonstration circuit is a step-down (buck) regulator 10A (typical) is required to regulate the output. The parts using the LTC 1474/LTC1475. The exclusive use of surface can be shut down to further reduce the supply current to mount components and the LTC1474/LTC1475 in the tiny 6A (typical). In dropout, the internal P-channel MOSFET MSOP package results in a highly efficient application in a is turned on continuously (100% duty cycle), providing small board space. This demo board highlights the low dropout operation with V V . An onboard low- OUT IN capabilities of the LTC1474/LTC1475, which use a current battery detector allows the user to monitor the input mode, constant off-time architecture to switch an internal supply through an external resistive divider. This board is P-channel power MOSFET. This results in a power supply intended for applications such as cellular phones, GSM that has low ripple and fast transient response. At low systems, 4mA to 20mA current-loop pirate supplies or any output currents the LTC1474/LTC1475 automatically portable battery-powered application. Gerber files for this TM switch to Burst Mode operation to maintain high operating circuit board are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. efficiencies and minimize supply current. At no load,only Burst Mode is a trademark of Linear Technology Corporation. PERFORmANCE SU ARY SYMBOL PARAMETER CONDITIONS BOARD SUFFIX VALUE V Input Voltage Range V = 3.3V A, B, D, E 3.3V to 18V IN OUT V = 5V C, F 5V to 18V OUT V Output Voltage LTC1474/LTC1475 A, D 3.3V 0.10V OUT LTC1474-3.3/LTC1475-3.3 B, E 3.3V 0.10V LTC1474-5/LTC1475-5 C, F 5V 0.15V I Maximum Output Current R = 0 ALL 300mA OUT SENSE R = 0.25 ALL 150mA SENSE I Typical Supply Current V = 10V, I = 0 A, B, C 10A Q IN LOAD V = 10V, I = 0 D, E, F 15A IN LOAD W U U TYPICAL PERFOR A CE CHARACTERISTICS A D BOARD PHOTO Demo Board D Board A, B, D, E Efficiency Demo Board A 100 V = 5V IN 90 V = 10V IN 80 V = 15V IN 70 60 L = 100H V = 3.3V OUT R = 0 SENSE 50 DM143 DB D DM143 DB A 0.03 0.3 3 30 300 LOAD CURRENT (mA) DM143 TPC 1 EFFICIENCY (%) WW UWDEMO MANUAL DC143 PERFORmANCE SU ARY SYMBOL PARAMETER CONDITIONS BOARD SUFFIX VALUE V Typical Output Ripple I = 100mA All 50mV RIPPLE OUT V Typical Line Regulation 4V < V < 18V, R = 0, I = 100mA A, D 35mV OUT IN SENSE LOAD 4V < V < 18V, R = 0.25, I = 100mA 25mV IN SENSE LOAD 4V < V < 18V, R = 0, I = 100mA B, E 20mV IN SENSE LOAD 4V < V < 18V, R = 0.25, I = 100mA 10mV IN SENSE LOAD 6V < V < 18V, R = 0, I = 100mA C, F 20mV IN SENSE LOAD 6V < V < 18V, R = 0.25, I = 100mA 10mV IN SENSE LOAD Typical Load Regulation 0 < I < 300mA, R = 0, V = 10V All 10mV LOAD SENSE IN 0 < I < 150mA, R = 0.25, V = 10V 10mV LOAD SENSE IN V Low-Battery Trip Threshold All 1.23V LBI PACKAGE A D SCHE ATIC DIAGRA SM TOP VIEW THIS NETWORK V (V *) 1 8 RUN OUT FB V C3 IN IS PRESENT IN LBO 2 7 V IN 4V* TO 18V 10pF BOARD A ONLY C1 LBI 3 6 SENSE C2 C5 4.7F R6 R1 GND 4 5 SW 1000pF 0.1F 7 35V 0 0.25 V MS8 PACKAGE IN R5 V OUT 1 6 3.3V 8-LEAD PLASTIC MSOP SENSE V FB + C4 300mA 3 2 L1 R4 100F LTC1474 *ADJUSTABLE OUTPUT VERSION LBI LBI LBO 100H 6.3V 8 5 LTC1474CMS8 RUN SW GND R7 LTC1474CMS8-3.3 D1 JP1 100k 4 MBR0530 RUN LTC1474CMS8-5 *3.3V AT NO LOAD LBO DM143 F01 Figure 1. LTC1474 Demo Board Schematic TOP VIEW THIS NETWORK V C3 V (V *) 1 8 ON IN OUT FB IS PRESENT IN 4V* TO 18V 10pF LBO 2 7 V BOARD D ONLY IN C1 C2 C5 LBI/OFF 3 6 SENSE 4.7F R6 R1 1000pF 0.1F 7 5 SW GND 4 35V 0 0.25 V IN R5 V OUT 1 6 MS8 PACKAGE R3 SENSE V 3.3V FB 8-LEAD PLASTIC MSOP + 3.01M LTC1475 C4 300mA 3 2 L1 100F R4 LBI LBI/OFF LBO *ADJUSTABLE OUTPUT VERSION 100H 6.3V R2 8 5 1M SHDN ON SW LTC1475CMS8 GND R7 D1 LTC1475CMS8-3.3 RUN 100k 4 MBR0530 LTC1475CMS8-5 LBO *3.3V AT NO LOAD DM143 F02 Figure 2. LTC1475 Demo Board Schematic 2 + + W W U WW UW