LINEAR TECHNOLOGY PRE-RELEASE DEMO MANUAL DC(1775) LTC1775 High Power No R Stepdown Controller SENSE DESCRIPTION Demonstration Circuit (1775) is efficiencies in excess of 95% are a constant frequency stepdown (buck) readily achieved without sacrificing regulator for high power applications the advantages of current mode using the LTC1775 No R controller. control such as inherent current SENSE The regulator delivers up to 10A at limiting, excellent rejection of line fixed output voltages of 3.3V and 5V. transients, and simple compensation. The output voltage can also be At low output currents, the adjusted with an external feedback LTC1775 automatically changes to TM divider from 1.19V up to 12V. Input Burst Mode operation to reduce voltages can range from 4.5V up to switching losses and maintain high 28V. operating efficiency. Additionally, The LTC1775 controller uses a the supply current can be shut down current mode, constant frequency to less than 20uA to maximize battery architecture to switch a pair of N- life in portable applications. This channel power MOSFETs. Current mode board is intended for applications control is provided without using a such as notebook computers, sense resistor by monitoring the automotive electronics, and voltage drop across the MOSFET distributed power systems. Gerber switches in order to determine the files for this circuit board are inductor current. By eliminating the available. Call the LTC factory. power loss in the sense resistor, PERFORMANCE SUMMARY Operating Temperature Range 0C to 50C SYMBOL CONDITIONS VALUE V Input Voltage Range (Maximum input voltage limited by external MOSFET 4.5V to IN and input capacitor) 28V I Maximum Output Current 10A OUT(MAX) V Output Voltage (Jumper selectable) 3.3V, 5V OUT Output Voltage (Adjustable, limited by output capacitor) 1.19V to 12V Output Voltage Ripple at V =10V, V =5V, I =5A 50mV V IN OUT OUT OUT(RIPPLE) Output Voltage Ripple at V =10V, V =5V, I =0.5A (Burst Mode) 100mV IN OUT OUT Load Regulation, I =0A to 10A, Continuous Mode -0.2% V OUT OUT(LOADREG) Line Regulation, V =4.5V to 20V, Continuous Mode 0.05% V IN OUT(LINEREG) I Supply Current at V =10V, I =0A, FCB=INTV (Burst Mode), EXTV=5V 300uA Q IN OUT CC CC Supply Current in Shutdown at V=10V 15uA IN I EXTV Pin Current at V =10V, I =0A, FCB=INTV (Burst Mode), EXTV =5V 550uA EXTVCC CC IN OUT CC CC V RUN/SS Pin Threshold 1.4V RUN/SS f Switching Frequency, SYNC=0V 150kHz TYPICAL PERFORMANCE CHARACTERISTICS AND BOARD PHOTO CBU:manual.doc December 17, 2002 LINEAR TECHNOLOGY CONFIDENTIAL 1LINEAR TECHNOLOGY PRE-RELEASE DEMO MANUAL DC(1775) PACKAGE AND SCHEMATIC DIAGRAMS TOP VIEW (Package Drawing) S PACKAGE 16-LEAD PLASTIC SO (Schematic Drawing) CBU:manual.doc December 17, 2002 LINEAR TECHNOLOGY CONFIDENTIAL 2