LT3509 block DiagraM COMMON 1 OF 2 REGULATOR CHANNELS SHOWN CIRCUITRY VIN BD C1 NOTE: THE BD PIN OVERVOLTAGE BOOST DETECT IS COMMON TO DIODE BOTH CHANNELS BOOST RUN/SS1 SHUTDOWN MAIN CURRENT AND COMPARATOR POWER SOFT-START SWITCH CONTROL C4 SWITCH SWITCH RUN/SS2 LOGIC DRIVER C3 L1 SW VOUT DA CURRENT C2 VREF AND COMPARATOR CORE –17mV D1 VOLTAGE V DA C C5 REGULATOR – SYNC ERROR R1 SLOPE 18mΩ AMPLIFIER VREF OSCILLATOR 0.8V RT FB CLAMP R2 RT GND 3509 BD Figure 1. Functional Block Diagram 3509fd For more information www.linear.com/LT3509 7 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Related Parts