LTC3542 PIN FUNCTIONS (DFN/TSOT-23)VFB (Pin 1/Pin 3): Output Feedback Pin. Receives the pulse skipping mode is selected, respectively. Do not fl oat feedback voltage from an external resistive divider across this pin. The oscillation frequency can be synchronized to the output. Nominal voltage for this pin is 0.6V. an external oscillator applied to this pin and pulse skipping mode is automatically selected. VIN (Pin 2/Pin 1): Power Supply Pin. Must be closely decoupled to GND. RUN (Pin 6/Pin 4): Converter Enable Pin. Forcing this pin above 1.5V enables this part, while forcing it below 0.3V GND (Pin 3/Pin 2): Ground Pin. causes the device to shut down. In shutdown, all functions SW (Pin 4/Pin 6): Switch Node Connection to Inductor. are disabled drawing <1μA supply current. This pin must This pin connects to the drains of the internal main and be driven; do not fl oat. synchronous power MOSFET switches. GND (Pin 7, DFN Package Only): Exposed Pad. The Ex- MODE/SYNC (Pin 5/Pin 5): Mode Selection and Oscillator posed Pad is ground. It must be soldered to PCB ground Synchronization Pin. This pin controls the operation of the to provide both electrical contact and optimum thermal device. When tied to GND or VIN, Burst Mode operation or performance. BLOCK DIAGRAM SLOPE COMPENSATION VIN OSC + ICOMP VFB – – – EA + 0.6V + + ANTI- BURST SW VB SHOOT LOGIC THROUGH MODE MODE/SYNC MODE DETECT CLKIN VIN + RUN SHUTDOWN 0.6V REF IRCMP GND – 3542 BD 3542fa 6