LTC3704 UUUPI FU CTIO SRUN (Pin 1): The RUN pin provides the user with an operating frequency to an external clock. If the MODE/ accurate means for sensing the input voltage and pro- SYNC pin is connected to ground, Burst Mode operation gramming the start-up threshold for the converter. The is enabled. If the MODE/SYNC pin is connected to INTVCC, falling RUN pin threshold is nominally 1.248V and the or if an external logic-level synchronization signal is comparator has 100mV of hysteresis for noise immunity. applied to this input, Burst Mode operation is disabled When the RUN pin is below this input threshold, the IC is and the IC operates in a continuous mode. shut down and the VIN supply current is kept to a low GND (Pin 6): Ground Pin. value (typ 10μA). The Absolute Maximum Rating for the voltage on this pin is 7V. GATE (Pin 7): Gate Driver Output. ITH (Pin 2): Error Amplifier Compensation Pin. The cur- INTVCC (Pin 8): The Internal 5.20V Regulator Output. The rent comparator input threshold increases with this gate driver and control circuits are powered from this control voltage. Nominal voltage range for this pin is 0V voltage. Decouple this pin locally to the IC ground with a to 1.40V. minimum of 4.7μF low ESR tantalum or ceramic capacitor. NFB (Pin 3): Receives the feedback voltage from the external resistor divider across the output. Nominal VIN (Pin 9): Main Supply Pin. Must be closely decoupled voltage for this pin in regulation is –1.230V. to ground. FREQ (Pin 4): A resistor from the FREQ pin to ground SENSE (Pin 10): The Current Sense Input for the Control programs the operating frequency of the chip. The nomi- Loop. Connect this pin to the drain of the power MOSFET nal voltage at the FREQ pin is 0.62V. for VDS sensing and highest efficiency. Alternatively, the SENSE pin may be connected to a resistor in the source MODE/SYNC (Pin 5): This input controls the operating of the power MOSFET. Internal leading edge blanking is mode of the converter and allows for synchronizing the provided for both sensing methods. 3704fb 6