LTC3631 Typical perForMance characTerisTicsSoft-Start WaveformLoad Step Transient ResponseShort-Circuit Response OUTPUT OUTPUT VOLTAGE VOLTAGE 50mV/DIV 2V/DIV OUTPUT VOLTAGE 1V/DIV LOAD INDUCTOR CURRENT CURRENT 50mA/DIV 100mA/DIV C 3631 G19 SS = 0.047µF 5ms/DIV 1ms/DIV 3631 G20 VIN = 24V 200µs/DIV 3631 G21 VIN = 10V VOUT = 5V VOUT = 5V pin FuncTions SW (Pin 1): Switch Node Connection to Inductor. This VOUT/VFB (Pin 6): Output Voltage Feedback. For the fixed pin connects to the drains of the internal power MOSFET output versions, connect this pin to the output supply. For switches. the adjustable version, an external resistive divider should V be used to divide the output voltage down for comparison IN (Pin 2): Main Supply Pin. A ceramic bypass capacitor should be tied between this pin and GND (Pin 8). to the 0.8V reference. IHYST (Pin 7): Run Hysteresis Open-Drain Logic Output. SET (Pin 3): Peak Current Set Input. A resistor from this pin to ground sets the peak current trip threshold. Leave This pin is pulled to ground when RUN (Pin 5) is below floating for the maximum peak current (225mA). Short 1.2V. This pin can be used to adjust the RUN pin hysteresis. this pin to ground for the minimum peak current (50mA). See Applications Information. A 1µA current is sourced out of this pin. GND (Pin 8, Exposed Pad Pin 9): Ground. The exposed SS (Pin 4) : Soft-Start Control Input. A capacitor to ground pad must be soldered to the printed circuit board ground at this pin sets the ramp time to full current output dur- plane for optimal electrical and thermal performance. ing start-up. A 5µA current is sourced out of this pin. If left floating, the ramp time defaults to an internal 0.75ms soft-start. RUN (Pin 5): Run Control Input. A voltage on this pin above 1.2V enables normal operation. Forcing this pin below 0.7V shuts down the LTC3631, reducing quiescent current to approximately 3µA. 3631fe 6 For more information www.linear.com/LTC3631 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Application Related Parts