LTC3636/LTC3636-1 PIN FUNCTIONSVIN2 (Pins 15, 16): Power Supply Input for Channel 2. PGOOD1 (Pin 27): Channel 1 Open-Drain Power Good This input is capable of operating from a separate supply Output Pin. PGOOD1 is pulled to ground when the voltage voltage than VIN1. on the VFB1 pin is not within ±8% (typical) of the internal SW1 (Pins 20, 24): Channel 1 Switch Node Connection 0.6V reference. PGOOD1 becomes high impedance once to External Inductor. Voltage swing of SW is from a diode the VFB1 pin returns to within ±5% (typical) of the internal voltage drop below ground to V reference. IN. VVIN1 (Pins 21, 22): Power Supply Input for Channel 1. FB1 (Pin 28): Channel 1 Output Feedback Voltage Pin. Input voltage to the on chip power MOSFETs on channel 1. Input to the error amplifier that compares the feedback The internal LDO for INTV voltage to the internal 0.6V reference voltage. Connect this CC is powered off of this pin. pin to a resistor divider network to program the desired BOOST1 (Pin 23): Boosted Floating Driver Supply for output voltage. Channel 1. The (+) terminal of the bootstrap capacitor connects to this pin while the (–) terminal connects to INTVCCT (Pin 29): Additional INTVCC pin. Not required to the SW pin. The normal operational voltage swing of this be connected to INTVCC pin for operation. pin ranges from a diode voltage drop below INTVCC up GNDT (Pins 30, 31, 32): Power Ground. Additional power to VIN + INTVCC. ground pins for improved thermal dissipation when con- TRACKSS1 (Pin 26): Output Tracking and Soft-Start Input nected to the GND pins. Not required to be connected to Pin for Channel 1. Forcing a voltage below 0.6V on this pin GND pins for operation. bypasses the internal reference input to the error amplifier. SWT1T ( Pin 33): Additional SW1 pin. Not required to be The LTC3636/LTC3636-1 will servo the FB pin to the TRACK connected to SW1 pins 20 and 24 for operation. voltage. Above 0.6V, the tracking function stops and the SWT2T (Pins 34): Additional SW2 pin. Not required to be internal reference resumes control of the error amplifier. connected to SW2 pins 13 and 17 for operation. An internal 1.4μA pull up current from INTVCC allows a soft-start function to be implemented by connecting a capacitor between this pin and PGND. 3636fb For more information www.linear.com/LTC3636 9 Document Outline Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Operation Applications Information Package Description Typical Application Related Parts