LTC3636/LTC3636-1 PIN FUNCTIONS the SW pin. The normal operational voltage swing of this and the internal reference resumes control of the error pin ranges from a diode voltage drop below INTVCC up amplifier. An internal 1.4μA pull up current from INTVCC to VIN+INTVCC. allows a soft-start function to be implemented by connect- V ing a capacitor between this pin and PGND. IN2 (Pins 15, 16): Power Supply Input for Channel 2. This input is capable of operating from a separate supply PGOOD1 (Pin 27): Channel 1 Open-Drain Power Good voltage than VIN1. Output Pin. PGOOD1 is pulled to ground when the voltage SW1 (Pins 20, 24): Channel 1 Switch Node Connection on the VFB1 pin is not within ±8% (typical) of the inter- to External Inductor. Voltage swing of SW is from a diode nal 0.6V reference. PGOOD1 becomes high impedance voltage drop below ground to V once the V IN. FB1 pin returns to within ±5% (typical) of the internal reference. VIN1 (Pins 21, 22): Power Supply Input for Channel 1. Input voltage to the on chip power MOSFETs on channel 1. VFB1 (Pin 28): Channel 1 Output Feedback Voltage Pin. The internal LDO for INTV Input to the error amplifier that compares the feedback CC is powered off of this pin. voltage to the internal 0.6V reference voltage. Connect this BOOST1 (Pin 23): Boosted Floating Driver Supply for pin to a resistor divider network to program the desired Channel 1. The (+) terminal of the bootstrap capacitor output voltage. connects to this pin while the (–) terminal connects to the SW pin. The normal operational voltage swing of this INTVCCT (Pin 29): Additional INTVCC pin. Not required to pin ranges from a diode voltage drop below INTV be connected to INTV CC up CC pin for operation. to VIN + INTVCC. GNDT (Pins 30, 31, 32): Power Ground. Additional power TRACKSS1 (Pin 26): Output Tracking and Soft-Start Input ground pins for improved thermal dissipation when con- Pin for Channel 1. Forcing a voltage below 0.6V on this pin nected to the GND pins. Not required to be connected to bypasses the internal reference input to the error ampli- GND pins for operation. fier. The LTC3636/LTC3636-1 will servo the FB pin to the SWT1T ( Pin 33): Additional SW1 pin. Not required to be TRACK voltage. Above 0.6V, the tracking function stops connected to SW1 pins 20 and 24 for operation. SWT2T (Pins 34): Additional SW2 pin. Not required to be connected to SW2 pins 13 and 17 for operation. Rev. C For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts