LTC3810-5 pin FuncTionsBG (Pin 18): Bottom Gate Drive. The BG pin drives the TG (Pin 26): Top Gate Drive. The TG pin drives the gate of gate of the bottom N-channel synchronous switch MOSFET. the top N-channel synchronous switch MOSFET. The TG This pin swings from BGRTN to DRVCC. driver draws power from the BOOST pin and returns to the BGRTN (Pin 19): Bottom Gate Return. This pin connects to SW pin, providing true floating drive to the top MOSFET. the source of the pulldown MOSFET in the BG driver and BOOST (Pin 27): Top Gate Driver Supply. The BOOST pin is normally connected to ground. Connecting a negative supplies power to the floating TG driver. BOOST should supply to this pin allows the synchronous MOSFET ’s gate be bypassed to SW with a low ESR (X5R or better) 0.1µF to be pulled below ground to help prevent false turn-on capacitor. An additional fast recovery Schottky diode from during high dV/dt transitions on the SW node. See the DRVCC to the BOOST pin will create a complete floating Applications Information section for more details. charge-pumped supply at BOOST. SENSE+, SENSE– (Pin 24, Pin 20): Current Sense Com- ION (Pin 31): On-Time Current Input. Tie a resistor from VIN parator Input. The (+) input to the current comparator is to this pin to set the one-shot timer current and thereby normally connected to SW unless using a sense resistor. set the switching frequency. The (–) input is used to accurately kelvin sense the bottom SGND (Exposed Pad Pin 33): Signal Ground. All small- side of the sense resistor or MOSFET. signal components should connect to this ground and SW (Pin 25): Switch Node Connection to Inductor and eventually connect to PGND at one point. Bootstrap Capacitor. The voltage swing at this pin is –0.7V (a Schottky diode (external) voltage drop) to VIN. 38105fd 10 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts