LTC3810-5 Datasheet, PDF (10/36 Pages) Linear Technology – 60V Current Mode Synchronous Switching Regulator Controller

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