LTC3720 Datasheet, PDF (7/24 Pages) Linear Technology – Single Phase VRM8.5 Current Mode Step-Down Controller

LTC3720
PI FU CTIO S
V_CC (Pin 18): Power Supply Voltage for VID. Range is from
3.1V to 5.5V.
EXTV_CC (Pin 19): External V_CC Input. When EXTV_CC ex-
ceeds 4.7V, an internal switch connects this pin to INTV_CC
and shuts down the internal regulator so that controller
and gate drive power is drawn from EXTV_CC. Do not exceed
7V at this pin and ensure that EXTV_CC < V_IN.
V_IN (Pin 20): Main Input Supply. Decouple this pin to
PGND with an RC filter (1Ω, 0.1µF).
INTV_CC (Pin 21): Internal 5V Regulator Output. The driver
and control circuits are powered from this voltage. De-
couple this pin to power ground with a minimum of 4.7µF
low ESR tantalum capacitor.
BG (Pin 22): Bottom Gate Drive. Drives the gate of the
bottom N-channel MOSFET between ground and INTV_CC.
PGND (Pin 23): Power Ground. Connect this pin closely to
the source of the bottom N-channel MOSFET, the (–)
terminal of C_VCC and the (–) terminal of C_IN.
SENSE^– (Pin 24): Current Sense Comparator Input. The
(–) input is normally connected to PGND.
SENSE ⁺ (Pin 25): Current Sense Comparator Input. The
(+) input to the current comparator is normally connected
to the SW node unless using a sense resistor (see Appli-
cations Information).
SW (Pin 26): Switch Node. The (–) terminal of the boot-
strap capacitor C_B connects here. This pin swings from a
diode voltage drop below ground up to V_IN.
TG (Pin 27): Top Gate Drive. Drives the top N-channel
MOSFET with a voltage swing equal to INTV_CC superim-
posed on the switch node voltage SW.
BOOST (Pin 28): Boosted Floating Driver Supply. The (+)
terminal of the bootstrap capacitor C_B connects here. This
pin swings from a diode voltage drop below INTV_CC up to
V_IN + INTV_CC.
3720f
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