LTC3866 Datasheet, PDF (9/36 Pages) Linear Technology – Current Mode Synchronous Controller for Sub Milliohm DCR Sensing

LTC3866
Pin Functions (FE/UF)
PGND (Pin 14/Pin 11): Power Ground. Connect to the
source of the bottom N-channel MOSFET and the negative
terminals of the V_IN and INTV_CC decoupling capacitors
close to this pin.
BG (Pin 15/Pin 12): Bottom Gate Driver Output. This pin
drives the gate of the bottom N-channel MOSFET and
swings between INTV_CC or EXTV_CC and PGND.
SW (Pin 16/Pin 13): Switch Node Connection. Connect
this pin to the output filter inductor, bottom N-channel
MOSFET drain and top N-channel MOSFET source. Voltage
swing at these pins is from a Schottky diode (external)
voltage drop below ground to V_IN.
TG (Pin 17/Pin 14): Top Gate Driver Output. This is a float-
ing driver to be connected to the gate of the top N‑channel
MOSFET. The voltage swing of this pin equals to INTV_CC
superimposed over the switch node (SW) voltage.
BOOST (Pin 18/Pin 15): Boosted Top Gate Driver Supply.
The (+) terminal of the booststrap capacitor connects to
this pin. This pins swings from a diode voltage drop below
INTV_CC up to V_IN + INTV_CC.
INTV_CC (Pin 19/Pin 16): Internal 5.5V Regulator Output.
The internal control circuits are powered from this voltage.
Decouple this pin to PGND with a 4.7μF low ESR tantalum
or ceramic capacitor.
V_IN (Pin 20/Pin 17): Main Input Supply. Decouple this pin
to PGND with a capacitor (0.1μF to 1μF). For applications
where the main input power is 5V, tie the V_IN and INTV_CC
pins together.
EXTV_CC (Pin 21/Pin 18): External Supply Voltage Input.
Whenever an external voltage supply greater than 4.7V
is connected to this pin, an internal switch will close and
bypass the internal low dropout regulator, and the external
supply will power the IC. Do not exceed 6V on this pin and
ensure V_IN > V_EXTVCC at all times.
ITEMP (Pin 22/Pin 19): Temperature DCR Compensation
Input. Connect to a NTC (negative tempco) resistor placed
near the output inductor to compensate for its DCR change
over temperature. Floating this pin or tying it to INTV_CC
disables the DCR temperature compensation function.
PGOOD (Pin 23/Pin 20): Power Good Indicator Output.
Open-drain logic out that is pulled to ground when the
output exceeds the 10% regulation window, after the
internal 20μs power bad mask timer expires.
MODE/PLLIN (Pin24/Pin 21): Mode Operation or External
Clock Synchronization. Connect this pin to SGND to set
the continuous mode of operation. Connect to INTV_CC to
enable pulse-skipping mode of operation. Leaving the pin
floating will enable Burst Mode operation. A clock signal
applied to the pin will force the controller into continuous
mode of operation and synchronizes the internal oscillator.
SGND (Exposed Pad Pin 25/ Exposed Pad Pin 25): Sig-
nal Ground. This is the ground of the controller. Connect
compensation components and output setting resistors
to this ground. The exposed pad must be soldered to the
PCB ground plane.
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