Analog Devices LINEAR LT8491 Manual page 11

PIN FUNCTIONS
SYNC (Pin 21): To synchronize the switching frequency
to an outside clock, simply drive this pin with a clock. The
high voltage level of the clock needs to exceed 1.3V, and
the low level should be less than 0.5V. Drive this pin to
less than 0.5V to revert to the internal free-running clock
(OSC1 in the Block Diagram).
RT (Pin 22): Timing Resistor Pin. Adjusts the switching
regulator frequency (OSC1) when SYNC is not driven by
a clock. Place a resistor from this pin to ground to set
the free-running frequency of OSC1. Do not float this pin.
BG1, BG2 (Pin 23/Pin 25): Bottom Gate Drive. Drives the
gates of the bottom N-channel MOSFETs between ground
and GATEV .
CC
GATEV (Pin 24): Power Supply for Gate Drivers. Must
CC
be connected to the INTV
other supply. Locally bypass to ground.
BOOST1, BOOST2 (Pin 33/Pin 27): Boosted Floating
Driver Supply. The (+) terminal of the bootstrap capacitor
connects here. The BOOST1 pin swings from a diode volt-
age below GATEV up to V
CC
pin swings from a diode voltage below GATEV
V + GATEV .
BAT CC
SW1, SW2 (Pin 31/Pin 29): Switch Nodes. The (–) termi-
nal of the bootstrap capacitors connect here.
TG1, TG2 (Pin 32/Pin 28): Top Gate Drive. Drives the
top N-channel MOSFETs with voltage swings equal to
GATEV superimposed on the switch node voltages.
CC
SRVO_FBIN (Pin 35): Open-Drain Logic Output. This pin
is pulled to ground when the input voltage feedback loop
is active. This pin is unused for most LT8491 applications
and can be floated.
SRVO_IIN (Pin 36): Open-Drain Logic Output. This pin is
pulled to ground when the input current feedback loop is
active. This pin is unused for most LT8491 applications
and can be floated.
SRVO_IOUT (Pin 37): Open-Drain Logic Output. This pin
is pulled to ground when the output current feedback loop
is active. This pin is unused for most LT8491 applications
and can be floated.
pin. Do not power from any
CC
+ GATEV . The BOOST2
IN CC
CC
For more information
SRVO_FBOUT (Pin 38): Open-Drain Logic Output. This
pin is pulled to ground when the output voltage feedback
loop is active. This pin is unused for most LT8491 applica-
tions and can be floated.
EXTV (Pin 40): External V
CC
exceeds 6.4V (typical), INTV
pin. When EXTV
will be powered from V
Current Conduction Mode for additional details.
CSNOUT (Pin 41): The (–) Input to the Output Current
Sense Amplifier.
CSPOUT (Pin 42): The (+) Input to the Output Current
Sense Amplifier. This pin and the CSNOUT pin measure
the voltage across the sense resistor to provide the output
current signals.
CSNIN (Pin 44): The (–) Input to the Input Current Sense
Amplifier. This pin and the CSPIN pin measure the voltage
across the sense resistor to provide the instantaneous
input current signals.
CSPIN (Pin 45): The (+) Input to the Input Current Sense
up to
Amplifier.
V (Pin 46): Main Input Supply Pin. Must be bypassed
IN
to local ground plane.
ECON (Pin 48): Digital Output Pin. Optional control output
signal used to disconnect EXTV
the average charge current drops below a predetermined
threshold.
SWENO (Pin 49): Digital Output Pin. Connect to SWEN.
Enables the switching regulator. A 200k pull-down resistor
is required from this pin to ground.
IOW (Pin 50): Digital Output Pin. Connects to IMON_OUT
through a resistor. By switching the pin between logic low
and high impedance, the total R
changes the output current limit.
STATUS (Pin 51): Digital Output Pin. When used with an
LED, this signal provides a visual indication of the prog-
ress of the charging algorithm.
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Input. When EXTV
CC
will be powered from this
CC
is lower than 6.22V (typical), INTV
CC
. See HW Config: MODE Pin -
IN
from the battery when
CC
changes, which
IMON_OUT
LT8491
CC
CC
Rev. 0
11