LM5642
Pin Descriptions
(Continued)
Rds of the top MOSFET is used for current sensing, connect
this pin to the source of the top MOSFET. Always use a
separate trace to form a Kelvin connection to this pin.
SW2 (Pin 16):
Switch-node connection for Channel 2, which
is connected to the source of the top MOSFET of Channel 2.
It serves as the negative supply rail for the top-side gate
driver, HDRV2.
HDRV2 (Pin 17):
Top-side gate-drive output for Channel 2.
HDRV is a floating drive output that rides on the correspond-
ing switching-node voltage.
CBOOT2 (Pin 18):
Bootstrap capacitor connection. It serves
as the positive supply rail for the Channel 2 top-side gate
drive. Connect this pin to VDD2 (Pin 19) through a diode,
and connect the low side of the bootstrap capacitor to SW2
(Pin16).
VDD2 (Pin 19):
The supply rail for the Channel 2 low-side
gate drive. Connected to VLIN5 (Pin 7) through a 4.7Ω
resistor and bypassed to power ground with a ceramic ca-
pacitor of at least 1µF. Tie this pin to VDD1 (Pin 24).
LDRV2 (Pin 20):
Low-side gate-drive output for Channel 2.
PGND (Pin 21):
The power ground connection for both
channels. Connect to the ground rail of the system.
VIN (Pin 22):
The power input pin for the chip. Connect to
the positive (+) input rail of the system. This pin must be
connected to the same voltage rail as the top FET drain (or
the current sense resistor when used).
LDRV1 (Pin 23):
Low-side gate-drive output for Channel 1.
VDD1 (Pin 24):
The supply rail for Channel 1 low-side gate
drive. Tie this pin to VDD2 (Pin 19).
CBOOT1 (Pin 25):
: Bootstrap capacitor connection. It
serves as the positive supply rail for Channel 1 top-side gate
drive. See CBOOT2 (Pin 18).
HDRV1 (Pin 26):
Top-side gate-drive output for Channel 1.
See HDRV2 (Pin 17).
SW1 (Pin 27):
Switch-node connection for Channel 1. See
SW2 (Pin16).
RSNS1 (Pin 28):
The negative (-) Kelvin sense for the
internal current sense amplifier of Channel 1. See RSNS2
(Pin 15).
3
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