LM5642XMT National Semiconductor, LM5642XMT Datasheet - Page 3

• Manufacturer Part Number: LM5642XMT
• Description: IC,SMPS CONTROLLER,CURRENT-MODE,TSSOP,28PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LM5642XMT

• Rohs Compliant: NO

RSNS2 (Pin 15): The negative (-) Kelvin sense for the internal
current sense amplifier of Channel 2. Connect this pin to the
low side of the current sense resistor that is placed between
VIN and the drain of the top MOSFET. When the 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 driv-
er, 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 resis-
tor and bypassed to power ground with a ceramic capacitor
of at least 1µF. Tie this pin to VDD1 (Pin 24).
LDRV2 (Pin 20): Low-side gate-drive output for Channel 2.
3
PGND (Pin 21): The power ground connection for both chan-
nels. 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 con-
nected 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. This pin
serves as the positive supply rail for the 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).
PGND (DAP): The power ground connection for both chan-
nels. Connect to the ground rail of the system. Use of multiple
vias to internal ground plane or GND layer helps to dissipate
heat generated by output power.
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