LM2648 datasheet(2/23 Pages) NSC

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Connection Diagram

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20059602

56-Lead TSSOP (MTD)

Order Number LM2648MTD

See NS Package Number MTD56

Pin Descriptions

SW1 (Pin 1): Switch-node connection for Channel 1, which

is connected to the source of the top MOSFET of Channel 1.

It serves as the negative supply rail for the top-side gate

drive, HDRV1.

RSNS1 (Pin 2): The negative (-) Kelvin sense for the internal

current limit comparator of Channel 1. Connect this pin to the

low side of the current sense resistor that is placed between

VIN and the drain of the top MOSFET. Always use a sepa-

rate trace to connect this pin.

ILIM1 (Pin 3): Current limit threshold setting for Channel 1. It

sinks a variable current adjusted by RILIM (Pin11), which is

converted to a voltage through a resistor connected from this

pin to the top of the current sense resistor. The voltage

across the resistor is compared with the voltage across the

external current sense resistor to determine if an over-

current condition has occurred on Channel 1.

NC (Pin 4): All NC pins should be connected to SGND.

COMP1 (Pin 5): Compensation pin for Channel 1. This is the

output of the internal error amplifier. The compensation net-

work should be connected between this pin and the feed-

back pin, FB1 (PIN 6).

FB1 (Pin 6): Feedback input for channel 1. Connect to Vout

through a voltage divider to set the channel 1 output voltage.

TEST (Pin 7): Connect to SGND.

COMP3 (Pin 8): Compensation pin for Channel 3. This is the

output of the internal transconductance amplifier. The com-

pensation network should be connected between this pin

and SGND.

FB3 (Pin 9): Feedback input for channel 3. Connect to Vout

through a voltage divider to set the Channel 3 output voltage.

NC (Pin 10): All NC pins should be connected to SGND.

RILIM (Pin 11): Connect a resistor from this pin to SGND to

set the internal ILIM reference current.

ON/UVLO (Pin 12): This is a dual function pin providing

thresholds for user adjustable UVLO and device shutdown.

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