VCC

1

SW

2

BOOT

3

LGATE

4

FB

5

HGATE

10

ILIM

9

GND

8

SS/TRACK

7

COMP/EN

6

LM3743

LM3743

SNVS427E – SEPTEMBER 2006 – REVISED APRIL 2013

www.ti.com

Connection Diagram

Figure 1. 10-Lead Plastic VSSOP (Top View)

See Package Number DGS

PIN DESCRIPTIONS

Supply rail for the controller section of the IC. A minimum capacitance of 1 µF, preferably a multi-layer

VCC (Pin 1)

1 to 4.99

Ω resistance must be connected in series from the supply rail to the Vcc pin. See VCC Filtering

in the Design Consideration section for further details.

Gate drive for the low-side N-channel MOSFET. This signal is interlocked with HGATE to avoid a shoot-

LGATE (Pin 2)

through problem.

Power ground (PGND) and signal ground (SGND). Connect the bottom feedback resistor between this

GND (Pin 3)

pin and the feedback pin.

Low side current limit threshold setting pin. This pin sources a fixed 50 µA current. A resistor of

ILIM (Pin 4)

appropriate value should be connected between this pin and the drain of the low-side N-FET.

Feedback pin. This is the inverting input of the error amplifier used for sensing the output voltage and

FB (Pin 5)

compensating the control loop.

Output of the error amplifier and enable pin. The voltage level on this pin is compared with an internally

COMP/EN (Pin 6)

generated ramp signal to determine the duty cycle. This pin is necessary for compensating the control

loop. Forcing this pin to ground will shut down the IC.

Soft-start and tracking pin. This pin is connected to the non-inverting input of the error amplifier during

SS/TRACK (Pin 7)

initial soft-start, or any time the voltage is below the reference. To track the rising ramp of another power

supply's output, connect a resistor divider from the output of that supply to this pin as described in

Application Information.

Switch pin. The lower rail of the high-side N-FET driver. Also used for the high side current limit sensing.

SW (Pin 8)

Gate drive for the high-side N-channel MOSFET. This signal is interlocked with LGATE to avoid a shoot-

HGATE (Pin 9)

through problem.

Supply rail for the N-channel MOSFET high gate drive. The voltage should be at least one gate

BOOT (Pin 10)

threshold above the regulator input voltage to properly turn on the high-side N-FET. See MOSFET

GATE DRIVE in the Application Information section for more details on how to select MOSFETs.

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

2

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