LM2743-19AEVAL National Semiconductor, LM2743-19AEVAL Datasheet - Page 2

• Manufacturer Part Number: LM2743-19AEVAL
• Description: BOARD EVALUATION LM2743-19A
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM2743-19AEVAL

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.2 ~ 3.3V
• Current - Output: 19A
• Voltage - Input: 8 ~ 14V
• Regulator Topology: Buck
• Frequency - Switching: 300kHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM2743
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

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Connection Diagram
Ordering Information
Pin Descriptions
BOOT (Pin 1) - Bootstrap pin. This is the supply rail for the
gate drivers. When the high-side MOSFET turns on, the volt-
age on this pin should be at least one gate threshold above
the regulator input voltage V
FET. See MOSFET Gate Drivers in the Application Informa-
tion section for more details on how to select MOSFETs.
LG (Pin 2) - Low-gate drive pin. This is the gate drive for the
low-side N-channel MOSFET. This signal is interlocked with
the high-side gate drive HG (Pin 14), so as to avoid shoot-
through.
PGND (Pins 3, 13) - Power ground. This is also the ground
for the low-side MOSFET driver. Both the pins must be con-
nected together on the PCB and form a ground plane, which
is usually also the system ground.
SGND (Pin 4) - Signal ground. It should be connected ap-
propriately to the ground plane with due regard to good layout
practices in switching power regulator circuits.
V
PWGD (Pin 6) - Power Good pin. This is an open drain output,
which is typically meant to be connected to V
low voltage source through a pull-up resistor. Choose the pull-
up resistor so that the current going into this pin is kept below
1 mA. For most applications a recommended value for the
pull-up resistor is 100 kΩ. The voltage on this pin is thus pulled
low under output under-voltage or over-voltage fault condi-
tions and also under input UVLO.
I
a fixed 40 µA current. A resistor of appropriate value should
be connected between this pin and the drain of the low-side
MOSFET (switch node).
SEN
CC
(Pin 5) Supply rail for the control sections of the IC.
(Pin 7) - Current limit threshold setting pin. This sources
Order Number
LM2743MTCX
LM2743MTC
IN
to properly turn on the MOS-
Package Type
TSSOP-14
TSSOP-14
CC
or any other
14-Lead Plastic TSSOP
θ
JA
= 155°C/W
2
NSC Package Drawing
EAO (Pin 8) - Output of the error amplifier. The voltage level
on this pin is compared with an internally generated ramp
signal to determine the duty cycle. This pin is necessary for
compensating the control loop.
SS/TRACK (Pin 9) - Soft-start and tracking pin. This pin is
internally connected to the non-inverting input of the error
amplifier during soft-start, and in fact any time the SS/TRACK
pin voltage happens to be below the internal reference volt-
age. For the basic soft-start function, a capacitor of minimum
value 1 nF is connected from this pin to ground. To track the
rising ramp of another power supply’s output, connect a re-
sistor divider from the output of that supply to this pin as
described in Application Information.
FB (Pin 10) - Feedback pin. This is the inverting input of the
error amplifier, which is used for sensing the output voltage
and compensating the control loop.
FREQ (Pin 11) - Frequency adjust pin. The switching fre-
quency is set by connecting a resistor of suitable value be-
tween this pin and ground. The equation for calculating the
exact value is provided in Application Information, but some
typical values (rounded up to the nearest standard values) are
324 kΩ for 100 kHz, 97.6 kΩ for 300 kHz, 56.2 kΩ for 500 kHz,
24.9 kΩ for 1 MHz.
SD (Pin 12) - IC shutdown pin. Pull this pin to V
the IC is enabled. Connect to ground to disable the IC. Under
shutdown, both high-side and low-side drives are off. This pin
also features a precision threshold for power supply sequenc-
ing purposes, as well as a low threshold to ensure minimal
quiescent current.
HG (Pin 14) - High-gate drive pin. This is the gate drive for
the high-side N-channel MOSFET. This signal is interlocked
with LG (Pin 2) to avoid shoot-through.
20095202
MTC14
MTC14
2500 Units on Tape and Reel
94 Units, Raill
Supplied As
CC
to ensure