Datasheet
LM3431
www.ti.com
SNVS547G –NOVEMBER 2007–REVISED MAY 2013
PIN DESCRIPTIONS (continued)
Pin No. Pin Name Description
24 SNS1 Current feedback for channel 1.
25 NDRV1 Base drive for the channel 1 current regulator.
26 THM LED thermal monitor input pin. When pulled below 1.2V, device enters standby mode.
27 DIM PWM dimming input pin. Accepts a digital PWM or analog voltage level input to control LED current duty cycle.
28 EN Enable pin. Connect to VIN through a resistor divider to set an external UVLO threshold. Pull low to shutdown.
EP Exposed pad. Connect to SGND.
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.
ABSOLUTE MAXIMUM RATINGS
(1)
If Military/Aerospace specified devices are required, contact the Texas Instruments Semiconductor Sales Office/
Distributors for availability and specifications.
VALUE / UNIT
VIN –0.3V to 37V
EN –0.3V to 10V
DIM –0.3V to 7V
MODE/F –0.3V to 7V
REFIN –0.3V to 7V
THM –0.3V to 7V
DLY –0.3V to 7V
Voltages from the indicated pins to SGND:
SNSx –0.3V to 7V
NDRVx –0.3V to 7V
CFB –0.3V to 7V
SC -0.3V to 40V
AFB –0.3V to 7V
CS –0.3V to 7V
VCC –0.3V to 7V
Storage Temperature –65°C to +150°C
Infrared 20sec, 240°C
Soldering Dwell Time, Temperature
Vapor Phase 75sec, 219°C
ESD Rating Human Body Model
(2)
2 kV
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which
operation of the device is intended to be functional. For ensured specifications and test conditions, see the ELECTRICAL
CHARACTERISTICS.
(2) The human body model is a 100pF capacitor discharged through a 1.5 kΩ resistor into each pin.
RECOMMENDED OPERATING CONDITIONS
(1)
VALUE / UNIT
VIN 4.5V to 36V
Junction Temperature Range -40°C to +125°C
Thermal Resistance (θ
JA
)
(2)
, TSSOP-28 (0.5W) 32°C/W
Power Dissipation
(3)
, TSSOP-28 3.1W
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which
operation of the device is intended to be functional. For specifications and test conditions, see the ELECTRICAL CHARACTERISTICS.
(2) The Thermal Resistance specifications are based on a JEDEC standard 4-layer pcb. θ
JA
will vary with board size and copper area.
(3) The maximum allowable power dissipation is a function of the maximum junction temperature, T
J_MAX
, the junction-to-ambient thermal
resistance, θ
JA
, and the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient temperature is calculated
using: P
D_MAX
= (T
J_MAX
– T
A
)/θ
JA
. The maximum power dissipation is determined using T
A
= 25°C, and T
J_MAX
= 125°C.
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