LM3409 Datasheet, PDF (2/30 Pages) National Semiconductor (TI) – PFET Buck Controller for High Power LED Drives

Connection Diagram
LM3409/09HV
30085602
10-Lead Exposed Pad eMSOP Package
Ordering Information
Order Number
LM3409MY
LM3409MYX
LM3409HVMY
LM3409HVMYX
NSC Package Drawing
MUC10A
MUC10A
MUC10A
MUC10A
Pin Descriptions
Top Marking
SXFB
SXFB
SYHB
SYHB
Supplied As
1000 Units on tape and reel
3500 Units on tape and reel
1000 Units on tape and reel
3500 Units on tape and reel
Pin(s)
1
Name
UVLO
2
IADJ
3
EN
4
COFF
5
GND
6
PGATE
7
CSN
8
CSP
9
VCC
10
DAP
VIN
DAP
Description
Input under-voltage lockout
Analog LED current adjust
Logic level enable /
PWM dimming
Off-time programming
Ground
Gate drive
Negative current sense
Positive current sense
V_IN- referenced
linear regulator output
Input voltage
Thermal pad on bottom of IC
Application Information
Connect to a resistor divider from V_IN and GND. Turn-on threshold is
1.24V and hysteresis for turn-off is provided by a 22µA current source.
Apply a voltage between 0 - 1.24V, connect a resistor to GND, or leave
open to set the current sense threshold voltage.
Apply a voltage >1.74V to enable device, a PWM signal to dim, or a
voltage <0.5V for low power shutdown.
Connect a resistor from V_O, and a capacitor from GND to set the off-
time.
Connect to the system ground.
Connect to the gate of the external PFET.
Connect to the negative side of the sense resistor.
Connect to the positive side of the sense resistor (also connected to
VIN).
Connect at least a 1µF ceramic capacitor to V_IN. The regulator provides
power for the PFET drive.
Connect to the input voltage.
Connect to pin 5 (GND). Place 4-6 vias from DAP to bottom layer GND
plane.
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