LM3406HVMHX/NOPB National Semiconductor, LM3406HVMHX/NOPB Datasheet - Page 25

• Manufacturer Part Number: LM3406HVMHX/NOPB
• Description: IC LED DRVR HP CONS CURR 14TSSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: High Power, Constant Currentr

Specifications of LM3406HVMHX/NOPB

• Constant Current: Yes
• Topology: PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Automotive
• Type - Secondary: White LED
• Frequency: 1MHz
• Voltage - Supply: 6 V ~ 75 V
• Mounting Type: Surface Mount
• Package / Case: 14-TSSOP Exposed Pad, 14-eTSSOP 14-HTSSOP
• Operating Temperature: -40°C ~ 125°C
• Current - Output / Channel: 1.5A
• Internal Switch(s): Yes
• Efficiency: 96%
• For Use With: 876-1003 - LM3406 LED DRIVER EVAL BOARDLM3406MHEVAL - BOARD EVAL FOR LM3406MH
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Other names: LM3406HVMHX

switching of output current by the parallel FET produces a
pulsating current just like the switching action of the LM3406's
internal power FET and the Schottky diode.
Figure 18
shows
the path that the inductor current takes through the LED or
through the dimming FET. To minimize the EMI from parallel
FET dimming the parasitic inductance of the loop formed by
the LED and the dimming FET (where only the dark grey ar-
rows appear) should be reduced as much as possible. Para-
sitic inductance of a loop is mostly controlled by the loop area,
hence making this loop as physically small (short) as possible
will reduce the inductance.
30020328
FIGURE 18. Parallel FET Dimming Current Loops
www.national.com
24