LM3434QX/NOPB National Semiconductor, LM3434QX/NOPB Datasheet - Page 10

• Manufacturer Part Number: LM3434QX/NOPB
• Description: IC LED DRIVER DIMM 24-LLP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: High Power, Constant Currentr

Specifications of LM3434QX/NOPB

• Constant Current: Yes
• Topology: PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: Automotive
• Type - Secondary: High Brightness LED (HBLED)
• Frequency: 1MHz
• Voltage - Supply: 3 V ~ 5.8 V
• Mounting Type: Surface Mount
• Package / Case: 24-LLP
• Operating Temperature: -40°C ~ 125°C
• Internal Switch(s): No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Current - Output / Channel: -
• Efficiency: -
• Other names: LM3434QX

LAYOUT CONSIDERATIONS
The LM3434 is a high performance current driver so attention
to layout details is critical to obtain maximum performance.
The most important PCB board design consideration is mini-
mizing the loop comprised by the main FET, synchronous
FET, and their associated decoupling capacitor(s). Place the
V
bypass capacitor as near as possible to the LM3434.
CC
Place the PWM dimming/shunt FET as close to the LED as
possible. A ground plane should be used for power distribu-
tion to the power FETs. Use a star ground between the
LM3434 circuitry, the synchronous FET, and the decoupling
capacitor(s). The EP contact on the underside of the package
must be connected to V
. The two lines connecting the sense
EE
resistor to CSN and CSP must be routed as a differential pair
directly from the resistor. A Kelvin connection is recommend-
ed. It is good practice to route the DIMO/DIMR, HS/HO, and
LO/LS lines as differential pairs. The most important PCB
board design consideration is minimizing the loop comprised
by the main FET, synchronous FET, and their associated de-
coupling capacitor(s). Optimally this loop should be orthogo-
nal to the ground plane.
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