LM3407EVAL National Semiconductor, LM3407EVAL Datasheet - Page 13

• Manufacturer Part Number: LM3407EVAL
• Description: BOARD EVALUATION FOR LM3407
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3407EVAL

• Current - Output / Channel: 350mA
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 4.5V
• Features: Dimmable
• Voltage - Input: 4.5 ~ 30V
• Utilized Ic / Part: LM3407
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

PRINTED CIRCUIT BOARD DESIGN
Since the copper traces of PCBs carry resistance and para-
sitic inductance, the longer the copper trace, the higher the
resistance and inductance. These factors introduce voltage
and current spikes to the switching nodes and may impair cir-
cuit performance. To optimize the performance of the
LM3407, the rule of thumb is to keep the connections between
components as short and direct as possible. Since true aver-
age current regulation is achieved by detecting the average
switch current, the current setting resistor R
cated as close as possible to the LM3407 to reduce the
parasitic inductance of the copper trace and avoid noise pick-
up. The connections between the LX pin, rectifier D1, inductor
FIGURE 7. Typical Application Schematic for 6 LEDs
FIGURE 8. Typical Application Schematic for 1 LED
ISNS
must be lo-
13
L1, and output capacitor C
possible to reduce the voltage spikes at the LX pin. It is rec-
ommended that C
nal linear regulator of the LM3407, be placed close to the VCC
pin. The input filter capacitor C
L1 and the cathode of D1. If C
by a long trace, a 0.1µF capacitor should be added close to
VIN pin for noise filtering. In normal operation, heat will be
generated inside the LM3407 and may damage the device if
no thermal management is applied. For more details on
switching power supply layout considerations see Application
Note AN-1149: Layout Guidelines for Switching Power Sup-
plies.
VCC
, the output filter capacitor for the inter-
OUT
IN
IN
should be kept as short as
is connected to the VIN pin
should be located close to
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