LM2671M-3.3/NOPB National Semiconductor, LM2671M-3.3/NOPB Datasheet - Page 20

• Manufacturer Part Number: LM2671M-3.3/NOPB
• Description: IC REG SIMPLE SWITCHER 8-SOIC
• Manufacturer: National Semiconductor
• Series: SIMPLE SWITCHER®r
• Type: Step-Down (Buck)r

Specifications of LM2671M-3.3/NOPB

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 3.3V
• Current - Output: 500mA
• Frequency - Switching: 260kHz
• Voltage - Input: 6.5 ~ 40 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Primary Input Voltage: 12V
• No. Of Outputs: 1
• Output Voltage: 3.3V
• Output Current: 500mA
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +125°C
• Msl: MSL 1 - Unlimited
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Other names: *LM2671M-3.3; *LM2671M-3.3/NOPB; LM2671M-3.3

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Application Information
TYPICAL SURFACE MOUNT PC BOARD LAYOUT, FIXED
OUTPUT (4X SIZE)
C
C
D1 - 1A, 40V Schottky Rectifier, Surface Mount
L1 - 47 μH, L13, Coilcraft DO3308
C
TYPICAL SURFACE MOUNT PC BOARD LAYOUT,
ADJUSTABLE OUTPUT (4X SIZE)
C
C
D1 - 1A, 40V Schottky Rectifier, Surface Mount
L1 - 100 μH, L20, Coilcraft DO3316
C
R1 - 1k, 1%
R2 - Use formula in Design Procedure
Layout is very important in switching regulator designs.
Rapidly switching currents associated with wiring inductance
can generate voltage transients which can cause problems.
For minimal inductance and ground loops, the wires indicated
by heavy lines (in Figure 2 and Figure 3) should be wide
printed circuit traces and should be kept as short as pos-
sible. For best results, external components should be locat-
ed as close to the switcher IC as possible using ground plane
construction or single point grounding.
IN
OUT
B
IN
OUT
B
- 0.01 μF, 50V, Ceramic
- 0.01 μF, 50V, Ceramic
- 15 μF, 25V, Solid Tantalum Sprague, “594D series”
- 15 μF, 50V, Solid Tantalum Sprague, “594D series”
- 68 μF, 10V, Solid Tantalum Sprague, “594D series”
- 33 μF, 25V, Solid Tantalum Sprague, “594D series”
FIGURE 18. PC Board Layout
20
If open core inductors are used, special care must be taken
as to the location and positioning of this type of inductor. Al-
lowing the inductor flux to intersect sensitive feedback, IC
ground path, and C
When using the adjustable version, special care must be tak-
en as to the location of the feedback resistors and the asso-
ciated wiring. Physically locate both resistors near the IC, and
route the wiring away from the inductor, especially an open
core type of inductor.
OUT
wiring can cause problems.
10004239
10004240