LM3671MF-1.5EV National Semiconductor, LM3671MF-1.5EV Datasheet - Page 2

• Manufacturer Part Number: LM3671MF-1.5EV
• Description: BOARD EVALUATION LM3671MF-1.5
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3671MF-1.5EV

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.5V
• Current - Output: 600mA
• Voltage - Input: 2.7 ~ 5.5V
• Regulator Topology: Buck
• Frequency - Switching: 2MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM3671
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Power - Output: -

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Output Voltage Selection for
LM3671MF-ADJ
The output voltage of the adjustable parts can be pro-
grammed through the resistor network connected from V
to FB to GND. The resistor from FB to GND (R
200 kΩ to keep the current drawn through this network well
below 16 µA quiescent current level (PFM mode) but large
enough that it is not susceptible to noise. If R
the V
network will be 2.5 µA. The output voltage of the adjustable
parts ranges from 1.1V to 3.3V. The output voltage formula
is:
V
OUT
V
: output voltage (V)
1.875
FB
OUT
1.1
1.2
1.3
1.5
1.6
1.7
1.8
2.5
2.8
3.3
is 0.5V, then the current through the resistor feedback
(V)
R
1
240
280
320
357
442
432
464
523
402
464
562
(kΩ )
TABLE 1. LM3671-ADJ Configurations for Various V
R
2
200
200
200
178
200
178
178
191
100
100
100
(kΩ )
2
is 200 kΩ, given
C
2
) should be
1
8.2
8.2
8.2
6.8
8.2
8.2
6.8
15
12
12
10
(pF)
OUT
C
none
none
none
none
none
none
none
none
none
2
2
33
33
(pF)
V
R
R
For the fixed output voltage parts the feedback resistors are
internal and R
The bypass capacitors C
uation Board) in parallel with the feedback resistors are cho-
sen for increased stability. Below are the formulas for C
C
FB
1
2
2
: feedback resistor from V
: feedback resistor from FB to GND (Ω)
.
: feedback voltage (0.5V typical)
L (µH)
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
out
1
(Circuit of Figure 2)
is 0Ω.
C
1
IN
and C
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
4.7
(µF)
OUT
2
to FB (Ω )
(labeled C
C
3
OUT
and C
10
10
10
10
10
10
10
10
10
10
10
(µF)
4
on Eval-
1
and