LM3679TL-1.8EV National Semiconductor, LM3679TL-1.8EV Datasheet - Page 11

• Manufacturer Part Number: LM3679TL-1.8EV
• Description: BOARD EVALUATION LM3679TL-1.8
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3679TL-1.8EV

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.8V
• Current - Output: 350mA
• Voltage - Input: 2.5 ~ 5.5V
• Regulator Topology: Buck
• Frequency - Switching: 3MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM3679
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

4.7 µF for C
10 µF for C
GRM185R60J475M(0.5mm height) **
GRM185R60J475M (0.5mm height) *
JMK107BJ475MK (0.5mm Height) *
JMK107BJ475MK(0.5mm height) **
Note : *For Low Profile Solution
OUTPUT CAPACITOR SELECTION
A ceramic output capacitor of 10 µF, 6.3V is sufficient for most
applications. Use X7R or X5R types; do not use Y5V. DC bias
characteristics of ceramic capacitors must be considered
when selecting case sizes like 0603 and 0805. DC bias char-
acteristics vary from manufacturer to manufacturer and dc
bias curves should be requested from them as part of the ca-
pacitor selection process.
The minimum output capacitance to guarantee good per-
formance is 5.75µF at 2.5V dc bias including tolerances
and over ambient temperature range. The output filter ca-
pacitor smoothes out current flow from the inductor to the
load, helps maintain a steady output voltage during transient
load changes and reduces output voltage ripple. These ca-
pacitors must be selected with sufficient capacitance and
sufficiently low ESR to perform these functions.
The output voltage ripple is caused by the charging and dis-
charging of the output capacitor and by the R
calculated as:
Voltage peak-to-peak ripple due to capacitance can be ex-
pressed as follows
Note: * For Low Profile Solution
MIPSA2520D 1R0
LQM21PN1R0M *
BRL2518T1R0M
LQM2HP 1R0
GRM21BR60J475
GRM21BR60J106
C1608X5R0J475
C2012X5R0J475
C1608X5R0J106
C2012X5R0J106
OUT
IN
JMK212BJ475
JMK212BJ106
Model
Model
TABLE 2. Suggested Capacitors and Their Suppliers
TABLE 1. Suggested Inductors and Their Suppliers
Taiyo Yuden
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Ceramic, X5R
Vendor
Murata
Murata
FDK
Type
ESR
and can be
Taiyo-Yuden
Taiyo-Yuden
Taiyo-Yuden
Taiyo-Yuden
muRata
muRata
muRata
muRata
Vendor
11
TDK
TDK
TDK
TDK
Voltage peak-to-peak ripple due to ESR can be expressed as
follows
V
Because these two components are out of phase the rms (root
mean squared) value can be used to get an approximate val-
ue of peak-to-peak ripple.
Voltage peak-to-peak ripple, rms can be expressed as follow:
Note that the output voltage ripple is dependent on the induc-
tor current ripple and the equivalent series resistance of the
output capacitor (R
The R
dependent); make sure the value used for calculations is at
the switching frequency of the part.
Note: ** For Low Profile solution use two 4.7uF in parallel for
C
Dimensions LxWxH(mm)
PP-ESR
OUT
.
2.5 x 2.0 x 0.95
2.0 x1.25 x 0.5
2.5 x 2.0 x 1.2
ESR
2.5x 1.8 x 1.2
= (2 * I
is frequency dependent (as well as temperature
Voltage Rating
RIPPLE
6.3V
6.3V
6.3V
6.3V
6.3V
6.3V
6.3V
6.3V
6.3V
6.3V
6.3V
6.3V
ESR
) * R
).
ESR
0603 (1608) X 2 **
0603 (1608) X 2 **
0603 (1608) *
0603 (1608) *
0603 (1608)
0805 (2012)
0805 (2012)
0805 (2012)
0603 (1608)
0805 (2012)
0805 (2012)
0805 (2012)
Inch (mm)
Case Size
D.C.R (max)
100 mΩ
100 mΩ
190mΩ
80 mΩ
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