LM3670MF-18 Datasheet, PDF (15/25 Pages) Texas Instruments – LM3670 Miniature Step-Down DC-DC Converter for Ultra Low Voltage Circuits

LM3670
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Model
IDC2512NB100M
DO1608C-103
ELL6RH100M
CDRH5D18-100
SNVS250E – NOVEMBER 2004 – REVISED FEBRUARY 2013
Table 1. Suggested Inductors and Their Suppliers
Vendor
Vishay
Coilcraft
Panasonic
Sumida
Phone
408-727-2500
847-639-6400
714-373-7366
847-956-0666
FAX
408-330-4098
847-639-1469
714-373-7323
847-956-0702
Output Capacitor Selection
The output filter capacitor smoothes out current flow from the inductor to the load, maintaining a steady output
voltage during transient load changes and reduces output voltage ripple. These capacitors must be selected with
sufficient capacitance and sufficiently low ESR to perform these functions.
The output ripple current can be calculated as:
Voltage
peak-to-peak
ripple
due
to
capacitance
=
V_PP-C
=
I_PP
f*8*C
Voltage peak-to-peak ripple due to ESR = ^VOUT ^{= VPP-ESR = IPP * RESR}
Voltage peak-to-peak ripple, root mean squared = ^{VPP-RMS = VPP-C2 + VPP-ESR2}
Note that the output ripple is dependent on the current ripple and the equivalent series resistance of the output
capacitor (R_ESR).
Because these two components are out of phase the rms value is used. The R_ESR is frequency dependent (as
well as temperature dependent); make sure the frequency of the R_ESR given is the same order of magnitude as
the switching frequency.
Model
10 µF for C_OUT
VJ1812V106MXJAT
LMK432BJ106MM
JMK325BJ106MM
4.7 µF for C_IN
VJ1812V475MXJAT
EMK325BJ475MN
C3216X5R0J475M
Table 2. Suggested Capacitors and Their Suppliers
Type
Vendor
Phone
Ceramic2
Ceramic
Ceramic
Vishay3
Taiyo-Yuden
Taiyo-Yuden
408-727-25004
847-925-0888
847-925-0888
Ceramic
Ceramic
Ceramic
Vishay
Taiyo-Yuden
TDK
408-727-2500
847-925-0888
847-803-6100
FAX
408-330-4098 5
847-925-0899
847-925-0899
408-330-4098
847-925-0899
847-803-6296
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