LM3670MF-1.875/NOPB National Semiconductor, LM3670MF-1.875/NOPB Datasheet - Page 13

• Manufacturer Part Number: LM3670MF-1.875/NOPB
• Description: IC CONV DC/DC STEP-DOWN SOT23-5
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Step-Down (Buck)r

Specifications of LM3670MF-1.875/NOPB

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.88V
• Current - Output: 350mA
• Frequency - Switching: 1MHz
• Voltage - Input: 2.5 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Other names: LM3670MF-1.875; LM3670MF-1.875TR

Application Information
noise filtering of the input voltage spikes due to this rapidly
changing current. Select an input filter capacitor with a surge
current rating sufficient for the power-up surge from the input
power source. The power-up surge current is approximately
the capacitor’s value (µF) times the voltage rise rate (V/µs).
The input current ripple can be calculated as:
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 func-
tions.
The output ripple current can be calculated as:
Voltage peak-to-peak ripple due to capacitance =
Voltage peak-to-peak ripple due to ESR =
VOUT (V)
10 µF for C
VJ1812V106MXJAT
4.7 µF for C
VJ1812V475MXJAT
C3216X5R0J475M
LMK432BJ106MM
EMK325BJ475MN
JMK325BJ106MM
0.7
0.8
0.9
1.0
IDC2512NB100M
CDRH5D18-100
DO1608C-103
ELL6RH100M
Model
Model
OUT
IN
R1 (KΩ)
80.6
120
160
200
TABLE 3. Adjustable LM3670 Configurations for Various V
TABLE 2. Suggested Capacitors and Their Suppliers
R2 (KΩ)
TABLE 1. Suggested Inductors and Their Suppliers
Ceramic
Ceramic
Ceramic
Ceramic
Ceramic
Ceramic
200
200
200
200
Type
(Continued)
Panasonic
Coilcraft
Vendor
Sumida
Vishay
C1 (pF)
200
130
100
82
Taiyo-Yuden
Taiyo-Yuden
Taiyo-Yuden
Vendor
Vishay
Vishay
TDK
13
Voltage peak-to-peak ripple, root mean squared =
Note that the output ripple is dependent on the current ripple
and the equivalent series resistance of the output capacitor
(R
Because these two components are out of phase the rms
value is used. The R
temperature dependent); make sure the frequency of the
R
frequency.
C2 (pF)
none
none
none
ESR
ESR
150
408-727-2500
847-639-6400
714-373-7366
847-956-0666
given is the same order of magnitude as the switching
).
Phone
408-727-2500
847-925-0888
847-925-0888
408-727-2500
847-925-0888
847-803-6100
L (µH)
4.7
4.7
4.7
4.7
Phone
ESR
is frequency dependent (as well as
OUT
CIN (µF)
4.7
4.7
4.7
4.7
408-330-4098
847-639-1469
714-373-7323
847-956-0702
408-330-4098
847-925-0899
847-925-0899
408-330-4098
847-925-0899
847-803-6296
FAX
FAX
COUT (µF)
www.national.com
10
10
10
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