LM2670S-ADJ National Semiconductor, LM2670S-ADJ Datasheet - Page 9
![DC/DC Converter IC](/photos/19/2/190204/4243352_sml.jpg)
LM2670S-ADJ
Manufacturer Part Number
LM2670S-ADJ
Description
DC/DC Converter IC
Manufacturer
National Semiconductor
Specifications of LM2670S-ADJ
Input Voltage
40V
Output Voltage
37V
No. Of Pins
5
Termination Type
SMD
Mounting Type
Through Hole
Voltage Regulator Type
Buck Switching
Output Current Max
3A
Peak Reflow Compatible (260 C)
No
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LM2670S-ADJ
Manufacturer:
NS
Quantity:
4 000
Part Number:
LM2670S-ADJ
Manufacturer:
NS/国半
Quantity:
20 000
Application Hints
DESIGN CONSIDERATIONS
Power supply design using the LM2670 is greatly simplified
by using recommended external components. A wide range
of inductors, capacitors and Schottky diodes from several
manufacturers have been evaluated for use in designs that
cover the full range of capabilities (input voltage, output volt-
age and load current) of the LM2670. A simple design proce-
dure using nomographs and component tables provided in
this data sheet leads to a working design with very little ef-
fort. Alternatively, the design software, LM267X Made
Simple (version 2.0), can also be used to provide instant
component selection, circuit performance calculations for
evaluation, a bill of materials component list and a circuit
schematic.
The individual components from the various manufacturers
called out for use are still just a small sample of the vast ar-
ray of components available in the industry. While these
components are recommended, they are not exclusively the
only components for use in a design. After a close compari-
son of component specifications, equivalent devices from
other manufacturers could be substituted for use in an appli-
cation.
FIGURE 2. Basic circuit for adjustable output voltage applications
(Continued)
FIGURE 1. Basic circuit for fixed output voltage applications.
9
Important considerations for each external component and
an explanation of how the nomographs and selection tables
were developed follows.
INDUCTOR
The inductor is the key component in a switching regulator.
For efficiency the inductor stores energy during the switch
ON time and then transfers energy to the load while the
switch is OFF.
Nomographs are used to select the inductance value re-
quired for a given set of operating conditions. The nomo-
graphs assume that the circuit is operating in continuous
mode (the current flowing through the inductor never falls to
zero). The magnitude of inductance is selected to maintain a
maximum ripple current of 30% of the maximum load cur-
rent. If the ripple current exceeds this 30% limit the next
larger value is selected.
The inductors offered have been specifically manufactured
to provide proper operation under all operating conditions of
input and output voltage and load current. Several part types
are offered for a given amount of inductance. Both surface
DS100942-7
DS100942-8
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