DC-DC converter, switching regulator

using LM2576, LM2575, LM2575, LM2576, LM2596, LM2678, LM22678, LM22675, and more.

Written by Lim Siong Boon, last dated 08-Dec-09.

email:    contact->email_siongboon  

website: http://www.siongboon.com


 

Kit Research History

 

LM7805, TO220 package

 

 

 

 

 

SD-50A-5

  SDM-30

PMA8811SF

UT70A

 

 

 

Various type of voltage regulator design

 

a) Zener diode voltage regulator.

Suitable only for very low power application.

 

For Vcc 24V
- Zener (Vout) = 12V 240mW, Iout(max) = 20mA, Rreg = 600ohm 240mW

- Zener (Vout) = 12V 120mW, Iout(max) = 10mA, Rreg = 1200ohm 120mW
- Zener (Vout) = 5V 100mW, Iout(max) = 20mA, Rreg = 950ohm 380mW

For Vcc 12V
- Zener (Vout) = 5V 100mW, Iout(max) = 20mA, Rreg = 350ohm 140mW

- Zener (Vout) = 3.3V 66mW, Iout(max) = 20mA, Rreg = 435ohm 174mW

Refer to the following website to compute zener, resistor value for a required Vout/Iout.
http://www.reuk.co.uk/Zener-Diode-Voltage-Regulator.htm

 

b) 3 rectifier diodes as voltage regulator.

Suitable only for very low power application.

 

c) Using voltage reference TL431 as a voltage regulator.

This is a very simple and useful adjustable voltage regulator. If the load is <100mA, this is a very attractive solution. For 5V output, R1=R2=10Kohm. TL431 datasheet.

LT431 voltage reference as regulator

 

d) Linear voltage regulator.

Suitable for application that requires low noise.

 

e) Switching voltage regulator.

Suitable for application that requires high power.

 

Circuit diagram taken from,

Power Supply Design for electronic circuit

A dc-dc regulator/converter or another name known as buck regulator or switching regulator, provides stable regulated output voltage to supply electronic circuits. Schematic, PCB layout and component list are available on this page.

LM2576 circuits perform same function as the commonly known voltage regulator LM7805 from National Semiconductor. The 7805 voltage regulator dissipates a lot heat. The higher input voltage, the more heat is generated. The extra input energy is converted to heat, keeping the output voltage regulated at 5V.

LM78XX series is available to regulate 5, 6, 8, 9, 12, 15, 18, 24V. If you want the output voltage adjustable, there is also a adj model. For -negative voltage supply, you can use LM79xx series. These regulator is able to support up to a maximum of 1A current rating.

LM7805 IC requires input voltage to be higher than output in order to regulate the output voltage. Input voltage needs to be at least 7V (up to a maximum of 20V) in order for LM7805 to regulate at an output of 5V. It is advisable to supply a voltage input range from 7.5V to 10V. Any higher input voltage is consider inefficiency, generating a lot of  heat.

A switching mode power supply such as LM2576 dc-dc converter, uses switching control to reduce the input dc voltage on average. This is equivalent to a lower input voltage resulting in minimum heat dissipated. The control results in better regulated output, less energy wasted through heat and the use for high current application. Nowadays dc-dc converter are getting smaller and comes in the TO-220 package too. You can simply change your LM7805 to dc-dc converter without any change in your design.

The first commerical module I tried is the SD-50A-5 from Meanwell rated at 5V 10A. It is very good and easy to use. However it is very big and bulky. If size is a constraint, you might consider the model SDM-30. It is able to handle up to 5V 5A and is a lot smaller than SD-50A-5. However it generates a lot of heat through its metal casing.

The best dc-dc I have tried before is PMA8811SF from Ericsson. It is by far the most compact (smaller than SDM-30) and most efficient dc-dc. Heat is also dissipated through it ceramic package, however it does not scalded your finger as much as SDM-30 do.  The IC package is surface mount however soldering is relatively easy because the IC leads are quite broad. It is rated at output 5Vdc 16A and generate far less heat. Each pieces cost about S$60, a lot more than the other converter model.

Through some research, I get to learn about commercial standard dc-dc IC that perform with only a few external components. The following article discuss on LM2576 IC with rating up to 5V 3A. LM2576 is one of the dc-dc IC product range from National Semiconductor. There are also various brand of dc-dc regulator IC available.

The interfacing of most dc-dc IC requires the use of inductor. This is the case for LM2576 too. Try sourcing your local electronics shop for one if possible. I am not stopping you to make your own inductor. Just that making your own inductor takes up time and it is very likely to cost you more than what a shop might be selling.

If you are interested in making your own coil, you might interested in this website, http://www.skylab.org/~chugga/mpegbox/coil/. The aurthor Jeff Mucha had demonstrated a simple and creative way to make inductive. One Long screw, 2 board flat washer, 2 nut, 1 ring spacer, glue, and XXX is all the tools that is require to make your own air core inductor. It is really interesting.

More article: home brew your own inductors

Jens Moller has contributed a program which generate a table of information for building air core inductor. Simply input the inductance value you need, the program will display a table containing the wire coil height radius and number of turns required. You need not have to understand formula to make your own inductor. Take a look at the following website, http://www.colomar.com/Shavano/inductor_info.html

A greenhorn when I first attempt to use inductor. It is a tough job building circuits using inductor. I do not have proper equipment to measure the inductor on hand. Never able to find out the inductance value I have. Fortunately, there is this inductance measurement product selling at an affordable price. UT70A from Uni-Trend Technology. It also function as a multi-meter, and can be used to measure voltage, current, etc... . Even with an inductance meter, it is not a easy task to measure inductance accurately.

 

 

 

 

 

Other reference:

The practical basic of building a power supply.

- The Power Supply.pdf

http://www.talkingelectronics.com/

projects/ThePowerSupply/Page79PowerSupplyP1.html

 

 

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2009-09-13 dc-dc step up, LED driver using 1.5V alkaline battery

The simplest DC-DC step up converter I have done. Typical LED requires about 2V to operate. This ciruict is able to drive the LED from a 1.5V battery. The transistor forms the oscillating circuit generating pulsing output. Although the output is pulsing, we can't actually see it on the LED, as the switching is quite fast.

Click the picture to enlarge.

 

The voltage output is about 3Vpeak oscillating at about 33kHz.

 

 

 

 

 

 

Schematic

 

   

 

 

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LM2576 dc-dc Circuits

 

Photos of DC-DC circuit built

 

 

This is the 1st successful DC-DC circuit I built.

There a variety of capacitors out there in the market. Capacitance, voltage rating, dielectric material, etc... . Choose a suitable voltage rating across the capacitor. The circuits deals with high current, therefore it will be better to choose a low ESR (equivalent series resistance) Aluminum electrolytic capacitor. As a general guide, a higher voltage rating has lower ESR rating.

The inductor coil use should be able to handle the current passing through the inductor coil. If the wire is too thin, the coil may be burn or just fail. My previous circuit uses small wattage inductor (package like a big resistor). The circuit couldn't work and was later found to be IC problem. I have not yet do a test to check on the possibility of the inductor contributing to the failure.

Using a inductor meter to measure the inductance will be easier. Inductance value can be observe immediately for any modification to the coil of wire. The inductance value can also be calculated, depend on the coil size, number of turns, wire size used, dielectric of the core etc... .

The 1N5822 is a high current, high speed, schottky diode and is suitable for this digital switching circuit. Schottky diode (Schottky Barrier Rectifier), means that the forward voltage drop is low. For this application, a low forward voltage diode is necessary.

 

 

   
 

 

Schematics

   

PCB Bottom Layer (PCB trace)

Component Layout (Silkscreen)

   

Bill of Material (BOM) for LM2576 circuit

Part# Description Value Qty
C1 Electrolytic Capacitor (Axial) 100uF 75V x1
C2 Aluminum Electrolytic Capacitors (Axial) 1000uF 16V x1
D1 Schottky Diode (high current) 1N5822 x1
L1 Inductor 100uH x1
U1 7-40V to 5V DC-DC 3.0A LM2576T5 x1
R1 Resistor 1K x1
DS1 Typical INFRARED GaAs LED   x1
JP1 Header, 2-Pin   x1
JP2 Header, 2-Pin   x1
PCB PCB board 60x50mm 1 oz x1

 

 

LM2576 circuits that failed  
 

Failure, my first prototype circuit to test out the performance of LM2575, LM2576.

 

 

 

Some of the various sizes of inductor tested and seems to be working with LM2576.

 

Initially I thought that I had use the wrong type of inductor, resulting in the circuit malfunction. Initially I had used a smaller type of inductor (looks like a resistor). Realizing that this circuit drive high current load, I should use a thicker inductor coil. That's why I modified the circuit with an inductor (enamelled wire, wound around the ferrite core).

Still it doesn't work. I guess that both IC LM2575, LM2576 must have been damage by my previous attempt. The capacitor used is suspected because the datasheet call for low ESR capacitor. It is very difficult to find these in the local shops, therefore I use a normal capacitor instead.

One day, I visited a shop selling ready made inductors and brought LM2576 at the same time. The circuit was rebuild and it finally works. My deduction at that time was either the inductor or the capacitor is giving me the problem. After further testing, I find out that ordinary capacitor works as well. There is hardly any difference in performance. Various type of inductor were tested (except the resistor like type). All inductor works too, big or small. Quite weird actually, and I couldn't figure it out the actual problem I had in my previous attempt.

The mystery is resolve finally. One fine day I went back to the shop where I first purchase my LM2576 and brought 2 additional LM2576 for more testing. A new circuit was build and the familiar failure was observed. The output voltage of 5V cannot be sustain and eventually drop when more than 1A of current is draw by the load. The lab power supply display a current loading limit warning. IC becomes very hot. The datasheet specify that LM2576 should be able to supply 3A without any  problem. Both brand new IC are tested to have the same problem.

This is weird, as the same inductor and capacitor previously tested do not result in this same old problem. However the circuit shows the same failure symptom. The next thing that comes to mind, is the IC. The IC LM2576 from the previous working circuit is then transfer over the new circuit board for testing. Everything works fine. It is then clear that the problem comes from the IC itself.

Checking up on the previous IC, I notice that they are from the same manufacturing batch number and believe that they are already damage in some way.

 

Sample of the 5Ω 50W aluminum house resistor used for testing 1A current performance.

Using various type of inductor and capacitor. The circuit is tested to draw 1A using a 5Ω 50W resistor as the load. Current drawn can be observe on my lab power supply current meter. It should shows 1A being drawn, since the LM2576 supply a constant 5V to the 5Ω load.

 

General tester for LM series dc-dc IC chip.

A multi purpose board is created to allow me to test various LM series IC chip. e.g. LM2575, LM2576, LM2596, LM2678, LM2679. Various combination of inductor, capacitor and diode can also be tested under this board.

 

More LM2576 Circuits built  

 

 

 

Some of the newly fabricated board built to support other prototype projects. It has been tested to support a RF transceiver operating at 5V without any issue observed.

 

 

 

 

   

 

This is the same dc-dc circuit shown above. The circuit is fabricated from photo-resist PCB board. For more information on making your own PCB board, you may like to visit, website "..\2005-09-07_home_pcb_fabrication".

Home fabricated circuit board

 

Working on LM2575

 

 

It has been some time since I learn to use LM2576. The circuitry is able to handle a higher current at 3A 5V output. This translate to a higher cost and circuit size, since all component must be able to handle that high power capacity. These component include the LM2576, inductor and the diode. Since most electronics kit requires less than 1A power supply, it is wise learning how to apply a low power dc-dc regulator like LM2575. Cost can be reduce by 50%.

There is one day that I happen to come across this IC LM2575 while searching high and low for LM2576. LM2576 is actually quite difficult to find. There is only 2 shop I know of, but I have rule out one shop because they are selling a faulty batch of LM2576 IC. LM2575 seems very common from shops around and I decided to find out more about this chip. Indeed it is what I have been looking for, a low power regulator. So I purchase the IC and its component to try it out. When I started writing this acticle, only did I realize that I have actually tried it about 6 months ago. The experiment was forgotten after a series of failure.

But now, it is working once more. The experience in working with LM2576 has provided the confident to built LM2575. It is so fortunate that I managed to get this circuit working once again.

The following experiment is done during the 1st test on LM2575 circuit. The experiment compare between the performance of using different inductor. One using a wire coil inductor, and the other smaller one inductor that looks like a resistor with it's color bands..

The photos on the left column shows the LM2575 circuit using the correct inductance value at 330uH but the inductor is low power rated. It is small and looks like a color coded resistor.

A few second after the left circuit is powered up, the small inductor turns very hot. The waveform observed at the output of the dc-dc regulator, contains a high amount of noise/ripple energy.

The photo on the right column shows the same circuit using a slightly higher inductance at 480uH but the coil is thicker and bigger in size.

The circuit using a high power rating inductor on the right shows a cleaner DC supply, although the inductance value is different from the design. There is still ripple at it's output but I guess it will be minimum using an inductance value of 330uH with higher power rating. Too bad, I do not have the right inductor to experiment further. It is either coil one myself or buy one from shop.

12 June 2006, Lim Siong Boon

 

I have found this article regarding about the property of inductor Isat (current saturation) and Irms (continuous current). They are usually one of the important specification to take note while selecting inductor from datasheet.

Current saturation means the amount of current required that flow through the inductor, in order to reduce the inductance of the component.

Continuous current means the amount of current required to heat up the inductor to a certain temperature. If the amount current continue to flow through the inductor, the inductor is basically becoming a heater. The temperature depends on the amount of current flowing through it.

The following contains information that I learn from.

Isat_Irms explain.pdf

02 Dec 2008, Lim Siong Boon

 

 

LM2575 Schematic taken from National Semiconductor LM2575 datasheet

 

Bill of Material (BOM) for LM2575 circuit

Part# Description Value Qty
C1 Electrolytic Capacitor (Axial) 100uF 75V x1
C2 Aluminum Electrolytic Capacitors (Axial) 330uF 16V x1
D1 Schottky Diode (low current) 1N5819 x1
L1 Inductor 330uH x1
U1 7-40V to 5V DC-DC 1.0A LM2575T5 x1
R1 Resistor 1K x1
DS1 Typical INFRARED GaAs LED   x1
JP1 Header, 2-Pin   x1
JP2 Header, 2-Pin   x1
PCB PCB board 60x50mm 1 oz x1

 

click here to
Buy DC-DC Converter
Available Now at the PIC-store

 

 

 

 

 

Dealing with power supply noise

I happen to see this very good website, teaching about handling noise. There are many illustration which are easy to understand.

http://www.williamson-labs.com/480_byp.htm

 

04 Oct 2011, Lim Siong Boon

   

 

 

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Quick Design Guide to

Switching Power IC

 

LM2575, LM2576, LM2596, LM2678

 

The following table provides a quick reference for power supply circuit. The circuit schematic and component list are selected from the manufacturer's datasheet.

For exact component value design, you need to the datasheet. The following component value is design for typical input voltage of 12Vdc or 24Vdc drawing power at 75% of the current rating.

 

   

LM2575 (1A)

DC to DC step down voltage regulator.

Wide input voltage 8Vdc to 40Vdc.

 

 

Part number:

- LM2575-3.3 (3.3Vdc output)

- LM2575-5.0 (5Vdc output)

- LM2575-12 (12Vdc output)

- LM2575-15 (15Vdc output)

- LM2575-ADJ (1.23Vdc to 37Vdc output)



Alternative:

NJM2367

 

 

Package: TO-220(T)

 

 

click here to
Buy DC-DC Converter Available Now at the PIC-store

 

 

 

LM2575 datasheet

Click for LM2575-adj circuit

Component list

Symbol

Component  

C1

100uF (50V aluminium electrolytic)  

C2

330uF (16V aluminium electrolytic, low ESR)  
D1 1N5819 (schottky diode 1A)  
L1

330uH, 1A  <for LM2575-3.3, LM2575-5.0>

680uH, 1A  <for LM2575-12, LM2575-15>

 
R1, R2 "for LM2575-adj IC" 5kΩ multi-turn variable resistor, set to ratio to R1=1.25kΩ, R2=3.75kΩ for voltage output of 5Vdc before soldering.  

 

For 3.3V output

 

Commercial Resistor value

Actual Output

R1

R2

 

R1

R2

Vout

1.00kΩ

1.68kΩ

 

1.0kΩ

 

 

3.30kΩ

5.55kΩ

 

3.3kΩ

(3.24kΩ)

5.6kΩ

(5.49kΩ)

3.32V

4.70kΩ

7.91kΩ

 

4.7kΩ

 

 

1.96kΩ

3.30kΩ

 

 

3.3kΩ

 

2.79kΩ

4.70kΩ

 

 

4.7kΩ

 

3.33kΩ

5.60kΩ

 

3.3kΩ

(3.24kΩ)

5.6kΩ

(5.49kΩ)

3.32V

 

 

For 5.0V output

 

Commercial Resistor value

Actual Output

R1

R2

 

R1

R2

Vout

1.00kΩ

3.07kΩ

 

1.0kΩ

 

 

3.30kΩ

10.10kΩ

 

3.3kΩ

(3.24kΩ)

10.0kΩ

(10.00kΩ)

4.96V

4.70kΩ

14.40kΩ

 

4.7kΩ

 

 

1.08kΩ

3.30kΩ

 

 

3.3kΩ

 

1.53kΩ

4.70kΩ

 

 

4.7kΩ

 

1.83kΩ

5.60kΩ

 

 

5.6kΩ

 

3.26kΩ

10.00kΩ

 

3.3kΩ

(3.24kΩ)

10.0kΩ

(10.00kΩ)

4.96V

 

 

please refer to the table for resistors in parallel for more resistance design options.

 

 

Other voltage output base on commercial available resistors

 

Commercial Resistor value

Actual Output

   

 

R1

R2

Vout

   

 

1.0kΩ

4.7kΩ

7.011V

   

 

1.18kΩ

18kΩ

19.9927V

   

 

   

 

   

 

   

 

   

 

   

 

   

 

     
   

 

     

 

 

    Vout, R1 & R2 design selection calculator

    Vout=, R1=, R2=          where R1 between 1kΩ to 5kΩ.

    Design calculator might not work on some web browser.

 

   

LM2825 (1A)

DC to DC step down voltage regulator.

Wide input voltage up to 40Vdc.

 

 

Part number:

- LM2825-3.3 (3.3Vdc output)

- LM2825-5.0 (5Vdc output)

- LM2825-12 (12Vdc output)

- LM2825-ADJ (1.23Vdc to 37Vdc output)

 

 

Package: MDIP24

LM2825 datasheet

 

no external component required

   

LM2576 (3A)

DC to DC step down voltage regulator.

Wide input voltage 8Vdc to 40Vdc.

 

 

Part number:

- LM2576-3.3 (3.3Vdc output)

- LM2576-5.0 (5Vdc output)

- LM2576-12 (12Vdc output)

- LM2576-15 (15Vdc output)

- LM2576-ADJ (1.23Vdc to 37Vdc output)



Alternative:

NJM2367

 

 

Package: TO-220(T)

 

tested working on 2007-06-26

tested working on 2007-06-26

LM2576 datasheet

Click for LM2576-5.0 layout

 

Click for LM2576-adj circuit

Click for LM2576-adj layout

Reference:

- AN-946, lm2576 as a charger

 

Component list

Symbol

Component  

C1

100uF (50V aluminium electrolytic)  

C2

1000uF (16V aluminium electrolytic, low ESR)  
D1 1N5822 (schottky diode 3A)  
L1

100uH, 3A  <for LM2576-3.3, LM2576-5.0>

220uH, 3A  <for LM2576-12, LM2576-15>

 
R1, R2 "for LM2576-adj IC" 5kΩ multi-turn variable resistor, set to ratio to R1=1.25kΩ, R2=3.75kΩ for voltage output of 5Vdc before soldering.  

 

Resistor value for Adj (adjustable version). Voltage reference is 1.23V

For 3.3V output

 

Commercial Resistor value

Actual Output

R1

R2

 

R1

R2

Vout

1.00kΩ

1.68kΩ

 

1.0kΩ

 

 

3.30kΩ

5.55kΩ

 

3.3kΩ

(3.24kΩ)

5.6kΩ

(5.49kΩ)

3.32V

4.70kΩ

7.91kΩ

 

4.7kΩ

 

 

1.96kΩ

3.30kΩ

 

 

3.3kΩ

 

2.79kΩ

4.70kΩ

 

 

4.7kΩ

 

3.33kΩ

5.60kΩ

 

3.3kΩ

(3.24kΩ)

5.6kΩ

(5.49kΩ)

3.32V

1.1kΩ 1.851kΩ   1.1 1.87kΩ 3.32V
1.2kΩ 2.020kΩ   1.2 2.05kΩ 3.33V
1.3kΩ 2.187kΩ   1.3 2.20kΩ 3.31V
1.5kΩ 2.524kΩ   1.5 2.55kΩ 3.32V

 

 

For 5.0V output

 

Commercial Resistor value

Actual Output

R1

R2

 

R1

R2

Vout

1.00kΩ

3.07kΩ

 

1.0kΩ

 

 

3.30kΩ

10.10kΩ

 

3.3kΩ

(3.24kΩ)

10.0kΩ

(10.00kΩ)

4.96V

4.70kΩ

14.40kΩ

 

4.7kΩ

 

 

1.08kΩ

3.30kΩ

 

 

3.3kΩ

 

1.53kΩ

4.70kΩ

 

 

4.7kΩ

 

1.83kΩ

5.60kΩ

 

 

5.6kΩ

 

3.26kΩ

10.00kΩ

 

3.3kΩ

(3.24kΩ)

10.0kΩ

(10.00kΩ)

4.96V

 

 

    please refer to the table for resistors in parallel for more resistance design options.

    please refer to above for design calculator for resistance value selective

 

   

LM2594 (0.5A)

DC to DC step down voltage regulator.

Wide input voltage 8Vdc to 37Vdc (up to 60V for HV version).

 

 

Part number:

- LM2594-3.3 (3.3Vdc output)

- LM2594-5.0 (5Vdc output)

- LM2594-12 (12Vdc output)

- LM2594-ADJ (1.23Vdc to 37Vdc output) (57V for HV version)

 

 

Package: SOIC8, DIP8

LM2594 datasheet

 

Component list

Symbol

Component  

C1

68uF (50V aluminium electrolytic)  
C2

120uF (16V aluminium electrolytic, low ESR)

 
D1 1N5817 (schottky diode 1A)  
L1

100uH, 0.5A

 
     
     

 

   

LM2596 (3A)

DC to DC step down voltage regulator.

Wide input voltage 8Vdc to 40Vdc.

 

 

Part number:

- LM2596-3.3 (3.3Vdc output)

- LM2596-5.0 (5Vdc output)

- LM2596-12 (12Vdc output)

- LM2596-ADJ (1.23Vdc to 37Vdc output)

 

 

Package: TO-220 (T)

LM2596 datasheet

 

Component list

Symbol

Component  

C1

680uF (50V aluminium electrolytic)  
C2

330uF (100V aluminium electrolytic, low ESR) <for LM2596-3.3, LM2596-5.0>

180uF (100V aluminium electrolytic, low ESR)<for LM2596-12>

 
D1 1N5824 (schottky diode 4A)  
L1

33uH, 3A  <for LM2596-3.3, LM2596-5.0>

68uH, 3A  <for LM2596-12>

 
     
     

 

   

LM2678 (5A)

DC to DC step down voltage regulator.

Wide input voltage 8Vdc to 40Vdc.

 

 

Part number:

- LM2678-3.3 (3.3Vdc output)

- LM2678-5.0 (5Vdc output)

- LM2678-12 (12Vdc output)

- LM2678-ADJ (1.2Vdc to 37Vdc output)

 

 

Package: TO-220

LM2678 datasheet

 

Component list

Symbol

Component  

C1

45uF (50V aluminium electrolytic) + 0.47uF  

C2

10nF (50V ceramic, low ESR)  
C3

360uF (100V aluminium electrolytic, low ESR) <for LM2678-3.3, LM2678-5.0>

220uF (100V aluminium electrolytic, low ESR)<for LM2678-12>

 
D1 6TQ045S (schottky diode 6A)  
L1

15uH, 5A  <for LM2678-3.3, LM2678-5.0>

22uH, 5A  <for LM2678-12>

 
     
     

 



LM2574 (0.5A)

DC to DC step down voltage regulator.

Wide input voltage 4.5Vdc to 42Vdc.

 

 

Part number:

- LM2574-5.0 (5Vdc output)

- LM2574-ADJ (1.2Vdc to Vin output)

 

Alternative:

NJM2369A, NJM2374A

 

Package: Wide-SOIC14

wide_soic14

 lm2574-adj circuit
LM2574 datasheet


Click for LM2574-adj circuitlm2574-adj circuit


Component list

Please see the section for LM2574, LM2576. They are similar.




LM22674 (0.5A)

DC to DC step down voltage regulator.

Wide input voltage 4.5Vdc to 42Vdc.

 

 

Part number:

- LM22674-5.0 (5Vdc output)

- LM22674-ADJ (1.2Vdc to Vin output)

 

 

Package: PSOP8

LM22674 datasheet

 

Component list

Symbol

Component  

C1

22uF (50V aluminium electrolytic) + 1uF (50V ceramic, low ESR)  

C2

10nF (50V ceramic, low ESR)  
C3 22uF (50V aluminium electrolytic) + 1uF (50V ceramic, low ESR)  
D1 1N5819 (schottky diode 1A)  
L1 39uH (>0.5A)  
R1, R2 <For 3.3Vout> R1=976Ω, R2=1.54kΩ (1/8watt)  

for Vout R1 R2 computation reference, refer to LM22676 section
     

 

   

LM22675 (1A)

DC to DC step down voltage regulator.

Wide input voltage 4.5Vdc to 42Vdc.

 

 

Part number:

- LM22675-5.0 (5Vdc output)

- LM22675-ADJ (1.285Vdc to Vin output)

 

 

Package: PSOP8

LM22675 datasheet

 

Component list

Symbol

Component  

C1

22uF (50V aluminium electrolytic) + 1uF (50V ceramic, low ESR)  

C2

10nF (50V ceramic, low ESR)  
C3 120uF (16V aluminium electrolytic) + 1uF (50V ceramic, low ESR)  
D1 1N5822 (schottky diode 2 to 3A)  
L1 22uH (>1A)  
R1, R2 <For 3.3Vout> R1=976Ω, R2=1.54kΩ (1/8watt)  

for Vout R1 R2 computation reference, refer to LM22676 section
     

 

   

LM22676 (3A)

DC to DC step down voltage regulator.

Wide input voltage 4.5Vdc to 42Vdc.

 

 

Part number:

- LM22676-5.0 (5Vdc output)

- LM22676-ADJ (1.285Vdc to Vin output)

 

 

Package: PSOP8

TO-263 thin (7 pin)

LM22676 datasheet

 

Component list

Symbol

Component  

C1

22uF (50V aluminium electrolytic) + 2.2uF (50V ceramic, low ESR)  

C2

10nF (50V ceramic, low ESR)  
C3 120uF (50V aluminium electrolytic) + 2.2uF (50V ceramic, low ESR)  
D1 50WQ03 (schottky diode 5.5A)  
L1 8.2uH (>5.5A)  
R1, R2 <For 3.3Vout> R1=976Ω, R2=1.54kΩ (1/8watt)  
  <For 5.0Vout> R1=1kΩ, R2=2.89kΩ  




The following guide uses typical resistor value.


<For 3.21Vout> R1=1kΩ, R2=1.5kΩ
<For 3.26Vout> R1=1kΩ, R2=1.54kΩ
<For 3.31Vout> R1=976Ω, R2=1.54kΩ
<For 3.34Vout> R1=1kΩ, R2=1.6kΩ
<For 3.39Vout> R1=1.1kΩ, R2=1.8kΩ
<For 3.41Vout> R1=2kΩ, R2=3.3kΩ
<For 3.47Vout> R1=3.3kΩ, R2=5.6kΩ
<For 5.06Vout> R1=1.6kΩ, R2=4.7kΩ
<For 5.14Vout> R1=1kΩ, R2=3kΩ
<For 5.14Vout> R1=1.1kΩ, R2=3.3kΩ
<For 5.16Vout> R1=1.54kΩ, R2=4.64kΩ
<For 5.21Vout> R1=1.54kΩ, R2=4.7kΩ
<For 5.23Vout> R1=976Ω, R2=3kΩ





Formula for LM22676-ADJ version (for Vout < 5V)
R1=(R2/((Vout/VFB)-1))
R2=R1((Vout/VFB)-1)
Vout=VFB((R2/R1)+1),     where VFB=1.285V,
                                         R1+R2 is about 3kΩ & must be <10kΩ

 

   

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LM22678 (5A)

DC to DC step down voltage regulator.

Wide input voltage 4.5Vdc to 42Vdc.

 

 

Part number:

- LM22678-5.0 (5Vdc output)

- LM22678-ADJ (1.285Vdc to Vin output)

 

 

Package: TO-263 thin (7 pins)

 

LM22678 datasheet

 

Component list

Symbol

Component  

C1

22uF (50V aluminium electrolytic) + 2.2uF (50V ceramic, low ESR)  

C2

10nF (50V ceramic, low ESR)  
C3 180uF (16V aluminium electrolytic) + 2.2uF (50V ceramic, low ESR)  
D1 50WQ03 (schottky diode 5.5A)  
L1 4.7uH (8.5A)  
R1, R2 <For 3.3Vout> R1=976Ω, R2=1.54kΩ (1/8watt)  

for Vout R1 R2 computation reference, refer to LM22676 section

     

 

   

MC34063 (1.5A)

DC to DC step down/up.invert voltage regulator.

Wide input voltage 3.0Vdc to 40Vdc.

 

 

Part number:

- MC34063A, MC33063A

- SC34063A, SC33063A

- NCV33063A

 

 

Package: SOIC-8, PDIP-8, DFN8 (8 pins)

 

mc34063 pinout

mc34063 package

 

 

mc34063 pic

mc34063 pic

Load regulation performance measured seems poor. Ideally, this is a 5V 0.5A voltage regulator.

1) Vin=10V, Vout=4.92Vdc, Load=opened circuit (0A)

R2=10kΩ, R1=3.3kΩ, Rsc=0.33Ω 0.5W, L=330uH

2) Vin=10V, Vout=4.10Vdc, Load=15Ω (0.27A)

3) Vin=10V, Vout=3.00Vdc, Load=10Ω (0.3A)

 

Seems that the circuit can only handle 0.1-0.2A load. The voltage regulation is quite poor. According to the document, it is ok for the inductance to be higher. Could it be that my R1 & R2 value being too high? I need to check it up.

 

 

Circuit 1: Step down dc-dc 25Vin -> 5Vout (0.5A) mc34063 circuit1

Current rating can be boost by using external transistor to drive the load.

Adjustable Vout computation (very similar to LM2576, LM2575) with Vref = 1.25V

Vout = 1.25 [1+(R2/R1)]

R2 = R1 [(Vout/1.25)-1)]

<For 3.3Vout> R1=3.3kΩ, R2=5.6kΩ
<For 5.0Vout> R1=3.3kΩ, R2=10kΩ

<For 0.5A Iout> Rsc = 0.3 / (2*Iout) = 0.3 / (2*0.5A) = 0.3Ω (0.075W), please note that Iout < 1.5A using internal driver.

Circuit 2: Step up dc-dc 12Vin -> 28Vout (0.175A) mc34063 circuit2

 

Circuit 3: Step up inverting dc-dc 4.5-6Vin -> -12Vout (0.1A) mc34063 circuit3

mc34063 ic circuit

 

 

MC34063A-D datasheet

MC34063 project example.pdf

MC34063 AN10360, Schottky rectifiers for DCDC converters.pdf

MC34063 AN920-D, Theory and Applications.pdf

MC34063 slva252b, Application Switching Regulator.pdf

 

   

NCP3063 (1.5A)

DC to DC step down/up.invert voltage regulator.

Wide input voltage up to 40Vdc. Almost similar to MC34063 dc-dc ic.

 

 

Part number:

- NCP3063, NCP3063B, NCV3063

 

 

Package: SOIC-8, PDIP-8, DFN8 (8 pins)

 

NCP3063 pinout

.NCP3063 package

NCP3063 is very similar to MC34063. Please refer to MC34063 for some handy information.

NCP3063 circuit

NCP3063 ic circuit

NCP3063 datasheet



LMZ14203 (3A)

DC to DC step down voltage regulator.

Wide input voltage 6Vdc to 42Vdc.
 

 

Part number:

- LMZ14203TZ-ADJ (0.8Vdc to 6Vdc output)



Package: TO-PMOD (7 pins)


lmz14203 package

lmz14203 circuit
LMZ14203 datasheet
   

LMZ14201 (1A)

DC to DC step down voltage regulator.

Wide input voltage 6Vdc to 42Vdc.
 

 

Part number:

- LMZ14201H (5Vdc to 30Vdc output)



Package: TO-PMOD (7 pin)

 

lmz14201H

lmz14201h

 

LMZ14201H datasheet

 

   

LMZ12003 (3A)

DC to DC step down voltage regulator.

Wide input voltage 4.5Vdc to 20Vdc.

 

 

Part number:

- LMZ12003TZ-ADJ (0.8Vdc to 6Vdc output)


Package: TO-PMOD (7 pin)

lmz12003 package
lmz12003 circuit
LMZ12003 datasheet
   

LM3102 (2.5A)

DC to DC step down voltage regulator.

Wide input voltage 4.5Vdc to 42Vdc.

 

 

Part number:

- LM3102MH

 

Package: TSSOP (20 pin)

LM3102 datasheet

   

LM2577 (3A)

DC to DC step up voltage regulator.

Wide input voltage 3.5Vdc to 40Vdc.

 

 

Part number:

- LM2577-12 (12Vdc output)

- LM2577-15 (15Vdc output)

- LM2577-ADJ (1.23Vdc to 37Vdc output)

 

 

Package: TO-220 (T)

 

tested working on 2006

tested working on 2007-06-21

tested working on 2007-06-21

LM2577 datasheet

Click for LM2577-adj circuit

Click for LM2577-adj layout

 

Component list

Symbol

Component  
- 0.1uF  
- 0.33uF  
-

680uF (50V aluminium electrolytic)

 
- 1N5822 (schottky diode 3A)  
-

100uH, 3A

 
- 2.2kΩ 1/4W resistor  
- "for LM2577-adj IC" 20kΩ multi-turn variable resistor, set to ratio to R2=2kΩ, R1=18kΩ for voltage output of 12Vdc before soldering.  

 

   
MAX1708 (2A, 10W)

DC to DC step up voltage regulator.

Low input voltage 0.7-5.0Vdc

to output voltage 2.5-5.5Vdc

Suitable for battery powered circuit.

 

 

Part number:

- MAX1708EEE

 

 

Package: QSOP16

Front (tested with current up to 0.05A. Perheps the inductor used is not correct.)

QSOP IC mounted at the back of PCB.

MAX1708 datasheet

Click for MAX1708 circuit

 

 

   
NCP1400a (0.1A)

DC to DC step up voltage regulator.

Low input voltage from 0.8Vdc

to output voltage 1.9-5.5Vdc

Suitable for battery powered circuit.

 

 

Package: SOT23-5

 

Not tested.

2005-NCP1400a datasheet.pdf
   
MCP1640 (0.8A)

DC to DC step up voltage regulator.

Low input voltage from 0.35Vdc

to output voltage 2.0-5.5Vdc

Suitable for battery powered circuit.

 

 

Package: SOT23-6, DFN

 

Not tested.

Output 3.3V from a 1.2V alkaline battery using MCP1640

Output 5.0V from a 3.2V LI-ION battery using MCP1640

 

MCP1640.pdf

   
LM2731 (1.8A) 

DC to DC step up voltage regulator.

Low input voltage from 2.7-14Vdc

to output voltage up to 20Vdc

Suitable for battery powered circuit.

Li-Ion, Li-Po

NOTE!!! (!SHDN pin does not shutdown the output. When shutdown pin is activated, Vout=Vin-0.2V. Vout will be close to Vin instead of pumping up to a higher voltage when shutdown pin is pull to low.)

 

 

 

Package: SOT23-5

 

5V output version

This board uses inductor from BOURNS SDR0403-6R8ML (RMS Current (Irms): 1.41A, Saturation Current (Isat): 2.1A )

12V output version

LM2731.pdf

Note: The size of the inductor plays an important part in determine the load's max current.(applies to all switching regulators)

 

   
LM3478

DC to DC step up voltage regulator.

Low input voltage from 2.97Vdc

to output voltage up to 40Vdc


 

Package: SOIC-8, VSSOP-8

lm3478 pin out

lm3478%20circuit1.JPG

lm3478%20circuit2.JPG

dc-dc 5V to 12V
LM3478 datasheet
LM3478 5V-12V application notes


lm3478%20circuit%20layout.jpg

Load used (Ohm)Vout with 100uF, 47uFVout with 100uF, 47uF, 47uF, 100nF
1kohm
Input = 5V, ??A
Output = 12.4V, 12mA
lm3478%20TEK0000,%201Kohm%20load.giflm3478%20TEK0004,%201kohm%20with%20more%20capacitors.gif
12ohm
Input = 5V, 2A
Output =  10.7V, 0.9A
lm3478%20TEK0001,%2012ohm%20load.giflm3478%20TEK0002,%2012ohm%20load.giflm3478%20TEK0005,%2012ohm%20with%20more%20capacitors.gif
24ohm
Input = 5V, 1.5A
Output =  12.0V, 0.5A
lm3478%20TEK0003,%2024ohm%20load.giflm3478%20TEK0009,%2024ohm%20with%20more%20capacitors.gif




LT1308 (1A)

DC to DC step up voltage regulator.

Low input voltage from 1Vdc

to output voltage up to 3.3V 0.3A, 5.0Vdc 1A)

Suitable for battery powered circuit.

Li-Ion, Li-Po, NiCd

 

 

 

Package: SOIC-8

 

 

LT1308.pdf

   
LT1301 (0.12A)

DC to DC step up voltage regulator.

Low input voltage from 1.8Vdc

to output voltage 5V or 12Vdc 120mA

Suitable for battery powered circuit.

Li-Ion, Li-Po

 

 

 

Package: SOIC-8

 

LT1301.pdf

   
Simple DC-DC step up voltage IC

MAX662A 4.5-5.5V to 12V (30mA), no need inductor

MAX734 4.75V - 12V to 12V (120mA)

MAX761 2-16.5V to 12V (150mA)

MAX732 4V - 9.3V to 12V (200mA)

MAX762 2-16.5V to 15V/Adj (150mA)

 

 

 
Ultra Low Drop Regulator MIC5219 (good for Li-Po battery which has a very low voltage)  
 

 

 

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Diode selection references  

Schottky diode (1A)

1N5817, 1N5818, 1N5819, MBR120P, MBR130P, MBR140P, MBR150, MBR160, SR102, SR103, SR104, SR105, SR106, 11DQ03, 11DQ04, 11DQ05, 11DQ06

(smd alternative to 1N5819) MBRS140T3G, SS12, SS13, SS14, SK12, SK13, SK14

Schottky diode (3A)

1N5820, 1N5821, 1N5822, MBR320, MBR330, MBR340, MBR350, MBR360, SR302, SR303, SR304, SR305, SR306, 31DQ03, 31DQ04, 31DQ05, 31DQ06

(smd alternative to 1N5820, 1N5821, 1N5822) MBRS320T3, MBRS330T3, MBRS340T3, SS32, SS33, SS34, SK32, SK33, SK34

Schottky diode (4A-6A)

1N5823, 1N5824, 1N5825, 50WQ03, 50WQ04, 50WQ05, 50WR06, 50SQ060, MBR340

 

Diode references from Diotec     

- diotec diode cross reference list.pdf

- diotec diode case reference.pdf

- diotec diode smd selection.pdf

- diotec transistors-diodes zener selection.pdf

- diotec diode bridges selection.pdf

- diotec smdbridges.pdf

- diotec diode axial.pdf

- diotec hv-diac.pdf

- diotec arrays-special.pdf

 

Resistor selection references

 

 

 

 

 

 

Resistor Colour Codes

 

Images taken Farnell.

 

 

 

 

 

 

 

Introducing the types of resistors

W series- Vitreous enamelled wirewound resistors offering high power, high stability and reliability. Suit for use in harsh environment.

WH series- Aluminium clad resistors for applications where high power dissipation in a small space is required.

MFR series- High stability metal film resistors offering higher performance than carbon film with very low noise levels and high reliablility.

RC series- Very high stability metal film resistors offering very high reliability and tight tolerances.

WCR series- Surface mount resistors suitable for automatic placement. Features include nickel barriers, wide ohmic range and high reliability.

The DC-DC converter design for the adjustable IC version, you may need the following resistor standard EIA decade resistor values for references. Long time ago, when technology is not so advance, resistor manufacturing is not unable to produce precise resistor value, as in today. Due to its large variation in tolerance, the resolution of the range of standard resistor value is limited. Example is E3 series having tolerance of 50%, which have only resistors in decade of 100, 220, 470. There is not much point to define or differential between 100Ω and 101Ω, having a tolerance of 50%. With such high tolerance, there is hardly any difference between 100Ω and 101Ω. They should both belongs to the same class of 100Ω

The standard EIA decade resistor value is group into different series. Each is grouped according to their tolerance level. The higher the tolerance, the higher the resistor value resolution will be. The common resistor value range would be the E24 (tolerance 5%) and E96 (tolerance 1%) series.

To find the range of resistor value that is available in the industrial, multiply the normalise standard found in the table in terms of 100, 1000

- Example: E24 series referring to normalise value 1.0

   It means that under E24 series, you should be able to find these Ω range 100Ω, 1000Ω, 1kΩ, 10kΩ, 100kΩ, 1MΩ, 10MΩ, 100MΩ. Other resistor value under E24 can be determine from the rest of the normalised value in the table below. Lower Ω are not available in the series as they should be in resistor package for higher wattage

 

Standard EIA Decade Resistor Values

E24 (preferred standard resistor values with 5% tolerance)

1.0 1.1 1.2 1.3 1.5 1.6 1.8 2.0 2.2 2.4 2.7 3.0
3.3 3.6 3.9 4.3 4.7 5.1 5.6 6.2 6.8 7.5 8.2 9.1

E96 (preferred standard resistor values with 1% tolerance)

1.00 1.02 1.05 1.07 1.10 1.13 1.15 1.18 1.21 1.24 1.27 1.30
1.33 1.37 1.40 1.43 1.47 1.50 1.54 1.58 1.62 1.65 1.69 1.74
1.78 1.82 1.87 1.91 1.96 2.00 2.05 2.10 2.15 2.21 2.26 2.32
2.37 2.43 2.49 2.55 2.61 2.67 2.74 2.80 2.87 2.94 3.01 3.09
3.16 3.24 3.32 3.40 3.48 3.57 3.65 3.74 3.83 3.92 4.02 4.12
4.22 4.32 4.42 4.53 4.64 4.75 4.87 4.99 5.11 5.23 5.36 5.49
5.62 5.76 5.90 6.04 6.19 6.34 6.49 6.65 6.81 6.98 7.15 7.32
7.50 7.68 7.87 8.06 8.25 8.45 8.66 8.87 9.09 9.31 9.53 9.76

Tolerance Codes

B=0.1%, C=0.25%, D=0.5%, F=1%, G=2%, J=5%, K=10%, M=20%

website references:

- http://sound.westhost.com/miscc.htm

- http://www.logwell.com/tech/components/resistor_values.html

Most common resistance stock available:
0, 1, 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 75, 82, 100, 120, 150, 180, 200 ,220 ,270, 330, 390, 470, 560, 680, 750, 820, 1k, 1.1k, 1.2k, 1.3k, 1.5k, 1.8k, 2k, 2.2k, 2.7k, 3.3k, 3.9k, 4.7k, 5.6k, 6.8k, 7.5k, 8.2k, 10k, 11k, 12k, 13k, 15k

Second common resistance stock available:
0.1, 0.15, 0.22, 0.33, 0.47, 0.68, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2, 11, 20, 49.9, 51, 62, 110, 124, 160, 240, 249, 300, 360, 392, 430, 475, 499, 510, 620, 681, 910, 1.02k, 1.24k, 1.33k, 1.62k, 1.82k, 2.21k, 2.4k, 2.49k, 2.74k, 3k, 3.01k, 3.24k, 3.32k, 3.6k, 3.92k, 4.02k, 4.22k, 4.3k, 4.75k, 4.87k, 4.99k, 5.1k, 5.11k, 5.62k, 5.76k, 5.9k, 6.04k, 6.19k, 6.2k, 6.34k, 6.49k, 6.65k, 6.81k, 7.32k, 8.06k, 8.25k, 9.1k, 9.53k, 10.2k

 

Commercial Stock Availiability Statistics from element14 24 Oct 2013, for resistor value >40 types availability.

1Ω 10Ω 12Ω 15Ω 18Ω 22Ω 27Ω 33Ω 39Ω 47Ω 56Ω 68Ω
46 81 50 66 44 62 49 59 51 62 51 60
                       
75Ω 82Ω 100Ω 120Ω 150Ω 180Ω 200Ω 220Ω 270Ω 330Ω 390Ω 470Ω
41 54 100 61 79 59 48 67 60 70 53 78
                       
560Ω 680Ω 750Ω 820Ω 1KΩ 1K1Ω 1K2Ω 1K3Ω 1K5Ω 1K8Ω 2KΩ 2K2Ω
56 62 48 64 132 48 67 43 89 64 69 80
                       
2K4 2K7 3K 3K3 3K9 4K7 5K1 5K6 6K2 6K8 7K5 8K2Ω
45 64 39 76 63 87 41 67 39 80 51 63
                       
10KΩ 11KΩ 12KΩ 13KΩ 15KΩ 18KΩ 20KΩ 22KΩ 24KΩ 27KΩ 33KΩ 39KΩ
132 52 70 45 88 63 63 75 40 61 73 62
                       
47KΩ 51KΩ 56KΩ 62KΩ 68KΩ 75KΩ 82KΩ 100KΩ 110KΩ 120KΩ 130KΩ 150KΩ
79 39 61 39 63 48 57 122 41 47 44 68
                       
180KΩ 200KΩ 220KΩ 270KΩ 330KΩ 390KΩ 470KΩ 560KΩ 680KΩ 820KΩ 1MΩ  
46 49 57 46 58 46 55 46 51 44 70  


Table for resistor in parallel

This resistor table is interesting. While dealing with circuits prototype, I often need to use resistor value that may not be common. To keep sufficient stock for all resistor range is a bit too much to manage. A larger and better storage system will be needed. I find it difficult to manage the wide range of resistor. This brings me the idea of forming the required resistance from two commonly stocked resistor connecting in parallel. This means that I can keep fewer resistance range and easily stock larger quantity for each value.

On the following table, the 1st row and column represents the common resistor value that I normally keep stock. The rest of the cells present the various possible resistance I can obtain by having the resistance in parallel from the respective row and column. The computation is done in the microsoft excel sheet. formula: "=($A2*B$1)/($A2+B$1)". Those value highlighted in yellow are quite useful when designing my adjustable DC-DC circuit when I do not have the stock for the resistor that is not commonly in use.

0Ω 10Ω 47Ω 100Ω 120Ω 330Ω 470Ω 560Ω 1kΩ 3k3Ω 4k7Ω 5k6Ω 10kΩ 100kΩ 1MΩ
10Ω 5                          
47Ω 8 24                        
100Ω 9 32 50                      
120Ω 9 34 55 60                    
330Ω 10 41 77 88 165                  
470Ω 10 43 83 96 194 235                
560Ω 10 43 85 99 208 256 280              
1kΩ 10 45 91 107 248 320 359 500            
3k3Ω 10 46 97 116 300 411 479 767 1k65          
4k7Ω 10 47 98 117 308 427 500 825 1k94 2k35        
5k6Ω 10 47 98 117 312 434 509 848 2k08 2k56 2k80      
10kΩ 10 47 99 119 319 449 530 909 2k48 3k20 3k59 5k00    
100kΩ 10 47 100 120 329 468 557 990 3k19 4k49 5k30 9k09 50k0  
1MΩ 10 47 100 120 330 470 560 1k00 3k29 4k68 5k57 9k90 90k9 500k

 

Capacitor selection references
Typical aluminum electrolytic capacitor size
- Capacitor Vishay datasheet

Standard size:

Case Size
Case code
5x11 11
6.3x11 12
8x11.5 13
10x12 14
10x16 15
10x20 16
13x20 17
13x25 18
16x25 19
16x31 20
16x35 21
18x35 22
18x40 23








   

 

 

 

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Other Step up DC-DC conversion
 

Ultra-Miniature High Voltage Power Supplies

Q Series

Q01-5 (5Vdc to 100Vdc)

 

 

 

email:    contact->email_siongboon  

website: http://www.siongboon.com


 

 

Keyword: Buck Regulator, voltage regulator, switching mode power supply, High efficiency, voltage supply, dc-dc converter, LM2576 LM2575 IC, regulated 5Vdc output, Shottky diode, 100uH, 330uH inductor, Low cost, 1A 3A.