Showing posts with label Switched-Mode PS. Show all posts
Showing posts with label Switched-Mode PS. Show all posts

Wednesday, June 22, 2022

5A, 1.22V to 26V, 500kHz Step-Down Converter Using RT8289 IC with PCB

Fig. 1 - 5A, 1.22V to 26V, 500kHz Step-Down Converter Using RT8289 IC with PCB

This is a DC-DC 5A, 1.22V to 26V, 500kHz Step-Down Converter Using RT8289 IC, it works with a Step-Down conversion system.

This powerful chip manages to work with very few external components and provides a preset voltage between 1.22V to 26V, with 5 Amps of output current.

General  IC Description

The RT8289 is a step-down regulator with an internal Power MOSFET. It achieves 5A of continuous output current over a wide input supply range with excellent load and line regulation. 

Current mode operation provides fast transient response and eases loop stabilization. The RT8289 provides protections such as cycle-by-cycle current limiting and thermal shutdown. 

In shutdown mode, the regulator draws 25A of supply current. The  RT8289  requires  a  minimum  number  of  external components, to provide a compact solution. The  RT8289  is  available  in  a  SOP-8  (Exposed  Pad) package.

Features

  • High Output Current up to 5A
  • Internal Soft-Start
  • 100mΩ Internal Power MOSFET Switch 
  • Internal  Compensation  Minimizes  External  Parts Count
  • High Efficiency up to 90%
  • 25μA Shutdown Current
  • Fixed 500kHz Frequency
  • Thermal Shutdown Protection
  • Cycle-by-Cycle Over Current Protection
  • Wide 5.5V to 32V Operating Input Range
  • Adjustable Output  Voltage from 1.222V to 26V
  • Available in an SOP-8 (Exposed Pad) Package
  • RoHS Compliant and Halogen Free

Output Voltage Setting

To define the output voltage, we use a voltage divider formed by 2 resistors, R1 and R2, this allows the FB pin of the integrated circuit to detect changes in the output voltage, and recalibrate the circuit keeping it stabilized.

To set this output voltage, we can calculate the external resistive divider, according to the equation formulated below:

  • VOUT = VREF *(1 + (R1/R2))
    • Where VREF is the reference voltage (type 1.222V).
    • Where R1 = 10kΩ.
We exemplify in our circuit, the voltage divider is formed by R1 and R2.

General Formula:

  • VOUT = VREF *(1 + R1/R2)
  • Where VREF is the reference voltage (type 1.222V).
  • Where R1 = 10kΩ.

For a 3.3V output, our formula would look like:

  • Vout = 1,222 * (1+ (10/5.8))
  • Vout = 3.328V

For a 5V output, our formula would look like:

  • Vout = 1,222 * (1+ (10/3.16))
  • Vout = 5,089V

For a 9V output, our formula would look like:

  • Vout = 1,222 * (1+ (10/1.57))
  • Vout = 9,005V

For a 12V output, our formula would look like:

  • Vout = 1,222 * (1+ (10/1.13))
  • Vout = 12,036V

For a 26V output, our formula would look like:

  • Vout = 1,222 * (1+ (10/0.493))
  • Vout = 26,009V
We may be using a trimpot instead of R2, this allows you to vary the output voltage through the Trimpot.

The Circuit Schematic

In Figure 2, below, we can see the schematic diagram of the Low Noise and High Frequency 5A DC-DC Step-Down Converter

All circuit components are SMD, except the terminal blocks, “optional”, you can solder directly to the board. This type of SMD circuit is great to be implemented in miniaturized circuits.

It is preferable to use tantalum capacitors, but if you cannot find them, electrolytic capacitors can be used, but for more sensitive circuits, we recommend using tantalum.

The DC-DC converter supports input from 5.5V to 32V, and at the output it maintains the preset voltage completely stabilized.
Fig. 2 - Schematic 5A, 1.22V to 26V, 500kHz Step-Down Converter Using RT8289 IC

Printed Circuit Board

In Figure 3, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass. 

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

The PCB tracks are doubled, the main ones have their tracks on the bottom and top of the PCB as the current is 5 amps.

Fig. 3 - PCB 5A, 1.22V to 26V, 500kHz Step-Down Converter Using RT8289 IC

Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

If you have any questions, suggestions or corrections, please leave them in the comments, and we will answer them soon.

Subscribe to our blog!!! Click Here - elcircuits.com!!!

My Best Regards!!!

Wednesday, May 18, 2022

Electronic Resistive Load - 50A Power Supply Test with PCB

Fig. 1 - Electronic Resistive Load - 50A Power Supply Test with PCB

You know that moment when you have a power supply to fix, you do the service and the supply works, but you don't know if it will support a large load?

I came across a problem like this, and I decided to make my own resistive electronic load, and share it with our subscribers, and for you who visit us, welcome!

The circuit

The circuit is quite simple, with few components and easy to assemble, based on two power transistors Mosfet N-channel, IRL44N connected in parallel.

The circuit is capable of withstanding an initial load “for low voltage sources 4V” of 40A, and for voltage above 5V, the current is 50A, supporting voltages up to 45V.

This voltage is received and transformed into heat, and the consumption current is controlled by means of a potentiometer.

Transistor Description

Fifth Generation HEXFETs from International Rectifier utilize advanced processing techniques to achieve the lowest possible on-resistance per silicon area.

This benefit, combined with the fast switching speed and ruggedized device design that HEXFET Power MOSFETs are well known for, provides the designer with an extremely efficient device for use in a wide variety of applications.

The TO-220 package is universally preferred for all commercial-industrial applications at power dissipation levels to approximately 50 watts.

The low thermal resistance and low package cost of the TO-220 contribute to its wide acceptance throughout the industry.

How it works

When turning on the electronic resistive load, a current passes through the Drain and Source taps, and this current flow is controlled by the Mosfet Gate.

For this control to happen properly, a stabilized voltage is needed at that point, which is done through the resistor R1, current limiting, in series with the zener diode, which stabilizes the voltage at the Gate.

This stabilized voltage ensures that the current not be variable when the input voltage undergoes some variation.

This stabilized voltage point is controlled by the potentiometer P1, which adjusts the voltage at the Gate of the Mosfet according to the required current.

It is worth remembering that the transistor used is a logic-type IRL44N Mosfet, not the well-known IRF44N

They differ in relation to the gate voltage, as the logic-type Mosfet triggers the Gate with low Vgs voltages from 4V, and the IRF44N does not work with such low voltages, the minimum Vgs is 7V.

The Circuit

The schematic diagram of the Electronic Resistive Load - Power Supply Test!, is shown in Figure 2 below, it is a simple circuit to assemble, there are few external components to solder, however it is a circuit of great quality and stability.
Fig. 2 - Electronic Resistive Load - 50A Power Supply Test

Component List

  • Semiconductors
    • Q1, Q2 .... IRL44N Mosfet Transistor
    • D1 ........... 1N4731 1W Zener Diode

  • Resistors
    • R1 ........ 1.8KΩ resistor (brown, grey, red, gold)
    • R2 ........ 0.22Ω resistor (red, red, silver, gold)
    • POT1 ... 220KΩ Potentiometer

  • Miscellaneous
    • P1 .... Screw Terminal Type 5mm 2-Pin Connector
    • Others .... PCB, Heat Sink, tin, wires, etc.

The PCB - Files to Download

In Figure 3, we provide the PCB - Printed Circuit Board, in GERBERPDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass. 

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

Fig. 3 - PCB Electronic Resistive Load - 50A Power Supply Test

Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files


If you have any questions, suggestions or corrections, please leave them in the comments, and we will answer them soon.

Subscribe to our blog! Click Here - elcircuits.com!

My Best Regards!

Saturday, February 26, 2022

4A Low-Noise High-Frequency Step-Up DC-DC Converter using MAX1709 with PCB

Fig. 1 - 4A Low-Noise High-Frequency Step-Up DC-DC Converter using MAX1709 with PCB

This is a DC-DC converter circuit that uses a MAX1709 series Integrated Circuit as the main component, it works with a Step-Up conversion system.

This powerful microcircuit is able to work with very few external components and deliver a fixed 3.3V or 5V or adjustable 2.5V to 5.5V voltage, with 4 Amperes of output current.

Integrated Circuit General Description

The MAX1709 sets a new standard of space savings for high-power,  step-up  DC-DC  conversion.  It  delivers  up to  20W  at  a  fixed  (3.3V  or  5V)  or  adjustable  (2.5V  to5.5V)  output,  using  an  on-chip  power  MOSFET  from  a +0.7V to +5V supply. 

Fixed-frequency PWM operation ensures that the switching noise spectrum is constrained to the 600kHz fundamental and its harmonics, allowing easy post filtering  for  noise  reduction.  

External  clock  synchronization capability  allows  for  even  tighter  noise  spectrum  control. Quiescent power consumption is less than 1mW to extend operating time in battery-powered systems. 

Two  control  inputs  (ONA ONB)  allow  simple  push-on, push-off  control  through  a  single  momentary  push button  switch,  as  well  as  conventional  on/off  logic  control. 

The  MAX1709  also  features  programmable  soft-start and current limit for design flexibility and optimum performance with batteries. 

The maximum RMS switch cur-rent  rating  is  10A.  For  a  device  with  a  lower  current rating, smaller size, and lower cost, refer to the MAX1708 datasheet.

The Circuit Schematic

In Figure 2, below, we can see the schematic diagram of 4A Low-Noise High-Frequency Step-Up DC-DC Converter using MAX1709.

The circuit is simple to assemble, there are few external components, and there is no need for adjustment, once assembled, it is ready to work, if everything is correct, of course!

The PCB tracks are bent, the main ones have their tracks at the bottom and at the top of the PCB, because the current is 4 amperes.

The capacitors are tantalum, however if you can't find them, electrolytic capacitors can be used, however for more sensitive circuits, the performance may not be as expected, but in most circuits they work very well.

The DC-DC converter supports input from 0.7V up to 5V, and at the output it maintains the stabilized voltage of 5V, however to get the promised 4 Amps, it is necessary to have at least 3.3V at the input.
Fig. 2 - Schematic Circuit 4A Low-Noise High-Frequency Step-Up DC-DC Converter using MAX1709

Components List

  • Semiconductors
    • U1 ...... MAX1709 SMD Integrated Circuit
    • D1 .....  B520C SMD Schottky Diode 5A

  • Resistor
    • R1 ..... 312KΩ SMD resistor (orange, brown, red, orange, gold
    • R2 ..... 2Ω SMD resistor (red, black, black, gold)
  • Capacitor
    • C1, C2, C6, C7 ... 150uF SMD Tantalum Capacitor
    • C3 ....................... 10nF SMD Ceramic Capacitor
    • C4 ....................... 220nF SMD Ceramic Capacitor
    • C5 ....................... 100nF SMD Ceramic Capacitor

  • Miscellaneous 
    • L1 .......... 1uH 5A SMD Inductor
    • P1, P2 .... 2-pin PCB soldering terminal blocks (Optional)
    • Others .... Printed Circuit Board, wires, etc.

Printed Circuit Board

In Figure 3, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass. 

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.
Fig. 3 - PCB - 4A Low-Noise High-Frequency Step-Up DC-DC Converter Using MAX1709

Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

Subscribe to our blog!!! Click Here - elcircuits.com!!!

My Best Regards!!!

Monday, December 6, 2021

Adjustable Switching Power Supply 5.1 to 40V, 2.5 Amp using L4960 + PCB

Fig. 1 - Adjustable Switching Power Supply 5.1 to 40V, 2.5 Amp using L4960

In this article, we present an adjustable power supply with a stabilized output that varies from 5.1 to 40V, with a current of 2.5 amps

This one can also have its stabilized voltage fixed, everything will depend on the type of project you are going to use.

The adjustable power supply is based on IC L4960 which is a monolithic power switching regulator IC, delivering 2.5A at a voltage variable from 5V to 40V in step down configuration.

Features of the device include current limiting, soft start, thermal protection and 0 to 100% duty cycle for continuous operation mode.

The complete schematic diagram of the power supply is shown below in Figure 2, it is a simple but complete power supply.

Fig. 2 - Schematic Adjustable Switching Power Supply 5.1 to 40V, 2.5 Amp using L4960

CIRCUIT OPERATION

The L4960 is a monolithic step down switching regulator providing output voltages from 5.1V to 40V and delivering 2.5A.

The regulation loop consists of a sawtooth oscillator, error amplifier, comparator and the output stage. An error signal is produced by comparing the output voltage with a precise 5.1V on-chip reference (zener zap trimmed to ± 2%).

This error signal is then compared with the sawtooth signal to generate the fixed frequency pulse width modulated pulses which drive the output stage.

The gain and frequency stability of the loop can be adjusted by an external RC network connected to pin 3. 

Closing the loop directly gives an output voltage of 5.1V. Higher voltages are obtained by inserting a voltage divider.

You may be interested in: 

Output overcurrent at switch on are prevented by the soft start function. The error amplifier output is initially clamped by the external capacitor Css and allowed to rise, linearly, as this capacitor is charged by a constant current source. Output overload protection is provided in the form of a current limiter.

The load current is sensed by an internal metal resistor connected to a comparator. When the load current exceeds a preset threshold this comparator sets a flip flop which disables the output stage and discharges the soft start capacitor. 

A second comparator resets the flip flop when the voltage across the soft start capacitor has fallen to 0.4V.

The output stage is thus re-enabled and the output voltage rises under control of the soft start network.

If the overload condition is still present the limiter will trigger again when the threshold current is reached. The average short circuit current is limited to a safe value by the dead time introduced by the soft start network. 

The thermal overload circuit disables circuit operation when the junction temperature reaches about 150°C and has hysteresis to prevent unstable conditions.

Efficient operation at switching frequencies up to 150KHz allows a reduction in the size and cost of external filter components.

The L4960 is mounted in a plastic Heptawatt power pack, and the pinouts are shown in Figure 3 below.

Fig. 3 -  L4960 IC Heptawatt Pinout

Download

We provide the files with the PCB, the schematic, the PDF, GERBER and JPG, PNG and provide a direct link for free download and a direct link, "MEGA".

Click on the direct link to download the files: Layout PCB, PDF, GERBER, JPG

Fig. 4 - Adjustable Switching Power Supply 5.1 to 40V, 2.5 Amp using L4960

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

Subscribe to our blog!!! Click Here - elcircuits.com!!!

My Best Regards!!!

Monday, September 14, 2020

How Switched Mode Power Supply Works - SMPS - ATX

ATX Switched-Mode Power Supplies have some interesting features when compared to standard Switched Mode Power Supply (SMPS).

In the ATX power supply, there are different output voltages: + 12V, + 5V, + 3.3V, -12V, -5V and 5VSB. There are some variations on these types of Power Supply, but in the general context, the pattern is this.
The way SMPS work is pretty much the same.
They control the output voltage by opening and closing the switching circuit so as to maintain the opening and closing time of this circuit, that is, the width of the pulses and their frequencies, to obtain the desired voltage.

There are separate processes for everything to work smoothly.
So let's see the modular diagram to unravel the steps of these processes so that we can step by step understanding.
This is the block in modules divided by steps, to improve our understanding.
 
 
There are 10 basic steps to running an ATX power supply, there are other underlying modules that are intrinsic in the steps, but, we'll not go as deep as it would be extremely great this Blogger, for those who want to watch the explanatory video with details in Portuguese. On the original post channel from YouTube.

Original Portuguese Version: Click Here

So let's understand these steps:

Step 1 - Transient Filter

Is through that stage that the voltage coming from your network, whether 110 or 220V AC should enter.
Transient Filter

This voltage goes through basic protection, the fuse, that if some step ahead short, the fuse opens, avoiding to burst everything ahead, and in the same line, we have the NTC (Negative Temperature Coefficient), It's a surge current limiter, in series with the electric circuit,

In it the value of ohmic resistance decreases as its temperature rises, its initial resistance is approximately 15 Ohms, which we can understand by the Ohms' law, the advantages one has in using it in series after the power supply switches it on lowers its resistance to approximately 0.5 Ohms.

EMI filters also exist, these are used to avoid high-frequency noise and a huge amount of harmonics generated by the switches that can propagate through the electrical network and cause interference in nearby electronic equipment.

Step 2 - Primary Rectification

Primary Rectification
 
In this stage we find the rectifier bridge or an arrangement formed by four common diodes, which has the function of rectifying a full-wave voltage, that is, rectifying an alternating electric current (AC), transforming it into a continuous electric current ( DC).

Step 3 - Filtration

Filtration
 
After rectification, the DC signal, Ripples (which are small variations, the capacitors are responsible for the filtering and stabilization IE, a decrease of these Ripples, in the rectified voltage, this voltage rises to something around 300V, which are used in the power switches, this part is fundamental to the correct stabilization of the source especially if its source is of high power.

Step 4 - Power Switches

Power Switches
 
These switches can be Bipolar Power Transistors such as MOSFETs, or any other type, but they differ from ordinary transistors, by the type of operation in which these transistors work, these switching transistors dissipate less power than a common working transistor in a linear source because they work as a switch on / off at high speeds, depending on the design of the source, they suffer variations that are usually between 20Khz to 100kHz, they are directly responsible for the output voltage, and stability of that voltage, through of the commands received by the Control Circuit.

Step 5 - Output Transformer

Output Transformer
 
The transformer is a high-frequency CHOPPER TRANSFORMER, and they also work with alternating voltage, when passing through the switches the voltage will be a square wave AC type PWM, but with high frequency, not with the same frequency of 60Hz of the input voltage.

The switches work on two different levels, High and Low, when it is HIGH, the voltage goes through it normally, causing a constant voltage level in the input of the coil of the transformer, the action of these transistors, goes from HIGH to LOW very quickly.

This will induce the winding to have the necessary voltages according to the winding and frequency placed on these switches.

Step 6 - Fast Rectifier

Fast Rectifier

With the voltage generated by high-frequency switches, a diode is needed to meet this demand, so we have the high-speed diodes called SCHOTTKY DIODES or fast recovery diodes since ordinary diodes would not be able to work with high-frequency voltages.

Step 7 - Output Filters

Output Filters

The inductor - This has the function of eliminating the high-frequency harmonics so that they do not travel to the equipment that will be fed, imagine if these harmonics pass to a micro-controller for example, could cause undue loads and errors of reading in the control processes.

And the Capacitors - They are the ones that filter and stabilize the voltage at the output, avoiding ripples and instabilities at the output.

Step 8 - Driver Transformer

Driver Transformer
 
The driver transformer in this case is nothing less than the one responsible for traffic the information coming from the Integrated Circuit Controller, and pass these commands to the switches, so as to bring insulation or electrical decoupling between primary and secondary, in this topology there is a pair of transistors that also switch the Transformer Drive to receive these PWM pulses from the driver IC, passing this information to the power step we already saw in Step 4.

Step 9 - PWM control

PWM control
 
The brain of a switched source is its PWM controller, they are dedicated integrated circuits, to perform that work, but they do not work alone, there are also current sensors, which also vary from source to source, but it is very likely that you will find in its source the TL341 IC, it has the aspect of a transistor, but, it is not a transistor, it is very popular for its cost-benefit.

This circuit is connected to the output of the power supply, receives Feedback, and directs the voltage information to the IC that controls the oscillator that generates a rectangular signal whose pulse width is controlled and sent to the Transformer Drive that sends these commands to the step of power.

If the power at the output to raise the voltage tends to drop, the circuit activates the instantaneous correction in the pulse width of the switching transistors and the voltage keeps stabilized.

Step 10 – Primary Power Supply VSB

Primary Power Supply VSB
 
VSB stands for Voltage Standby, which is technically a power supply that keeps its output active, whenever the source power cord is connected to the mains, its capacity is approximately 2 Amps, and this depends on the total power of the source, this active voltage line is to keep the circuit active and is necessary for when the power on button is activated through PSON, which is the start of the power supply, then the oscillator will activate the power line also powers the motherboard hardware to activate peripherals via software, keyboard, network, and so on.

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

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My Best Regards!!!