Friday, April 14, 2023

Mini Switching Power Supply 5V - 25V, 3A with TNY268 and PCB

Circuits to Assemble , Electronic Circuits
Mini Switching Power Supply 5V - 25V, 3A with TNY268 and PCB
Mini Switching Power Supply 5V - 25V, 3A with TNY268 and PCB

Para Versão em Portugues, clique aqui!

In this article, we will be discussing a mini switched power supply that provides 5V to 25Vdc output. This power supply is perfect for various electronic devices that require a stable and reliable power supply.

This is a power supply based on the TNY268 Integrated Circuit, which is part of a series of TinySwitch-II circuits: TNY263, TNY264, TNY265, TNY266, TNY267 and TNY268.

For a Flyback-type switched power supply like the one proposed, this IC is ideal, it integrates in its encapsulation the components necessary for it to work:
  • PWM Control, Power Mosfets
  • Overcurrent Protection
  • Over-Temperature Protection
  • Self-Feeding System
It does not need auxiliary windings, which makes it a complete IC, with DIP8 encapsulation, with a PWM working frequency of 132kHz and a voltage of up to 700V.

We will dive into the technical specifications, design, and features of this power supply and how it compares to other similar products in the market.

Technical Specifications

The mini switched power supply has an input voltage range of 80V to 260V AC, which makes it suitable for use in different parts of the world. 

It provides an output voltage that can be regulated between 5V to 25V, with a current of up to 3A, depending on the configuration that we choose.

The power supply also has short-circuit protection and overvoltage protection, ensuring the safety of the connected devices.

Design

The mini switched power supply has a compact design, with dimensions of 55mm x 26mm x 21mm. The power supply is enclosed in a plastic case that protects the circuitry from dust and other environmental factors. 

The power supply has a standard WJ2EDGVC-5.08-2P connector, making it easy to connect different electronic devices.

Caution!

"This circuit works directly connected to the electrical network, this is extremely dangerous, any carelessness, or wrong connections, design error, or any other occasion, can lead to irreversible damage.

We are not responsible for any type of occurrence. If you don't have enough experience, don't build this circuit, and if you build it, when testing it, be sure to have the proper protections and be accompanied by someone else."

Features

One of the standout features of this mini switched power supply is its efficiency. It has a high efficiency rating of up to 85%, which means that it wastes less energy as heat compared to other similar products.

This feature is especially important for electronic devices that are battery-powered, as it helps to extend their battery life.

Another feature of this power supply is its low ripple and noise. The power supply has a ripple voltage of less than 50mV, which ensures that the connected devices receive a stable and noise-free power supply. 

This is especially important for audio devices, where any noise in the power supply can cause unwanted noise in the audio output.

TNY268 - Pinout and Description

The TNY268 is packaged in a DIP-8B structure for perforated pinouts and an SMD-8B package for SMD.

The package is similar to the well-known IC LM555, with the exception of pin 6 hidden in the TNY268, as we can see in the pinout of Figure 2, below.

Fig. 2 - Pinout - Pinout TNY268

We leave below the description of each pin of the TNY268 Integrated Circuit to facilitate our understanding.

  • DRAIN (D): Power MOSFET drain connection. Provides internal operating current for start-up and steady-state operation.

  • BYPASS (BP): Connection point for an external 0.1 µF bypass capacitor for the internally generated 5.8 V supply.

  • ENABLE/UNDERVOLTAGE (EN/UV): This pin has two functions: input enable and line undervoltage detection. During normal operation, power MOSFET switching is controlled by this pin. MOSFET switching is terminated when a current greater than 240 μA is drawn from this pin.

    This pin also detects line undervoltage conditions through an external resistor connected to the DC line voltage. If there is no external resistor connected to this pin, TinySwitch-II detects its absence and disables the line undervoltage function.

  • SOURCE (S): Common control circuit, connected internally to the output MOSFET source.

  • SOURCE (HV RTN): MOSFET source connection output for high voltage feedback.

The Switched Power Supply Circuit


The Mini Switched Power Supply Circuit with TNY268 for 5V - 24V, 3A output is a simple yet powerful design, as shown in Figure 3 below. 

However, due to the involvement of electricity, it requires careful handling and at least intermediate knowledge of electronics to assemble the circuit.
Fig. 3 - Schematic Diagram Mini Switching Power Supply 5V - 25V, 3A with TNY268

The schematic diagram of the Mini Switched Power Supply Circuit is well laid out and easy to understand. It includes a TNY268 controller that regulates the output voltage and current of the power supply. 

The circuit has a few essential components such as capacitors, resistors, diodes, and an inductor, which work together to provide stable and efficient power.

Regulate The Output Voltage

The output voltage is adjusted through two parameters in the circuit:

  1. The D4 diode, which is a 1W Power Zener diode.
  2.  The secondary winding of the transformer.

The Zener Diode

The zener diode D4, is the diode that will adjust the output voltage, we must configure it as follows,
when the desired voltage is Xv, the zener diode must have a voltage Xv - 1.

The diode should be 1V lower than the nominal voltage of the power supply, this lower voltage is due to the photocoupler being connected in series with the zener diode, and since it is an “LED” diode, we have the voltage drop on it.

For example:

To obtain a voltage of 5V at the power supply output:
The zener diode D4 = 4V. We use a commercial 4.3V, 1N4731 zener diode.

To obtain a voltage of 9V at the power supply output:
The zener diode D4 = 8V. We use a commercial 8.2V, 1N4738 zener diode.

To obtain a voltage of 12V at the power supply output:
The zener diode D4 = 11V. We use a commercial 11V, 1N4741 zener diode.

To obtain a voltage of 25V at the power supply output:
The zener diode D4 = 24V. We use a commercial 24V, 1N4749 zener diode.

The Transformer

The transformer used in this circuit was a high frequency transformer, often found in PC power supplies, as illustrated in Figure 4 below, a model EE-25 Ferrite transformer.
Fig. 4 EE-25 Ferrite Transformer

Primary coil winding

The primary will be wound to support a voltage between 85V and 260V, and this will be done by winding 140 turns of 33AWG enamelled wire, or 0.18 mm diameter wire.

Right after winding the primary, place appropriate insulation tape, with electrical and thermal insulation, to insulate the primary from the secondary.

Secondary coil winding

The secondary will be wound according to the desired output voltage, and this will be done in such a way that, for each desired 1V, 1.4 turns of 17AWG enameled wire or 1.15 mm wire are wound.

The calculation for an output voltage of 5V can be achieved using the formula below:

Formula: N = V * F
  • N = Number of Turns
  • V = Desired Voltage
  • C = Constant = 1.4
  • V = 5V
  • C = 1.4
  • N = ?
  • N = 5 * 1.4
  • N = 7 laps
For 5V on the output, we have 7 turns to wind in the secondary.

The calculation for an output voltage of 9V:

  • V = 9V
  • F = 1.4
  • N = ?

  • N = 9 * 1.4
  • N = 12.6 = ~13 Rounds
For 9V on the output, we have 13 turns to wind in the secondary.

The calculation for an output voltage of 12V:

  • V = 12V
  • F = 1.4
  • N = ?

  • N = 12 * 1.4
  • N = 16.8 = ~17 Rounds
For 12V output, we have 17 turns to wind in the secondary.

The calculation for an output voltage of 24V:

  • V = 25V
  • F = 1.4
  • N = ?

  • N = 25 * 1.4
  • N = 35 Turns

For 24V output, we have 37 turns to wind in the secondary.

The good thing is that with the formula, we can calculate any voltage we want to get at the output of our switching power supply.

Components list

Semiconductor

  • U1 ......... Integrated Circuit TNY268P
  • OPT....... TLP181 Opto-Coupler
  • D1, D2 ... Diode 1N4007
  • D3 ......... Fast Diode FR307
  • D4 ......... Zener Diode *See Text

Resistor

  • R1 .... Resistor 10Ω / 1W (brown, black, black, gold)
  • R2 .... Resistor 200KΩ / 1/4W (red, black, yellow, gold)
  • R3 .... Resistor 470Ω / 1/4W (yellow, violet, brown, gold)

Capacitors

  • C1 ....... Electrolytic Capacitor 47uF/400V
  • C2 ....... Polyester Capacitor 2.2nF
  • C3 ....... Polyester Capacitor 100nF
  • C4 ....... Electrolytic Capacitor 470uF/35V

Several

  • T1 ......... EE-25 Ferrite Transformer
  • P1, P2 ... Connector WJ2EDGVC-5.08-2P
  • Others... PCI, Wires, Solders, Etc.

Printed Circuit Board - Download

In Figure 5 below, we are making the PCI available in GERBER, PDF and JPEG files, for those who want to create a more optimized assembly, either at home, or if you prefer, at a company that prints the board.
PCB-Mini Switching Power Supply 5V - 25V, 3A with TNY268

You can download the files for free from a direct link in the Download option below.

Conclusion

In conclusion, the mini switched power supply that provides a programable 5V to 25Vdc output is an excellent choice for various electronic devices. Its compact design, high efficiency, and low ripple and noise make it stand out compared to other similar products in the market. 

Its safety features, such as short-circuit protection and overvoltage protection, ensure that connected devices are protected from damage. If you are looking for a reliable and efficient power supply for your electronic devices, then this mini switched power supply is a great choice.

You can see the official post by clicking here! fvml.com.br

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!!!

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Monday, January 30, 2023

Switched Power Supply SMPS 13.8V 10A using IR2153 IC and IRF840, with PCB

Circuits to Assemble , power supply
Switched Power Supply SMPS 13.8V 10A using IR2153 IC and IRF840, with PCB
13.8V-SMPS-Power-Supply-Using-IR2153-IC-and-IRF840-Mosfet

Para Versão em Portugues, clique aqui!

Switched Power Supply SMPS 13.8V 10A using IR2153 IC and IRF840, with PCB

This circuit is a straightforward design for an SMPS power supply, utilizing the IR2153 IC. This chip, which has only 8 pins, functions as a PWM controller, enabling the creation of a high-performing and cost-effective unregulated switching power supply for basic projects. 

The output voltage of this power supply is set at 13.8V and can be adjusted via the trimpot RV1. It also provides a steady current of 10A at its output.

The Circuit

The circuit basically consists of 8 main steps:

  1. Protection Circuit: It comprises a 5A/250V fuse, which operates if there is a current greater than the fuse's breaking current.
    At the same time we also have an NTC (Negative Temperature Coefficient), it is a surge current limiter, this same topology can be found in most SMPS power supplies, such as notebook power supplies, PC power supplies, computer AT / ATX power supplies, etc.

  2. Transient Filter: This step consists of an initial capacitive filter that inhibits high frequencies from returning to the network, or vice versa, and soon after, the EMI filter coil, which serves to attenuate high frequency noise.

  3. Primary Rectification: Made up of the D1 rectifier bridge.

  4. Primary Filter: Composed of capacitors C4 and C5.

  5. Switching: Composed of a PWM generator, and the IRF840 power MOSFETS transistors.

  6. Transformer: The transformer is a high-frequency Chopper Trafo, and it performs the isolation and high-frequency transformation of the signal generated by the PWM set and switching transistors.

  7. Fast Rectification: Formed by diode D3, this is a fast and double diode, since the oscillated frequency in the circuit is quite high.

  8. Output filter: Composed of inductor L2 and capacitor C9.

Caution

This circuit works directly connected to the electrical network, this is extremely dangerous, any carelessness, or wrong connections, design error, or any other occasion, can lead to irreversible damage.

We are not responsible for any type of occurrence. If you don't have enough experience, don't build this circuit, and if you build it, when testing it, be sure to have the proper protections and be accompanied by someone else.

The PWM Circuit

The power supply for the IR2153 IC comes through a 27K 5W power-limiting resistor together with the C5 capacitor. In the internal package of this IC, there is already a 15.6V Zener diode, which stabilizes this voltage, but the current is low.

So, be careful not to put the resistor R3 with a smaller resistance, as it would increase the current at the input of the IC, and the Zener could break and consequently burn the IC.

An improved solution would be to put a 15V Zener diode to ensure voltage stabilization and IC protection, which you can be doing if you wish.

If you are using the IR2153D, there is no need to use the D2 diode which is the FR107 or BA159, as this IC already has this diode internally, if it is the IR2153 “without the letter D”, leave it as it is in the schematic, “ with diode D2”.

The complete schematic diagram is displayed just below in Figure 2, both the diagram and the materials are available for download at the link below.

Figure-2-Schematic-Diagram-SMPS-13.8V-10A-power-supply

The Transformer

The TR1 transformer was taken from a scrap ATX power supply, the model is the IE-35A, but you can be using practically any model of ATX power supply Trafo.

There is no need to rewind the transformer, just pay attention to the Pinout that we will use for the Trafo, as shown in Figure 3 below.

Fig.3-ATX-power-supply-Trafo-wire-connection-diagram

The Trafo model used was the EI-35A, but we can also use any other AT or ATX power supply that has the same standards, such as models EI-33, ER35, TM3341101QC, ERL35, EI28, etc., as shown in Figure 4 below.

Fig.4-ATX-power -supply-transformer-model-EI-35A

The L1 inductor is the same used in the ATX power supply, we removed it and didn't make any changes, and the L2 inductor, from the output EMI filter.

You can also use the AT/ATX power supply scrap, but if you want to wind your own filter, you can wind it on a Ferrite Toroidal core.

The winding must be carried out using a Toroidal core winding, with the coil using 0.6 mm super-enamelled copper wire with 25 turns.

Component List

  • Semiconductors
  • CI1 ......... Integrated Circuit IR2153D, or IR2153 (See Text)
  • Q1, Q2 ... IRF840 MOSFET transistors
  • D1 .......... KBU606 Diode Bridge (or Equivalent)
  • D2 .......... FR107 or BA159 Fast Diode (or Equivalent)
  • D3 .......... MBR3045PT Diodes Fast  (or Equivalent)

  • Resistors
  • R1, R2 .... 150KΩ resistor - (brown, green, yellow, gold)
  • R3 .......... 27KΩ 5W resistor – (red, violet, orange, gold)
  • R4 ...........8K2Ω resistor – (gray, red, red, gold)
  • R5, R6 ... 10Ω resistor – (brown, black, black, gold)
  • RV1 ....... 47kΩ trimpot 
  • NTC1..... 5Ω thermistor

  • Capacitors
  • C1, C2 ... 470nF - 400V Polyester Capacitor 
  • C3, C4 ... 330uF - 200V Electrolytic capacitor 
  • C5, C7 ... 100uF - 25V Electrolytic capacitor 
  • C6 .......... 680pF Polyester Capacitor 
  • C8 .......... 2.2uF - 400V Polyester Capacitor 
  • C9 .......... 2200uF - 25V Electrolytic capacitor 

  • Miscellaneous
  • L1, L2 .... Inductor *see text
  • TR1 ....... Transformer *see text
  • F1 .......... 5A Solderable fuse
  • Other...... Wire, Solder, Plate, Etc.

Printed Circuit Board

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.

Files to download, Direct Link:

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

You can see the official post by clicking here! fvml.com.br

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!!!
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Saturday, December 31, 2022

RJ45 Ethernet Cable Color Standard - T568A and T568B - EIA/TIA Standard

IoT , Learning
RJ45 Ethernet Cable Color Standard - T568A and T568B - EIA/TIA Standard

RJ45 Ethernet Cable Color Standard - T568A and T568B - EIA/TIA Standard

Back in the past, a few decades ago, there were no standard regulations for the wiring of structured networks in the IT industry.

The standards for these networks were decided upon by the companies or professionals responsible for installing the wired networks. 

This lack of standardization made it difficult to maintain or modify the network structures of companies, especially when done by another company or professional.

To address this issue and with the increasing growth of technology and infrastructure for wired networks, the TIA/EIA standards were developed. 

In 1991, the TIA/EIA, 568A and 568B standards were introduced by the Electronic Industries Association (EIA) and the Telecommunications Industry Association (TIA) to standardize the electrical and electronic connections of network cables and their connections. 

The 568A standard was revised in 1994 to include Category 4 and Category 5 (UTP - Unshielded Twisted Pair) wiring, and in 2001 the EIA/TIA 568-B standard was published, covering a total of 10 different categories.

T568A and T568B Categories

There are two different categories of TIA/EIA standards, commonly known as RJ45 Standard B and RJ45 Standard A, which are actually T568A and T568B. 

These are termination standards used by Internet Providers, Backbone Infrastructure, Industrial Wiring Infrastructure, and also by small businesses and residential wiring.

However, the difference between these two categories is that the orange/white and green/white pairs, which correspond to pins 1 & 2, 3 & 6, are exchanged in the assembly of the cable, as illustrated in Figure 1 below.
Fig.1-Standard-Colors-Cable-Network-RJ45-T-568A-T-568B-Standard-EIA/TIA

It is worth remembering that even with changes to the set of pairs, when the same standards are used at both ends of the cable, the results will be the same, with direct connections at their ends.

In Table 1 below, we have the configuration of the pins and their corresponding colors, following the two standards side by side for comparison.

Sequential Table of Colors and Pinning Standard T-568A and T-568B

PinT-568AT-568B
1White/GreenWhite/Orange
2Green        Orange
3White/OrangeWhite/Green
4BlueBlue 
5White/BlueWhite/Blue
6OrangeGreen
7White/BrownWhite/Brown
8BrownBrown

The T568A standard is the widely accepted standard because it is compatible with most wiring schemes and is what I recommend for most applications.

Crossover Cable

Crossover cables, use the T-568A and T-568B standards at each end as illustrated in Figure 2 below. These categories of cables are used when we need to, for example, connect two computers or laptops without using a router or switch.

Fig. 2 - Connection of Crossover Cable Standards T-568A and T-568B

It is worth remembering that if you are still using older equipment, you should not connect crossover cables between the computer and a switch or router, as in some cases it can damage the equipment.

Now if you work with newer, more modern equipment, they use AUTO MDI/MDIX technology, which automatically identifies the connected interface and even if it is of the crossover type, there is no problem, as it automatically configures itself.

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

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Monday, July 4, 2022

Automatic Programmable 4.2V Battery Charge, Current up to 500mA using LTH7R IC with PCB

Battery Charger , Circuits to Assemble
Automatic Programmable 4.2V Battery Charge, Current up to 500mA using LTH7R IC with PCB

The LTH7R IC is a constant current or constant voltage base charger chip, mainly used for single cell lithium battery charging.

No external sensing resistor is needed, it has its internal power MOSFET structure, so no external reverse diode is needed.

The LTH7R IC has under temperature protection and control, it adjusts the charging current automatically to limit high temperature on the chip.

Its charging voltage is fixed at 4.2V, and the charging current can be adjusted by an external resistor.
When the float voltage is reached and the charging current drops to 1/10 of the defined circuit, the LTH7R IC automatically completes the charging process.

When the input source voltage is removed, the LTH7R IC automatically enters low current mode, drawing less than 2uA from the battery.
When the LTH7R IC enters standby mode, the supply current is less than 25uA. The LTH7R IC can also monitor charging current, has the features of voltage detection, auto-cycle charging, and has an indicator pin to indicate end-of-charge status and input voltage status.

Features

  • Programmable charging current up to 500mA
  • No need for external MOSFET, sensing resistor, reverse diode
  • Constant current or constant voltage mode operation, with thermal protection function Preset charging voltage
  • Standby current is 20uA
  • 2.9V slow charge voltage
  • Soft start limits the inrush current
  • Adopt SOT23-5 package, application line

Product application

  • Microphone Battery
  • Light Camera
  • Mobile Phones, PDAs, MP3 players
  • Bluetooth headsets 

External programming of the load current:

PROG (pin 5): Constant current load current setting and load current monitoring terminal. The load current can be programmed by connecting an external resistor from the PROG pin to ground.

In the pre-charge phase, the voltage of this pin is modulated by 0.1V; in the constant current charging stage, the voltage of this pin is fixed at 1V.

In all charging state modes, measuring the voltage of this pin can estimate the charging current according to the following formula:

General Formula:

I_bat = 1000 / R_prog

To use, for example, in a charger whose required current is 300mA, we can use the formula as follows:
  • I_bat = 1000/ R_prog
  • R_prog = 1000 / I_bat
  • R_prog = 1000 / 300
  • R_Prog = 3.3K

To use, for example, in a charger whose current required is the maximum current, 500mA, we can use the formula as follows:
  • I_bat = 1000/ R_prog
  • R_prog = 1000 / I_bat
  • R_prog = 1000 / 500
  • R_Prog = 2K

We leave just below a small table ready with five models with the standard currents for the battery charger.

Model R_prog I_bat
1 10K 100mA
2 5K 200mA
3 3,3K 300mA
4 2,5K 400mA
5
 2K
500mA

The Circuit Schematic

In Figure 2, below, we can see the schematic diagram of the Automatic Programmable 4.2V Battery Charge, Current up to 500mA using LTH7R IC.

All circuit components are SMD, the power supply input is done by soldering on the PCB. This type of miniaturized SMD circuit is great to be implemented in circuits with small spaces.

The capacitors are SMD electrolytic, but if you have tantalum capacitors, you can put them on, it will help with the plate height, but if you can't find them, you can use electrolytic.

The charger circuit supports voltage between 4.4V to 7V, the recommended is 5V, which is great news for us to be able to charge our battery in a PC USB port or even with cell phone chargers.
Fig. 3 - Automatic Programmable 4.2V Battery Charge, Current up to 500mA using TH7R 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.
Fig. 4 - PCB Automatic Programmable 4.2V Battery Charge, Current up to 500mA using TH7R 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!!!

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Wednesday, June 22, 2022

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

Circuits to Assemble , Electronic Circuits
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!!!

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Wednesday, May 18, 2022

Electronic Resistive Load - 50A Power Supply Test with PCB

Circuits to Assemble , Electronic Circuits
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 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 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!

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