Compact 3A Mini Switching Power Supply: Build Your Own 5V-25V Solution with TNY268 and PCB

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:

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.

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.

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:

The calculation for an output voltage of 9V:

The calculation for an output voltage of 12V:

The calculation for an output voltage of 24V:

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

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.

• Click Here!

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.

13.8V-SMPS-Power-Supply-Using-IR2153-IC-and-IRF840-Mosfet

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:

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

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

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

Effortless Battery Charging: Build an Automatic Programmable 4.2V Charger with up to 500mA Current Using LTH7R IC and 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.

Fig. 2 - Pinout LTH7R IC

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 3, 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 4, 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

I hope you enjoyed it!!!

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!!!

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

I hope you enjoyed it!!!

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!!!

The circuit

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

Fig. FM Transmitter 75 to 108MHz using BA1404 IC with PCB

Build Your Own FM Transmitter: Step-by-Step Guide with BA1404 IC & PCB

This is a Stereo FM Transmitter, based on the BA1404 Hi-Fi Integrated Circuit, which is a stereo FM modulator that creates composite stereo signals, with low consumption, maximum 3mA, and an operating voltage between 1.5 to 2V.

The FM modulator has carriers in the FM transmission band (75~108MHz). It develops signals composed of a MAIN signal (L+R), a SUB signal (L-R) and a pilot signal (19KHz) using 38KHz crystal oscillators.

Feature

• Available in DIP18 and SOP18 packages
• Low operating voltage range (1.0V ~ 2V)
• Low power consumption, typically 3mA
• Requires few external components

Applications

• FM stereo Transmitters
• Wireless Microphones
• FM PLL Oscillator 
  

ATTENTION!

For each Country, Region, State... There are Laws on broadcasting, telecommunications, audio and video transmission, etc.

Do not use telecommunications equipment without authorization from the entities responsible for transmitting Radio Frequencies.

Electronic Circuits teaches electronics applied to various segments, with the aim of improving knowledge, we do not support or take responsibility for any type of illegal operation.

For any operation with RF, we recommend looking for the competent regulatory agencies, seeking certification and/or legalization.

You might also be interested in:

• FM Transmitter 70MHz to 150MHz using MAX2606 IC with PCB
• 2.5KM FM transmitter, using transistor 2N3866 with PCB
  

The transmitter circuit

The schematic diagram of the FM Transmitter 75 to 108MHz using BA1404 IC, 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 - Diagram Schematic FM Transmitter 75 to 108MHz using BA1404 IC

The Coil

The L1 coil is a Model 750A3.5T Inductor, however, you can make your own inductor by winding 3 to 4 turns of 24 AWG copper wire, or 0.5 mm diameter copper wire, into a 5 mm diameter ferrite core.

The Antenna

The antenna can be used with a telescopic antenna purchased at electronics stores, if you don't have it, you can use approximately 30cm of rigid wire, which will work perfectly.

Component List

• Semiconductors
• CI1 ...... BA1404 Integrated Circuit
  
• Resistors
• R1, R2 .... 47KΩ resistor (yellow, violet, orange, gold)
• R3 ........... 270Ω resistor (red, violet, brown, gold)
• R4 ........... 150KΩ resistor (brown, yellow, green, gold)
• R5 ........... 5.6KΩ resistor (green, blue, red, gold)
• R6, R7 .... 27KΩ resistor (red, violet, orange, gold)
  
• Capacitors
• C1, C2, C6, C12, C13 .. 1nF Ceramic Capacitor
• C3, C4, C5, C14 .......... 10uF 16V Electrolytic Capacitor
• C7, C10 ....................... 10pF Ceramic Capacitor
• C8, C9, C11 ................. 15pF Ceramic Capacitor
• C15 .............................. 220pF Ceramic Capacitor
  
• Inductor
• L1 ......... 750A3.5T Inductor *see text
  
• Cristal
• CR1 ...... 38KHz Cristal
  

• Miscellaneous
• P1, P2 .... Screw Terminal Type 5mm 2-Pin Connector
• ANT1 .... Telescopic Antenna *See Text
• Others .... Printed Circuit Board, 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 FM Transmitter 75 to 108MHz using BA1404 IC

Files to download, Direct Link:

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

I hope you enjoyed it!!!

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!

ATTENTION!

You might also be interested in:

• FM Transmitter 70MHz to 150MHz using MAX2606 IC with PCB
• FM Transmitter 75 to 108MHz using BA1404 IC with PCB
  

Characteristics!

• High sensitivity of audio pickup
• 12V to 16Vdc supply voltage
• Simple circuit to assemble
• Great range, about 2.5km
• Easy assembly
  

The transmitter frequency adjustment, is regulated through the CV1 trimmer, and the CV2 and CV3 trimmers, to regulate the antenna impedance matching, must be done with patience for a better use.

The coil L1, L2 and L3 must be made with enameled wire 22 AWG of 1 cm in diameter with air core, the number of turns is described in the component list.

L4 is a 10uH RF shock, and you could be building your own RF shock by winding 15 vols of thin enamel wire around a 1MΩ resistor, soldering to both ends of the copper wire, at each end of the resistor.

The antenna can be a length of rigid wire between 20 and 50 cm for short ranges, or use a 1/2 wave dipole antenna for long ranges.

The Power Supply

PCB - 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 - 2.5KM FM transmitter, using transistor 2N3866

Files to download, Direct Link:

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