Passive PFC Circuit for 250W PC Power Supply

The circuit show here is input circuitry of the power supply with passive PFC. Note the line voltage range switch connected to the center tap of the PFC inductor. In the 230V position (switch Open) both halves of the inductor winding are used and the rectifier functions as a full wave bridge. in the 115V ( switch closed) position only the left half of the inductor and left half of the rectifier bridge are used, placing the circuit in the half wave double mode. As in the case of the full wave rectifier with 230V AC input, this produces 325V DC at the output of the rectifier. This 325 VDC bus is , of course, unregulated and move up and down with i9nput line voltage.

Circuit Courtesy


The AC-DC power stage is shown in Figure 6. The connection port is set up identical to the ECM motor controller port for ease of testing. The common is the output port for the control signal 24-V AC inputs. The other input/output ports are for the hot, neutral, and earth ground connections. This TI Design also incorporates a 15-A 250-V AC rated fuse to prevent damage to the board in case of overcurrent. The RV1 metal oxide varistor (MOV), rated for 275-VRMS, is also used for surge protection. Both 499-kO resistors are used as the discharge resistive network for capacitors C5 and C6, and are rated for 400 V. The rectification bridge is rated for 200 V at 35 A, leaving plenty of room for a sufficient safety
factor. L2 is a common-mode filter. To limit the inrush current of the bulk DC capacitors, an inrush current limiter RT1 is provided. D4 is the full bridge rectifier. L1 is the DC choke provided for meeting the line harmonic standard. C7 is the electrolytic capacitor at the DC bus. The AC-DC subsection of the design has been designed with the DC bus capacitor and necessary filters for conducted emission, surge, and EFT protection as per the standard EN55014. Figure 7 shows the simulation output of the design using the listed circuit parameters.To reduce the voltage ripple of the DC output, calculate the bulk capacitor or DC link capacitor value. This helps ensure that a sufficient hold up time is provided, during which the regulated supply continues to provide the regulated voltage output in the event of a short lapse in AC voltage supply. The following arithmetic is used to properly fit the circuit with an appropriately sized DC bus capacitor.



Power Supply For Ultra High-Fidelity Audio Amplifier LME49810, LME49811, LME49830

This application note will cover the design of a ±72V unregulated power supply designed specifically for the LME49810, LME49811 and LME49830 high-fidelity audio amplifier modules. The output power of the modules are approximately 220W to 250W into 8Ω and 350W to 400W into 4Ω. Complete documentation for the amplifier modules can be found in the documents listed below. AN-1625 LME49810TB Ultra-High Fidelity, High-Power Amplifier Reference Design AN-1850 LME49830TB Ultra-High Fidelity, High-Power Amplifier Reference Design Although the power supply design is specific to the amplifier modules the concepts and circuit design may be used for any power supply purpose. The power supply is an unregulated design with an option to allow connection to either 120V or 240V mains. The design uses toroidal transformers, a fully integrated bridge, and various rail capacitors for ripple voltage reduction, noise suppression, and to act as high current reservoirs. Additional circuitry to control inrush current on power up and power up/ down Mute control are also included. A complete schematic, PCB views, and Bill of Materials are provided for the power supply design.

Texas Instrument Applications Down Load



900W PFC Circuit

This PFC circuit is designed using Power Integration’s HiperPFS PFS729EG integrated PFC controller. This design is rated for a continuous output power of 900 W and provides a regulated output voltage of 380 VDC nominal maintaining a high input power factor and overall efficiency from light load to full load.

4.1 Input EMI Filtering and Rectifier

Fuse F1 provides protection to the circuit and isolates it from the AC supply in case of a fault. Diode bridge BR1 rectifies the AC input. Capacitors C1, C2, C3, and C4 together with inductors L1, L2 and L3 form the EMI filter reducing the common mode and differential mode noise. Resistors R1, R2 and CAPZero, IC U1 are required to discharge the EMI filter capacitors once the circuit is disconnected. High frequency decoupling capacitor C5 after the bridge reduces the loop area of the high frequency loop and helps reduce the noise coupled into the input wires. Resistor R3 connected in series with capacitor C1 provides damping. Metal Oxide Varistor RV1 is placed across AC power lines to provide differential mode surge protection.

4.2 PFS729EG Boost Converter

The boost converter stage consists of inductor L4, diode rectifier D2 and the PFS729EG IC U2. This converter stage works as a variable frequency continuous conduction mode boost converter and controls the input current of the power supply while simultaneously regulating the output DC voltage. Diode D1 prevents a resonant buildup of output voltage at start-up by bypassing inductor L4 while simultaneously charging output capacitor C13. Thermistor RT1 limits the inrush current of the circuit at start-up. In higher performance (efficiency) power supplies, this thermistor is shorted after start-up using a relay. Efficiency measurements should therefore be taken with RT1 shorted to obtain maximumefficiency data. Capacitors C11 and C12 are used for reducing the loop length and area of the output circuit to reduce EMI and overshoot of the voltage across the drain and source of the MOSFET inside U2 at each switching instant.

4.3 Bias Supply Regulator

The PFS729EG IC requires a regulated supply of 12 V for operation. Should this supply exceed 13.4 V, the IC could be damaged. Resistors R7, R8, R9, Zener diode VR1, and transistor Q1 form a shunt regulator that prevents the supply voltage to IC U2 from exceeding 12 V. Capacitors C6, C7 and C8 filter the supply voltage to ensure reliable operation of IC U2. Diode D3 protects the circuit against accidental reversal of polarity of the bias supply.

4.4 Input Feed Forward Sense Circuit

The input voltage of the power supply is sensed by the IC U2 using resistors R4, R5 and R6. The capacitor C9 filters any noise on this signal.


Circuit From

65W Laptop Power Adapter Circuit Diagram

The schematic in Figure 1 depicts a notebook adapter power supply employing the Power Integrations® TOPSwitch®-HX TOP258EN off-line switcher in a fl yback configuration. This power supply operates from a universal input to provide a 19 V, 65  output capable of operation in a sealed enclosure at an ambient temperature of up to 40 °C. The TOP258EN (U1) has an integrated 700 V MOSFET and a multi-mode controller to regulate output by adjusting the MOSFET duty cycles, in response to current fed into the Control (C) pin. The Eco Smart® function in U1 provides constant efficiency over an entire load range. Using a proprietary multi-cycle-modulation (MCM) function eliminates the need for special operating modes triggered at specific  loads and operating conditions, optimizing performance for existing and emerging energy-efficiency regulations. Fuse F1 provides protection to the rest of the circuit from catastrophic failures. Common-mode inductors L3 and L4 provide line fi ltering. X-capacitor C1 provides differential fi ltering, and resistors R1 and R2 provide safety from shock upon AC removal. Bridge rectifi er D1 rectifies the AC input, and bulk capacitor C2 fi lters the DC. Y-capacitor C11, connected between the transformer (T1) primary and secondary side provides common-mode filtering.




Circuit From

NTC For Power Supply

NTC Thermistor devices are made of a specially formulated metal oxide ceramic material which is capable of suppressing high current surges. TP type NTC devices, being of relatively high resistance, shall limit the inrush current for 1~2 seconds during which time the device decreases in resistance substantially to a point where its voltage drop is negligible. The devices are especially useful in power supplies (see FigA) because of the extremely low impedance of the capacitor being charged, of which the bridge is usually subjected to an exceedingly high current surge at turn-on point. NTC Thermistor of Inrush Current Limiting High inrush

As shown in Fig. , the current surge can be eliminated by Placing a NTC thermistor in series with a filament string. Yet, if the resistance of one NTC thermistor does not provide sufficient inrush current limiting functions for your application, two or more may be used in series or in separate legs of the supply circuit (Fig.A). Be noticed, the thermistor cannot be used in parallel since one unit will tend to conduct nearly all the current available. Thus, thermistor may be used in the AC (point A1 or A2) or the DC(point D1 or D2) locations in the circuit.(See Fig. A) The resistance of NTC thermistor is designed higher than the total resistance of filaments when the circuit is turned on. As current begins flowing, the thermistor shall immediately self-heat . Then, in 1~2 seconds, its resistance will be reduced to a minimum and become insignificant to the total resistance of a circuit. With the same concept, current surges in electric motors can be held to minimum. Fig. C shows a typical DC motor s turn on surge before and after the application of a TP type thermistor to the circuit.


Details From WMEC Application


Chotu A Mini Robot Chassis


CHOTU is an innovative small robot, built for hobby purpose. It’s an open metal frame architecture which holds 2 geared DC motors driving a 72mm wheels It’s a two wheel design with a freewheeling front caster ball.. This kit includes all parts needed to assemble the chassis. This project is easy way to learn real-world engineering skills, its great option for first time robot-builders.

Dimensions:  Width 110mm X Length 155mm X Height 72mm,


  • Motor Speed 120 RPM Approx.
  • Wheel Diameter 72MM
  • Screws 4 NOs for Motor M3X25mm with Nuts
  • Snap Fit On/OFF Switch
  • Screws 4Nos 3MX 10mm for PCB Or Acrylic
  • Caster Diameter 29mm
  • Chassis has facility to Mount AAX4 Battery Holder ( Battery Holder Sold Separately)
  • Quarter Pin 3MMX45MM
  • Chassis Weight 125grms
  • Two Wheels Weight 40 Grms




4 Wheel Drive Power Full DIY Robot Aluminum Chassis

This is a  Power full robot for Hobby and professional use, Its   4 wheel drive,  4 numbers of 12V 120 RPM DC motors, Robot works with PS2 wireless remote, also can be use with Futaba RC Remote with longer range. Can be use as defense, subservience purpose , duct cleaning.

  • Aluminum 4WD Chassis
  • 6x AA Battery Holder
  • 4x 12V DC Gear Motors
  • 4x 100 mm Wheels
  • DC Motor Connect Cable
  • PS2 Wireless Remote
  • PS2 Receiver with inbuilt cables
  • Micro-Controller Based Motor driver








3Amps DC Motor Speed & Direction Controller Using LMD18201 & 555 Timer

The circuit shown here are a DC Motor Speed and Direction Controller. Driver can handle DC Motor Load Up to 3Amp and DC supply 12V to 48V DC, The board is based on LMD18200 which is H-Bridge driver & 555 Timer IC generate PWM signal for speed control. Slide provided for direction Control. PWM duty cycle 10% 95%.

The LMD18201 is a 3A H-Bridge designed for motion control applications. The device is built using a multi- Shorted Load Protection technology process which combines bipolar and Internal Charge Pump with External Bootstrap CMOS control circuitry with DMOS power devices on Capability the same monolithic structure. The H-Bridge configuration is ideal for driving DC and stepper motors. The LMD18201 accommodates peak output currents up to 6A.

  • Motor Supply 12V 48V DC
  • Motor Load 3Amp 12V 48V DC
  • Logic Supply 5V DC
  • SW1 : Slide Switch To Change the Motor Direction CW/CCW
  • Duty Cycle 10% To 95%
  • Frequency 5Khz Approx.
  • Potentiometer Speed Adjust
  • LED Power Indicator

Note : J1 Jumper Close For Normal Operation.


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