The use of solar energy will be the topic for a long time an active is used a lot in this business at one of these inverter dc to ac converters. Ac dc voltage from PV module circuit (240Vac) is turning 100 watts of power system voltage control provided by Atmel. ATmega to drive MOSFETs in the output ICL7667 ( Dual-Power MOSFET Driver) The transformer used etd34 All details about the circuit formula’s calculations also pcb circuit diagrams and drawings given ATMega8 software. Most excellent of all the floors of the circuit given in separate schemas (PV current, voltage sensing, drivers, etc.) You can use this circuit for different applications or projects can be useful in the calculations. 100W Solar Panel Inverter The Inverter Module is designed to connect a 100W PV panel directly to the 240V AC grid. The module consists of a DC-DC boost converter and a DC-AC inverter. The design focus was to totally isolate the DC-DC converter from the DC-AC inverter.

The only coupling between the two sides is the DC bus voltage. The AC side regulates the 350V bus by adjusting the average alternating current output from the module. The DC side adjusts the input terminal voltage, to track the Maximum Power Point of the PV panel. The focus of this thesis was the development of the Half Bridge Dual DC-DC converter stage. As most power loss occurs in the DC boost stage, efficiency was a major design issue. Efficiencies around 95% were aimed for. A micro-controller is used for controlling the converter, and ensuring that maximum power is transferred from the PV panel to the DC bus capacitor.

This required the development of a Maximum Power Point Tracking algorithm. The resulting prototype tracks the maximum power point of the PV panel, and transfers maximum power to the 350V bus with efficiencies above 90%. The major sources of power loss are transformer and inductor core and copper losses, and MOSFET switching and conduction losses.

Efficiency was improved by focusing on these areas. Soruce: 100Watt PV Panel Converter Atmega8 100W DC to AC ICL7667 ETD34 alternative link: alternative alternative Alternative File Download LINK list ( in TXT format).

In many circuits, it is necessary to use MOSFETs for switching. In many cases, the MOSFET drive signals are generated by microcontrollers. In other cases, they are generated by ICs – PWM controllers, timers or any IC in fact. However, MOSFETs cannot always just be connected to the drive signal and be expected to work properly. Due to the construction of the MOSFET, driving it is not the simplest of tasks, especially for beginners. There are many users who regularly ask for help on MOSFET drive related issues or problems on different blogs, websites and forums. So, here I will show some MOSFET drive techniques/methods for MOSFETs configured as low-side switches.

Another thing to remember is the gate capacitance. So, when the MOSFET is to be turned on or off, the gate must be driven high or low with sufficient current quickly enough so as to charge or discharge the gate capacitance quickly enough so that the MOSFET spends minimal time in the linear region and is quickly turned fully on or off. This is true especially for high speed switching when time period is small.

However, in low frequency applications, this may not be a big problem as, even if the MOSFET spends some time in the linear region, it will spend the (remaining) majority time fully on and thus the small amount of time spent in the linear region will not cause much of a problem. The MOSFET could be driving a DC fan that will be turned on, kept on for 2 hours and then kept off for about an hour and turned on and off in few hour intervals.

The MOSFET is driving a DC lamp that will stay on for the entire night and will only be turned off in the morning and kept off during the entire day. The MOSFET is driving a heating element through which current passes (the heater is on) for about 16 hours a day.

The MOSFET is driving an IR LED in a remote transmitter unit. The LED is turned on and off frequently – every few seconds. 2, the MOSFET turns off almost instantaneously when Vin is zero. This is because when Vin is zero, Q3 is off and Q5 is on. Q5 pulls the gate low, discharging the gate capacitance. However, the MOSFET turn-on is not instantaneous.

When Vin is high, Q3 is on and Q5 is off. So, current flows through R14 and charges the MOSFET gate. Here turn-on time is dictated by R14.

However, when I say long turn-on time, I am talking in the order of tens or hundreds of microseconds to milliseconds at max. Thus this circuit can easily be used in any of the situations depicted in the four examples above or any similar situation. This driver cannot be used when switching is done in the order of microseconds where both turn-on and turn-off must be very quick – almost instantaneous. 3, the MOSFET turns on almost instantaneously when Vin is one. When Vin is one, Q6 is on and so Q8 is on and thus VGS = +VDRIVE and so the MOSFET turns on.

However, when Vin is zero (and so Q6 and Q8 are off), the MOSFET gate discharges through R18. So, gate discharge is slow and turn-off time is dictated by R18. However, this “slow” time is in the same order as mentioned above and so can be used in any of the situations depicted in the four examples above or any similar situation.

Similarly, this driver cannot be used when switching is done in the order of microseconds where both turn-on and turn-off must be very quick – almost instantaneous. If the MOSFET is a Power MOSFET, +VDRIVE should be at least 8V. A voltage commonly used is 12V. +VDRIVE should be less than VGS(max) as specified in the MOSFET datasheet.

Some “headroom” should be used. So, if VGS(max) is specified as 20V in the MOSFET datasheet, it is good practice to use lower than 18V. 12V and 15V are commonly used for Power MOSFET gate drive. For Logic Level MOSFETs, 5V is most common because the reason a Logic Level MOSFET is usually used instead of a Power MOSFET is that the Logic Level MOSFET can be driven from 5V. In the above shown circuits, the MOSFET can be either a Logic Level MOSFET or a Power MOSFET. +VDRIVE must be selected accordingly.

You may, then, ask why a driver is needed. You may simply drive the microcontroller directly from the microcontroller. And well, you can. For low speed applications. So, in the four situations previously described, the microcontroller can directly drive the Logic Level MOSFET. The problem lies where the microcontroller output voltage will drop when supplying the current needed to quickly turn the MOSFET on and off when a large current will be required.

So, the MOSFET may not fully turn on. In that case, the driver shown in Fig. 5 can be used to ensure that the MOSFET can be driven with sufficient current.

If R28,R29 are too low (i.e. Values comparable to R23) then the resistors will cause loading of the previous stage. This will cause the voltage at bottom point of R23 to hover somewhere between 0 and V+ rail.

If this happens the output npn-pnp pair will conduct simultaneously (in linear mode) and cause heating up and possible burn-out of the pair. On the other hand using excessively high values will cause a problem with the switching of the MOS gate, because the maximum available output current from the npn-pnp pair will be lesser (lesser maximum base current available etc.).

With R28,R29 values of 10K and R22 of 4K7 with off-the-shelf npn and pnp transistors (BC547,BC557) the rise/fall times at the output MOS gate is around 250nS for 3A load and 6V supply, for a IRFZ44N MOSFET. This means that it should be useable to upto around 1kHz (rise/fall time. For simplicity's sake it has been considered that VBE = 0.7V but you must keep in mind that this is a property of the transistor and may vary depending on the transistor, although it should usually be around 0.7V (or 0.6V). At certain voltages, it may cause problem. But, the input shouldn't ever be 0.7V since it will come from an IC or microcontroller, whose output when high is never 0.7V but nearer the supply voltage, due to which this problem is never faced practically. And that is why, this circuit is accepted and also used in many commercial circuits, even in India. Thanks Tahmid for your reply.

I got my problem. It was nothing but the ground reference.

I tied both battery positive and solar positive together and tried to switch on ground lines. Battery connected to the mosfet drain and solar connected to the source. As driving for 12V system both voltage level are same but when driving for 24 volts there's the problem because I supplied the drive power from 12V battery with ground from battery. Now I drive mosfet gate with reference to solar ground and no problem. I will upload the circuit very soon. Thanks you guys again.

Mosfet Driver Circuit Design

Anonymous What is the purpose of having 10k resistors to pull down mosfet driver input? Are they required? Also may I ask what kind of resistors and values you are using between mosfet driver and mosfet gate? I see on schematic you posted 10 ohm resistor, but how you found that particular value?

Sorry, one more question if you don't mind: what kind of capacitors can be used for decoupling mosfet driver? Some datasheet propose film capacitors but MKP types are rated for much higher voltages and are big, can I use tantalum capacitor here? (I'm trying to use smd components). The 10k pull down resistors have been used to ensure that no input pin is floating, so thatstray noise is not picked up. For the gate resistance, usually values between 4.7 ohm and 22 ohm can be used. 10 ohms is a common value that can work.

For high frequencies (100kHz and above), you may need to reduce that to about 6.8 ohms. For more detail regarding the gate resistance, refer to this: For low capacitance (eg 100nF) decoupling capacitors, ceramic types are the best. Try to use ceramic disc capacitors instead of tantalum capacitors. You should be able to easily get 50V ceramic disc capacitors. Like these: Hope this helps. Regards, Tahmid.

L Young Hello Tahmid I have been following your tutorial all along even in other forums. I am trying to build a 1000 watt inverter to run my fridge but having great problems. I built fig 5 as my driver for irfz44 fets in my dc to dc converter but as u say u need about 8v to fully turn on the fets. I want to know if I should have this voltage on the gate of the fets when there is no load on the output of the h bridge. Please clearlt tell me if this voltage should be there at all times. This is my question I have been trying to get an answer for for the past two months. Remember that the circuits shown here are for low-side MOSFET drive and so should not be used for H-bridge drive unless you're using them for driving the low-side MOSFETs in the H-bridge.

To drive the MOSFET fully on (with or without load), the gate of the MOFSET should be at least about 8V higher than the source. However, if you don't have a load, the circuit is incomplete and it doesn't matter if the MOSFET is on or off. But, considering that a load may be applied at any time, since it's an inverter, the voltage on the gate must be present whenever the MOSFET is to be on. I hope that answers your question. Regards, Tahmid. Hello Tahmid.

I am using the TC427 to drive the low side N-mosfet from H-bridge. The P-mosfet from high side is on. (I am only testing one direction of the bridge) When I start, stop the motor the TC427 burned.

Now I am using the 4 diodes in the H-bridge and the new TC I use is alive. It is so easy to burn them?

The P-mos is IRF4905, the N-mos is IRF3205. I will design a high bridge and I am afraid that the TC will get burned easy. What may be the cause? If you could let me some mail I can send you the circuit. There needs to be a minimum collector current flowing to ensure proper operation of the transistor and to get 0V at collector when Vin = 5V. The collector current must be greater than ICEO (specified in the datasheet). So this means that you can't pick a resistance (for R23) too close to the resistor of the CE junction, let alone higher.

In fact it should be at least 10 times less in order to ensure proper operation. Of course this 10 times isn't a hard set rule, but something you can do to avoid problems. Anonymous Hi i checked the circuit in fig.4 but in order to switch the mosfet fast ' 60nS 'like irlr2905 we need a high current going through the bjt. With R23 1K and supply of 12V we have 0.012A going to the bjt pair.

Does the 0.012A open the irlr2905 fast??? We simulated with r23 160Ohm for 0.075A collector current and R28 R29 500Ohms and on sim it get 50nS to for the Voltage across irlr2905 to go from 24 to 0V, but it takes 500ns for the Vgs to go from 200mV to 12V or 300ns to go from 200mV to 10V. Are the values i selected for R23, R28 and R29 correct??? Hi tahmid i am working on two switch buck-bost converter.

I am using irfp460 power mosfet.This converter requires the use of two active switches and is designed by combining a buck converter and boost converter design in the same topology. Due to this design this converter can work as Buck-only, Boost-only or Buck-Boost converter. The input voltage source is connected in parallel with diode D1, MOSFET Sboost, load capacitor, C. MOSFET Sbuck is connected between the input voltage source and diode D1. The inductor is connected between D1 and Sboost, while D2 is connected between Sboost and the output or load capacitor. Please tell me which side of gate driver i use for sboost and sbuck.

Also tell me about optocoupler hcpl-3120. I am Syed Tahmid Mahbub, from Dhaka, Bangladesh, born on August 1, 1994. Electronics is my passion and from class V, I have been learning electronics. I learnt and worked mostly on SMPS, power electronics, microcontrollers and integration of microcontrollers with SMPS and power electronics.

I've used PIC and AVR microcontrollers - PIC 10F, 12F, 16F, 18F, 24F, dsPIC 30F, 33F, PIC32, ATmega and ATtiny, integrating them with various SMPS and power electronics circuits. I have completed my Bachelor's degree from Cornell University (Class of 2017) in Ithaca, New York, USA, majoring in Electrical and Computer Engineering (ECE). I am a member of the forum www.edaboard.com, where I am an 'Advanced Member Level 5' (the highest level attainable) and also the forum allaboutcircuits.com, where I am a 'Senior Member'. I post to help solve electronics-related problems of engineers and engineering students from all over the world. I love watching and playing cricket and football (soccer), and listening to music. I am now a hardware engineer at Apple in Silicon Valley, California, USA.