Simple H-Bridge Inverter Circuit using IR2184 ICs

In this post we will try to understand this full bridge or H-bridge inverter circuit using IR2184 ICs. Let us begin breaking it down section by section.

If you do not want to read the full article, you can simply watch the following video instead:

What This Circuit is Doing:

So here basically we are using two IR2184 ICs for driving two half-bridge stages which finally together become a full H-bridge inverter.

This inverter is converting 220V DC into 220V AC (pure square wave) across the load, using 4 MOSFETs. We are also giving 50 Hz square wave input at the left side, to run the thing with proper switching.

Input Side – 50Hz Square Wave and Toggling:

So now if we see the extreme left side, a 50Hz frequency is fed to the "IN" pin of the left half bridge IC IR2184, which is switching the IC output ON/OFF according to the 50Hz square wave signal. That 50Hz signal is coming from some oscillator, maybe from Arduino or IC 555 or anything similar.

• The 50Hz signal goes through the IC and then is terminated across the high side and low side MOSFETs, for switching them alternately.
• This IC has internal high current driver stages which works like a buffer or switch, and it helps to switch the MOSFETs efficiently through bootstrap network, even for high power loads.

We can see the SD pin of IR2184 is connected through a resistor to the VCC supply rail. This SD pin makes sure that the half bridge ICs work only as long as this pin is "high", and if a "low" is detected then this SD pin shuts down the associated IC internally, preventing an overload or over-voltage situations.

The Dual IR2184 Half Bridge Drivers:

Now let us see both the IR2184 chips:

Each IR2184 is getting supply from +12V and has a bootstrap diode (BA159) and bootstrap capacitor (10uF/25V) between VB and VS pins. This is needed to drive high-side MOSFETs properly.

The IN pin is getting ON/OFF pulses from the square wave toggle stage.

The LO pin is directly driving the low-side MOSFET.

The HO pin is driving the high-side MOSFET through the bootstrap.

Each IR2184 drives one half-bridge, so two of them together make a full bridge.

H- bridge Configuration for Single Output Oscillators like 555, 4060 etc.

H- bridge Configuration for Dual Output Oscillators like SG3525, 4047 etc.

MOSFET H-Bridge Section:

So we see four MOSFETs (shown in green color), forming the main H-bridge power stage.

Each half-bridge has one upper (high-side) and one lower (low-side) MOSFET. These are switched alternately to push-pull the load and make it feel like AC across the output terminals.

The MOSFET gates are configured with pull-down 1k resistors, which ensures that the gates of respective MOSFETs never stays floating under any circumstances, and thus avoids any spurious switching of the devices and unpredictable behavior of the MOSFETs. We also see 10-ohm series resistors at the gate lines to avoid ringing or spikes.

Across the output (LOAD), we see two 1uF/1kV capacitors, which help to kill spikes and filter some noise.

Load and Feedback Section:

Now across the output load, we see one 100k resistor and 1N4148 diode, and a preset + transistor feedback system.

This section is doing over-voltage sensing or maybe output waveform shaping. When output goes higher than expected, then voltage reaches the preset section.

This bias turns ON the relevant BC547 transistor which then pulls the SD pin of the IR2184 low, stopping one driver and balancing the output.

There's another similar feedback network configured across the Rx resistor, which is a current sensing resistor. This feedback involving the Rx resistor protects the circuit from over current, or overload situations. During such situations, the over current passing through Rx, causes an equivalent voltage drop across Rx, turning ON the associated BC547 BJT, which in turn grounds the relevant SD pin of the IC causing an instantaneous shut down of the inverter, allowing the current to get controlled below the maximum unsafe threshold.

This feedback makes the system safe, so nothing burns.

Power Supply Arrangement:

The main high-voltage DC, around 220V DC, is given to the drains of the upper MOSFETs. This is coming from a DC source, maybe from a rectified and filtered 220V AC mains.

The +12V is given separately for IR2184 and for bootstrap working. A 100uF capacitor is placed at the +12V side for good decoupling.

Important Things to Note:

Difference between IR2184 ICs and other H-bridge Drivers like IR2110

The best feature of IR2184 half bridge IC is that it uses a single input for driving its two output N-channel output MOSFETs through bootstrapping network. Meaning, it does not depend on two inputs HIN/LIN pins for the switching operation, rather uses a single "IN" pin to operate via a single frequency source.

That means, when this IC is configured as an H-bridge driver, the two half bridge modules can be directly driven or configured through standard oscillator ICs like, IC 555, UJT, IC 4060, CMOS oscillators, IC SG3525, IC 4047, TL494, TL497, or even directly through any BJT based astable multivibrator circuit.

Working Summary:

• We give an alternate 50Hz square wave to the input "IN" pins of each ICs, and that toggles which IR2184 stays ON at a time.
• Each IR2184 drives one half bridge using its HO and LO pins.
• Four MOSFETs work together to push-pull the high voltage DC across the load.
• The output becomes AC-like square wave, suitable for driving transformer-less AC loads.
• Feedback through Rx + BC547 helps protect against overvoltage and over current.
• The best thing about this IR2184 half bridge ICs is, these can be directly configured or interfaced with standard oscillator ICs such as SG3525, IC 4047, TL494, TL497, BJT astables etc.