IR2184 - Half bridge synchronous driver application circuit - #71

What is the IR2184 and How Does It Work?

Overview of the IR2184

• The IR2184 is an integrated driver designed for driving half bridges, specifically a synchronous driver.

• Unlike traditional half-bridge drivers that require two PWM signals (one for each MOSFET), the IR2184 operates with a single input PWM signal to control both the upper and lower MOSFETs synchronously.

Advantages of Synchronous Driving

• The integrated design offers benefits such as cross conduction control, preventing both MOSFETs from being activated simultaneously through internal circuitry.

• Key specifications include operation up to 300kHz frequency, driving currents of +1.4A and -1.8A, and a fixed internal dead time of 500 ns.

Testing the Performance of the IR2184

Circuit Setup

• The speaker plans to test the performance by assembling a circuit on a breadboard according to the datasheet's specifications.

• The chosen MOSFET for testing is the IRF510, noted for its fast switching capabilities and recovery time of only 100 ns.

Initial Testing Phase

• After setting up, waveforms are observed on an oscilloscope at a frequency of 150kHz with a duty cycle of 50%.

• Adjusting the duty cycle shows corresponding changes in voltage on the switching node, confirming proper functionality.

Analyzing Gate Signals and Dead Time

Gate Signal Observations

• Probes connected to gate signals reveal that high (yellow probe) and low (blue probe) gate signals are perfectly in phase with minimal dead time.

• Increasing duty results in synchronous switching between high and low gate signals; decreasing duty causes opposite behavior.

Measuring Dead Time

• Measurement indicates dead time aligns with datasheet claims at approximately 500 ns per division, confirming symmetrical behavior across both gate signals.

Performance Evaluation of MOSFET

Gate Charge Analysis

• Observations show that after connecting probes around a gate resistor (22 Ohm), both charge and discharge times for the MOSFET are rapid—approximately 150 ns each.