The gate-driver circuit is often included in the same package as the optocoupler, so two separate optocoupler-gate-driver ICs are commonly required to complete the isolated half bridge-increasing the physical solution size.
HALF BRIDGE MOSFET DRIVER DRIVERS
Optocoupler Gate DriverĪnother approach, shown in Figure 2, avoids the problems of high-side to low-side interactions by using two optocouplers and two gate drivers to establish galvanic isolation between the outputs.
HALF BRIDGE MOSFET DRIVER DRIVER
When this happens, the high-side driver can latch up and become permanently damaged.
![half-bridge mosfet driver half-bridge mosfet driver](http://tefatronix.g6.cz/images/hbmini_schem.png)
Parasitic inductance in the circuit can cause the output voltage, V S, to go below ground during a low-side switching event. Another concern is that high-voltage gate drivers do not have galvanic isolation instead, they rely on the IC’s junction isolation to separate the high-side drive voltage from the low-side drive voltage. A potential drawback of this circuit is that the single isolated input channel relies on the high-voltage driver circuit for the needed channel-to-channel timing match, as well as the required dead time. High-voltage half-bridge gate driver.Īs shown, a conventional approach to implementing this function uses an optocoupler for isolation, followed by a high-voltage gate-driver IC. For accuracy and efficiency, the high- and low-side drivers need very closely matched timing characteristics in order to reduce the dead time when one switch of the half bridge turns off before the second switch turns on. The drivers must have low output impedance, to reduce conduction losses, and fast switching-to reduce switching losses. This article will discuss details of these design concepts to illustrate the ability of isolated half-bridge gate driver ICs to provide high performance in a small package.Ī basic half-bridge driver with optocoupler isolation, shown in Figure 1, controls output power by driving the gates of high- and low-side N-channel MOSFETs (or IGBTs) with signals of opposite polarity. Many applications, ranging from isolated dc-to-dc power supply modules that call for high power density and efficiency, to solar inverters, where high isolation voltage and long-term reliability are critical, use isolated half-bridge gate drivers to control large amounts of power.
![half-bridge mosfet driver half-bridge mosfet driver](http://www.next.gr/uploads/5/DRIVERMOSFET.jpg)
Implementing an Isolated Half-Bridge Gate Driver