---
title: Select a Gate Driver IC
---
# Select a Gate Driver IC
When I first designed a class-D amplifier, it was a nightmare to find a gate driver I need. There were so many types and I didn't even know how to choose one.

This article is a note for anyone who is trying to find a suitable gate driver. It aims to give clear steps to help select a gate driver IC.
## Step 1: Know the input/output
The first thing, know what input you have and what you want to deliver at the output side. Is it a half-bridge, full-bridge or three-phase? Do you need isolation?
## Step 2: Voltage Rating
1. __1.5 ~ 3 times__ larger than the operating voltage
2. Read the datasheet of your MOSFET or IGBT to check the operating voltage
## Step 3: Drive Current Matters
1. The required gate charge to raise gate voltage to the desired level.
2. After knowing how much charge we need, next thing is to choose drive current according to the rise and fall time targeting. Use formula
\begin{align}
Q_{Gate}=I\times t
\end{align}
5. Usually, it is not easy to find a gate driver with exact figure. Choose one with higher rating and then attach gate resistor to limit source and sink current.

## Step 4: What's next? External Components
With the criteria above, the options should be narrowed down. However, it is not the end. The selectrion of external compnonents are important as well.
### Bootstrap Capacitor
It should stored charge about __50 times__ more than the gate charge at the operating voltage
The formula to calculate is
\begin{align}
Q_{Gate}=C_{Bootstrap}\times V_{Bootstrap}
\end{align}
\begin{align}
Q_{Required}=Q_{Gate} \times 50
\end{align}
:::warning
:point_right: Choose low ESR capacitors
:::
:::warning
:point_right: Usually, bootstrap circuit also comes with a diode and a resistor.

A diode is to prevent inverse current (discharge) from the bootstrap capacitor.

A resistor is to limit inrush current when system is first powered up. $(I = C\frac{dV}{dt})$ It could damage the diode.
:::

## Reference
1. [Selecting-Gate-Driver-Tutorial](https://www.mouser.com/pdfdocs/Selecting-Gate-Driver-Tutorial.pdf)
2. [High and Low Side Driver vs. Half-Bridge Driver](https://electronics.stackexchange.com/questions/106469/high-and-low-side-driver-vs-half-bridge-driver)
3. [Webinar: Gate Driver Principles, Considerations and Selection Process](https://www.youtube.com/watch?v=L93ookZsh6s&ab_channel=SemikronDanfoss)