H-Bridge diode and ESD diode

[cmy1st]

Hello!!

I have question for H-Bridge diode
This is H-Brige diode


When i design H-Bridge, i know H-Bridge need diode for below reason



" If the switch opens suddenly, then the current wants to go to zero quickly and dI/dt would be a large negative value. Since the motor is an inductor and V=LdI/dt, the voltage across the motor hass a large negative value. we could have voltage spikes. These voltage spikes can cause the switch to arc over and blow up.

The solution to this problem is to putwhat is known as a flyback diode in the reverse direction across the inductive load, so that the voltage spike will forward bias the diode, creating a return path for the current."

But I have ESD diode in chip at H-Bridge diode output pin , this ESD diode has same connection like flyback diode

So, i confuse What differet flyback diode, and ESD..

and I really need flyback diode parallel to ESD

Thanks.

 

[crutschow]

Typically, unless the load inductance is high, the parasitic diode in a MOSFET can operate as the flyback diode in a H-bridge so you don't have to add separate diodes.

Note that ESD (Electro Static Discharge caused by static generation) is different from the inductive current spike caused by an inductor.

 

[cmy1st]

but I have high inductance(almost 140uH), high current(90mA)

then, It need separated diode??

and You say "ESD is difference from H-Bridge inductor current"

then another diode is required for flyback?