[General] Which tiny microcontroller supports more than 20Mhz by inbuilt crytal????

[chandresha1]

I have application in which i wanted to drive full-bridge class-D amplifier. In order to control turn-on and turn-off time of Mosfet driver i have to generate two simultaneous pulse within 20ns from microcontroller. I have limitation with PCB size therefore i have to use Tiny microcontroller. As of now i have found ATtiny 24A. But the problem is it supports only 8Mhz in built crystal speed. But to generate two pulses within 20ns i need microontroller with very high-speed. So can anyone give me a suggestion what should i do???

 

[paulfjujo]

hello

But to generate two pulses within 20ns

so you need more than 50MHz as FOSC ...
You can't do it...
Even with only hardware device (no software!) and very high speed devices, maybe..

Are you sure you need 20nS , not 20µS

 

[chandresha1]

Actually my goal is to generate Hamming wave signals in order to drive piezo-electric sensor. Therefore first i have to generate square wave signal of different duty cycle and then those signals will be amplified by Class-D amplifier and after that it will be passed through low-pass filter to achieve analog signals.

The problem is in full-wave class-D amplifier. I have attached the configuration of amplifier. It has two mosfet driver to drive four Mosfet. Mosfet driver-1 will switch on mosfet-1 and 3 for first pulse to generate positive half-cycle and mosfet driver-2 will turn on mosfet-2 and 4 for second pulse to generate negetive half cycle.

I am facing problems in switching. When i give first pulse to driver-1 it will be tuned on. when i give second pulse to driver-2 it will be turned of and at the same time driver-1 will be switched off. Because of turn-on and turn-off time of mosfet and mosfet driver, there comes a moment when all the four mosfet are turned-on which results in bypass of load and positive supply direct connects to ground. This is unwanted and i want to avoid it by suitable programming of pulse timing. Therefore i need microcontroller with very high speed.

Do you have any other idea for same application? It would be really helpful to me.

 

[Dan Mills]

There are plenty of gate driver chips that do internal deadtime generation, which is the usual way to do this.

Regards, Dan.