Other Parts Discussed in Thread: , DRV8220, DRV8870
I apologize if this is not the right page for this question, but I couldn't find a relevant forum for my topic.
I am tasked to redesign my current VFD filament driver that has been obsoleted, and I think either the DRV8876/DRV8876N or the new DRV8220 might serve the purpose. But I need advice on a few things.
Before that, let me brief you the required specification of my VFD. My board don't have access to the center tap of the transformer so I can only drive it with bipolar pulses. I think a H-bridge driver is capable of doing this for me. The filament supply will be generated from the on-board 12V supply to create a alternating pulse drive with 22% duty cycle at 10kHz. The waveform of the pulse will be provided by a 3.3V MCU to this driver. IN+ will be a 10kHz D=22% pulse and IN- is the same pulse but with 50us delay.
This should give me roughly 6Vrms to turn on the filament of the VFD. The peak current is around 450mA and the average output current is abt 300mArms.
From here, I have a few thing that need to be addressed and I hope you can help me with this.
1. My VFD requires Ek = 0.8VDC for proper filament bias. I think I could connect a forward bias diode to the PGND of DRV8876 to create this Ek. Can it be done this way?
2. There is a few functionality that I do not need from DRV8876, and I found your new DRV8220 which I think can be used. However, DRV8220 does not have a PGND that I can use to create Ek. Can I connect the the diode to GND pin of the DRV8220 instead?
3. When can I expect DRV8220 to begin mass produce and widely available?
4. Will there be any issue if I were to use a motor driver to drive my filament? If yes please let me know. I would also appreciate if you could introduce some alternative for me.