Need help with troubleshooting a gate driver circuit

[OM222O]

If I understand that correctly, it measn 50% duty cycle means motor is off, below that (down to 10%) means for example clockwise rotation and above that (up to 90%) means counter clockwise rotation?

Yup 

Now the next question is - how big is the motor you are controlling? Do you have any current monitoring?

The specific ones for these project are fairly small (1200mA / 4.5A stall) but I'm planning on using the board as a general H bridge in the future, so I chose mosfets that can handle 20A. I don't think I'll have an issue with any motors in the near future. I am using INA213s for current monitoring (it's a dual H bridge if you couldn't tell from the PCB) but they're really annoying to solder. I was considering just getting an op amp and some resistor to create my own current monitoring circuit. If you know any chips that are not fine pitch ICs please let me know.

[OM222O]

One option could be to use a 3rd self-oscillating DGD0506A to produce the Vb for the other 2.

DIR/IN and PWM/EN would stay exactly as they are, and the H would work down to DC or 100% PWM because the Vb for the upper mosfet is always available. I guesstimate the average Vb current needed for one full H @ 20kHz PWM to be only about 30mA.

I'm guessing that the second capacitor (Vvb 20v) should be connected to Vs on the negative side not ground? if no, then what should be connected to Vs? GND?

[StillTrying]

"I'm guessing that the second capacitor (Vvb 20v) should be connected to Vs on the negative side not ground?"

No, just GND/COM. The final cap already has the full 20V Vb on it, it doesn't have to do the 12V+10V Vs H-switching thing.

LO is a 0V to 12V square wave, Vb would be a 11V to 22V squarish wave, 20V Vb stays charged at the ~20V Vb voltage.

"what should be connected to Vs"

Nothing, it only uses the 2 internal mosfets on the LO side.

It's just an idea to create a simple voltage doubler for an independent Vb.

[OM222O]

"I'm guessing that the second capacitor (Vvb 20v) should be connected to Vs on the negative side not ground?"

No, just GND/COM. The final cap already has the full 20V Vb on it, it doesn't have to do the 12V+10V Vs H-switching thing.

LO is a 0V to 12V square wave, Vb would be a 11V to 22V squarish wave, 20V Vb stays charged at the ~20V Vb voltage.

"what should be connected to Vs"

Nothing, it only uses the 2 internal mosfets on the LO side.

It's just an idea to create a simple voltage doubler for an independent Vb.

The same result could be achived with a simple charge pump tho, you just need a discrete transistor to turn the 3.3v PWM to 12V PWM, then use a double diode and a capacitor. that's gonna be cheaper and uses less components, plus it's easier to solder by hand. Isn't that true?

[StillTrying]

"The same result could be achived with a simple charge pump tho"

That's what it is, the advantage in using a mosfet driver would be the higher +/- output drive current.

"3.3v PWM to 12V PWM, then use a double diode and a capacitor."

You could use the PWM/EN signal, but you'd have to keep the duty within ~10% - ~ 90%.

I did think of mangling the PWM/EN and DIR/IN signals to keep the Vbs charged, or using 4 signals, a separate IN and EN for each half of the bridge, but I think producing an independent Vb would be better because it keeps the simple DIR/IN and PWM/EN arrangement you already have, and allows the full PWM 0% to 100%, but it's up to you which method you want to try!