H-bridge Circuit Please check

[rocky79]

Hello fellows.

I am about to fabricate this H-bridge board and would appreciate any feedback you have regarding this circuit. Any comments is appreciated.
Here is the schematic:

 

[kabeer02]

H bridge as in how? what did you intend to drive,where is the bootstrap circute ?

 

[rocky79]

H bridge as in how? what did you intend to drive,where is the bootstrap circute ?

Each motor has 3 control pins. Enable, Logic1 and logic2. Logic1 and 2 control the motor direction and are controlled by a microcontroller. This circuit is based on an H-bridge IC, why do you need a boostrap circuit?

 

[kabeer02]

wait are you driven direct from the Ic?

 

[rocky79]

wait are you driven direct from the Ic?

Yes, take a look at the sn 754410 datasheet.

 

[sky_123]

You're missing mounting holes (if you want them). It's a classic mistake ; )

 

[explorick]

The ground to the diodes of motors(D2,D4,D6,D8) should be GND-M instead of GND.

 

[rocky79]

You're missing mounting holes (if you want them). It's a classic mistake ; )

I know I have been debating whether to add them or not because that will increase the board size. Now since you mentioned it, I will figure out a way to add them. I think it's a good idea. Thanks for the feedback.

- - - Updated - - -

The ground to the diodes of motors(D2,D4,D6,D8) should be GND-M instead of GND.

Yes, your right. However (motor ground) and ground are connected at connector P1. Thank you for the feedback.

 

[explorick]

The ground should be a star ground as stated in the schematic. So it should not be connected else where. Also it is better to have a ferrite bead which can be mounted based on the need.Else a zero ohm resistor can be populated there.The ferrite bead suppress the noise coupled to GND as motor ground generally is too noisy.

 

[rocky79]

The ground should be a star ground as stated in the schematic. So it should not be connected else where. Also it is better to have a ferrite bead which can be mounted based on the need.Else a zero ohm resistor can be populated there.The ferrite bead suppress the noise coupled to GND as motor ground generally is too noisy.

Good advise, what ferrite bead would you recommend? The IC chip can run a motor up to 2 amps max.

 

[explorick]

You could look into vendor sites like

https://www.murata.com/products/emc/selection_guide/emc/index.html

ensure the footprint is compatible with a zero ohm resistor rated with 2A current.

 

[rocky79]

You could look into vendor sites like

https://www.murata.com/products/emc/selection_guide/emc/index.html

ensure the footprint is compatible with a zero ohm resistor rated with 2A current.

Ok, great thanks. I am unsure about the motor ground on the IC, all 4 ground pins are labeled as ground. I am assuming Motor ground is the on the same side as Vcc2 pin ( pin 4 and 5). The datasheet doesn't mention which ground is which. What do you think?
https://www.ti.com/lit/ds/symlink/sn754410.pdf

 

[explorick]

I would recommend to contact the chip vendor as the internal plane details for the IC will be difficult to predict.

 

[rocky79]

I would recommend to contact the chip vendor as the internal plane details for the IC will be difficult to predict.

I heard back from TI tech support:

" The four ground pins are all part of the lead-frame's die paddle. This is make these pins also the heat sink connection; make sure the circuit board supports heat flow into the board via these four pins. The logic and four power grounds are connected to the same lead-frame"

So I am going to treat all 4 ground pins the same way and have them connected to the same ground plane.