Automotive Grounding Guidance

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KitCarlson
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Posted by KitCarlson: Sun. Dec 26, 2010 - 06:08 PM
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I have developed working stationary electronics for a piezo injector flow bench system. It uses AVR uCs, to PWM control the output signals shape. The system works well, supplied with a switch mode power supply and short load cable lengths. My next step is to make the system mobile for installation in a vehicle. For this application, the 12V power and load cables may extend a few to several feet. Due to the high voltage, and high peak currents, my spider senses are tingling :).

I have concerns in doing this correctly, I welcome guidance from this group. The attached block diagram outlines the general circuit.

My main concern is the logic ground tie between the AVR circuit and the output power circuit, and also case ground.

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Image icon PowerGround.jpg

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Learning and Information, General Electronics
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Kas
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Posted by Kas: Sun. Dec 26, 2010 - 07:43 PM
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Hello,

would split grounds further at ECU/Controller and DC/DC converter and driver. Converter needs only one ground wire imho. Thus there will be a real star layout. Shall 5R stand for 5 Ohm resistor, I would do strongly advice splitting digital grounds.
Would look further to proper decoupling, but that's trivial; don't see more critical areas.

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brunomusw
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Posted by brunomusw: Mon. Dec 27, 2010 - 11:22 AM
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Quote:
My main concern is the logic ground tie between the AVR circuit and the output power circuit, and also case ground

But they are connected toghther only on baterry ground so no problem. BUT on the mosfet driver and load you have 2 ground signals, you will create a current loop over there... Connect just ground of your dc-dc converter to the driver and the load, if it is the source of power for the driver and the load..

Regards,

Bruno Muswieck

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