DAC8742H: Hardware changes to use HART and Field bus

Remya R

Part Number: DAC8742H
Other Parts Discussed in Thread: PROFIBUS, ,

We want to use both HART and profibus /Fieldbus with DAC8742H. As per my understanding only below hardware changes are required to use both protocols. Please confirm.

	HART	Profibus/Field Bus
1	Requires parallel capacitance of 5-22 nF in MOD OUT pin	Requires parallel capacitance of 0-100 pF in MOD OUT pin
2	If using the internal band-pass filter, connect 680 pF to MOD_INF pin	If using the internal band-pass filter, connect 120 pF to MOD_INF pin
3	External Clock 3.6864MHz/1.2288MHz	External Clock 4MHz

Please let me know if any other hardware circuit required to use both protocols.

over 4 years ago

0 Paul_Frost over 4 years ago

TI__Guru 53623 points

Hi Remya,

It is a bit hard to have a single layout support both, as they need separate filtering frequencies and clocks. You can make a PCB that supports both, but you will need separate hardware paths. You can see how we made the DAC8742HEVM to support both, but we have jumpers to set the input path.

Are you trying to make this dynamic? Or just have board variants?

Thanks,

Paul

0 Remya R over 4 years ago in reply to Paul_Frost

Prodigy 180 points

Hi Paul,

Thank you.

We are plan to keep two Bill of materials with same PCB.

0 Paul_Frost over 4 years ago in reply to Remya R

TI__Guru 53623 points

Hi Remya,

You would then implement the circuit similarly to the EVM, but just have two different boms. The EVM is a good reference for this.

Thanks

Paul

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DAC8742H: Hardware changes to use HART and Field bus