ISO7842 - DC-refresh pulse

Hirotaka Matsumoto

Other Parts Discussed in Thread: ISO7842, ISO722M, ISO722

Hi all,

Would you mind if we ask ISO7842?

ISO73XX has DC-refresh pulse in order to correspond DC input.
(The datasheet shows a periodic update pulse is sent across the barrier to ensure the proper dc level of the output.)
ISO7842 has the same function(DC-refresh pulse), doesn't it?

And then, we don't understand the theory of DC-refresh.
So, if it is possible, could you let us know DC-refresh pulse?

Kind regards,

Hirotaka Matsumoto

over 8 years ago

0 Oleksiy Pazyuk over 8 years ago

Expert 2585 points

Hi, Hirotaka,

Could you explain what do you mean for "DC-refresh pulse". As I know there is no need for additional pulses for normal operation of the TI digital isolators.

0 Hirotaka Matsumoto over 8 years ago in reply to Oleksiy Pazyuk

Guru 27525 points

Hi Oleksiy san,

Thank you for your prompt reply!
The datasheet P1 of ISO722M shows "If this dc-refresh pulse is not received ～".
So, we guess that it is inside content.

Kind regards,

HIrotaka Matsumoto

0 Oleksiy Pazyuk over 8 years ago in reply to Hirotaka Matsumoto

Expert 2585 points

Hi HIrotaka san,

As I see, according to the datasheet ISO7842 has differ method of transferring DC signal through barrier than ISO722 or ISO73xx. In ISO78xx is using kind of RF modulation. Thus I guess no internal dc- refresh pulse is required.

0 SaranganValavan over 8 years ago in reply to Oleksiy Pazyuk

TI__Intellectual 1815 points

Matsumoto -san,
Oleksiy is correct. The Iso78xx series uses ON OFF keying modulation to transmit the signal which inherently has the DC information also. So there is no need for DC refresh in the ISO78xx devices.
Regards,
Sarangan Valavan

0 Hirotaka Matsumoto over 8 years ago in reply to Oleksiy Pazyuk

Guru 27525 points

Olelsiy san,

Thank you for your reply!

Kind regards,

Hirotaka Matsumoto

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ISO7842 - DC-refresh pulse