F28335ZHH IBIS file - TDO Model (OC3325CF)

Magnus Wohlfart

Hi all,

a customer reports the following:

"The IBIS file for TMS320F38335ZHH has model for TDO pin named OC3325CF. Signal integrity simulations in Altium Designer show that this pin never goes high. Is this the proper IBIS model? Is OC for Open Collector, while the pin is marked Output in datasheet?"

Open Collector wouldn't make much sense, would it? The way I see it it'll remain low unless there are JTAG commands that tell the processor to output data through this pin to the host, right?

Thanks & kind regards,

Magnus

over 16 years ago

David Foley over 16 years ago

TI__Expert 8500 points

Magnus,

The TDO pin is a JTAG pin. It should not ever toggle in a user application (when TRST is low). It should only toggle in emulation. Your understanding of the pin is correct.

OC does not stand for Open Collector. This is a full rail-to-rail output buffer.

Regards,
Dave Foley

Magnus Wohlfart over 16 years ago in reply to David Foley

TI__Expert 3020 points

As always thanks for your help, it's highly appreciated.

Kind Regards, Magnus

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F28335ZHH IBIS file - TDO Model (OC3325CF)