VME Bus suitable Transceiver at VCC=3,3V

Peio Azkarate

Prodigy 60 points

Other Parts Discussed in Thread: SN74LVTH245A, SN74VMEH22501

Hello,

Powering the chip with 3,3V Vcc, Is the SN74LVTH245A transceiver suitable for VME Bus interface?.

Thanks.

Peio

over 8 years ago

0 ShreyasRao over 8 years ago

TI__Guru 56100 points

Hi Peio ,

Could you please let me know the spec for VME interface ?

0 Peio Azkarate over 8 years ago in reply to ShreyasRao

Prodigy 60 points

Hi,

VME Specifications:

Driver:

VOL=0,6V Max

IOL=48mA(sink)

VOH=2,4V Min

IOH=-3mA(source)

Receiver:

VIL=0,8V Max

VIH=2,0V Min

IIL=-400uA Max

IIH=50uA Max

0 Clemens Ladisch over 8 years ago

Guru 244020 points

VMEbus uses TTL signal levels. The LVT family is compatible with this.

0 ShreyasRao over 8 years ago in reply to Peio Azkarate

TI__Guru 56100 points

Hi Peio ,

yes , the SN74LVTH245A is suitable given your interface requirements .

0 Peio Azkarate over 8 years ago in reply to Clemens Ladisch

Prodigy 60 points

VME bus is a transmision line with 330/470 Ohms on both ends, with overshots/undershots and powered at 5V.
I know the V/I LVT specifications are compatible with VME, but my questions was more about the EMC and SI performance of LVT on VME designs.
People are using LVT in VME designs with good performance?.

0 Clemens Ladisch over 8 years ago in reply to Peio Azkarate

Guru 244020 points

Compared to the original TTL, LVT has higher drive strength (IOL/IOH 64 mA/−32 mA). In theory, this implies that the signals have sharper edges, i.e., SI would get better, and EMC, worse. However, I have no experience with VME, so I don't know if the difference actually matters.

SCEA028 suggests the SN74VMEH22501, which has a drive strength of 12 mA/−12 mA.

Logic

Logic forum

VME Bus suitable Transceiver at VCC=3,3V