C6457 McBSP Pin Voltage Translator

Ruifeng Wang

Other Parts Discussed in Thread: TXB0108, SN74AVC4T245

Conditions:

TI DSP C6457 McBSP0 (1.8V) interface with FPGA IO (3.3V) and McBSP1 (1.8V) with MCU IO (3.3V).
TXB0108ZXYR used as voltage translator in between McBSP0/FPGA IO and McBSP1/MCU IO

Q1: Whether TXB0108ZXYR is good fit for this purpose?

Q2: How the TXB0108ZXYR auto-direction sensing done in this IC? Is this auto-direction sensing any impact on our applications for McBSP0/FPGA IO and McBSP1/MCU IO?

over 16 years ago

0 BrandonAzbell over 16 years ago

TI__Guru 64770 points

Ruifeng Wang said:

Q1: Whether TXB0108ZXYR is good fit for this purpose?

Certainly, if the data rate through this level translator is <= 60Mbps. The datasheet for the TXB0108 indicates the maximum data rate. For Vcca=1.8V and Vccb=3.3V, the maximum data rate is 60Mbps.

If you truly need bidirectional signaling on a pin, the TXB0108 is a good fit. If you don't need bidirection, but uni-direction (which typically the McBSP signals are uni-directional), there may be other choices.

Ruifeng Wang said:

Q2: How the TXB0108ZXYR auto-direction sensing done in this IC? Is this auto-direction sensing any impact on our applications for McBSP0/FPGA IO and McBSP1/MCU IO?

The datasheet for the TXB0108 discuss the architecture of the device. Refer to page 10 under the Architecture heading.

0 Ruifeng Wang over 16 years ago in reply to BrandonAzbell

Intellectual 290 points

Could you please recommend a good fit of level translator to uni-directional with high data rate 100Mbps in this case?

Thanks.

0 Ruifeng Wang over 16 years ago in reply to BrandonAzbell

Intellectual 290 points

Q: TXB0108 have Input Driver Requirements which says that: For proper operation, the device driving the data IOs of the TXB0108 must have driven strength of at least +/-2mA. Please confirm C6457 McBSP0/McBSP1/GPIOs driven capacity whether can meet this requirements?

0 BrandonAzbell over 16 years ago in reply to Ruifeng Wang

TI__Guru 64770 points

Ruifeng Wang said:

Could you please recommend a good fit of level translator to uni-directional with high data rate 100Mbps in this case?

Something like a SN74AVC4T245 should work.

0 BrandonAzbell over 16 years ago in reply to Ruifeng Wang

TI__Guru 64770 points

Ruifeng Wang said:

Q: TXB0108 have Input Driver Requirements which says that: For proper operation, the device driving the data IOs of the TXB0108 must have driven strength of at least +/-2mA. Please confirm C6457 McBSP0/McBSP1/GPIOs driven capacity whether can meet this requirements?

If you look at the TMS320C6457 datasheet in the Device Operating Conditions section, Table 6-3 shows the Ioh and Iol for the various pins. All are greater than 2mA.

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C6457 McBSP Pin Voltage Translator