Level translator for RGMII Interface

M-alizzi

Other Parts Discussed in Thread: SN74AUC245, SN74AVC8T245, LSF0204, LSF0101, SN74LV1T34, TXV0108-Q1, TXV0106-Q1

I'm looking for a level translator that can convert an RGMII interface running at 125MHz to/from 1.8 and 2.5V.

One candidate I see is SN74AUC245, do you know if it can be used for RGMII at the above voltages? if not, do you have other recommendations?

Thanks,

over 9 years ago

0 Jennifer Joseph over 9 years ago

TI__Intellectual 2530 points

Hi

Two SN74AVC8T245 (one in each data direction) will be a good solution. Data rates are above your required 250MBps.

Thanks

0 C. Ryan Land over 9 years ago

TI__Genius 9860 points

Hello, the LSF0101 family might be good for this as well. They are flexible high-speed translators available in different numbers of channels. Use the LSF0204 if you are interested in 4 channels.

The SN74LV1T34 buffer can also convert from 1.8 V to 2.5 V.

0 M-alizzi over 9 years ago in reply to Jennifer Joseph

Prodigy 60 points

Hi Jennifer,

I'm looking to run RGMII at 1Gbps, so SN74AVC8T245 won't do. Do you have another suggestion?

I mentioned SN74AUC245 because it supports 250MHz speeds, which is more than RGMII clock (125MHz). What do you think disqualifies it?

0 M-alizzi over 9 years ago in reply to Jennifer Joseph

Prodigy 60 points

Jennifer - I mistook the 250Mbps for total data rate, If I get 250Mbps per data line then it would work.

It's still unclear to me how the chip can do 320Mbps, when it has F @ Nom Voltage (Max) (Mhz) = 100MHz, can you please elaborate on that?

0 M-alizzi over 9 years ago in reply to C. Ryan Land

Prodigy 60 points

Does LSF0101 do 125MHz speeds? The data sheet says it can do above 100MHz and does not list RGMII as a supported interface.

SN74LV1T34 can only do 50MHz.

0 Jennifer Joseph over 9 years ago in reply to M-alizzi

TI__Intellectual 2530 points

Hi

Data rate will depend on power supply and output load. 320Mbps is measured under VCCA>1.8V, VCCB>1.8V and 15pF load.

Where did you get the 100Mhz value from?

Thanks

0 M-alizzi over 9 years ago in reply to Jennifer Joseph

Prodigy 60 points

The 100MHz comes from "F @ Nom Voltage (Max) (Mhz)" parameter here: www.ti.com/.../description

0 Jennifer Joseph over 9 years ago in reply to M-alizzi

TI__Intellectual 2530 points

Hi

Correction noted. We will make the appropriate change to this table.
Please refer to the datasheet for the data rates. Frequency is 2* data rate. For your application, 320MBps is the max data rate.

Thanks

0 Jennifer Joseph over 9 years ago in reply to Jennifer Joseph

TI__Intellectual 2530 points

Typo in previous. Please refer to the datasheet for the data rates. Data rate = 2* frequency. For your application, 320MBps is the max data rate.

0 Bhavya Babu over 7 years ago in reply to Jennifer Joseph

Intellectual 465 points

Hi Jennifer,

320Mbps(Mega bit per second) is mentioned in the datasheet.Is this the data rate per channel of level translator? For example 320Mbps for A1 to B1 pin translation?

Regards,
Bhavya