TXS0108E: schematic check

Hey Jeff,

It seems that the device is being used for a variety of push-pull and open drain signals, which the TXS0108E will be able to support. The configurations in the schematic seem fine to me- bypass caps. sized accordingly, no external pullups/ pulldowns on the I/O lines since the device has internal 10kohms and VCCA <= VCCB. However, on U25, please note that when the VCCB is biased to 3V3 or 5V, the I/Os connected on B-side will see the same voltage due to the internal pullup. 

There aren't any immediate drawbacks that I can think of with using the 33ohm series resistors- more so the application that I am concerned with. With the series dampening resistors in the schematic, I am assuming that the signals are being driven over long distances in effort to impedance match with a potential transmission line. Could you please confirm the length of connectors/ PCB traces is below the <70pF loading condition as mentioned in section 10.4.1 of the datasheet? 

If signal integrity is being compromised, you may also see this app note for more suitable translators depending on the interface of the signals.

Regards,

Jack 

Hey Jeff,

Allow me to clarify- the TXS0108E is designed to drive light capacitive loads <70pF due to the design of the internal one shots as seen section 10.4.1. You may refer to this app note for further clarification on the 70pF: Do’s and Don’ts for TXB and TXS Voltage Level-Shifters with Edge Rate Accelerators

Transmission Line Effects FAQ

Regards,

Jack