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TXB v/s TXS selection

Anool Mahidharia
Prodigy 80 points
Other Parts Discussed in Thread: TXB0104, TXS0206-29, TXS0206A

Hi,

We're designing an interface card (shield) for the Raspberry-Pi (Broadcom BCM2835 ARM processor). Our shield is based on the Atmel ATMega processor (ATMega328P). We will have two communication interfaces between the ARM processor at 3.3 V and the ATMega processor at 5V.

1. Two wire I2C using SDA and SCL

2. Serial communication using UART (Rx, Tx and GND).

3. Finally, we need two spare interface signals from the ARM GPIO to the ATMega. These may be used to reset the ATMega, for example.

That's a total of 6 signals between the ARM GPIO pins and the ATMega.

Can you clarify which specific voltage translation device would be suitable ? The application notes recommend a TXS type device for I2C applications. Can the same type of device be used for serial UART application ?

 We will also have a uSD card interfaced to the ATMega. For uSD interface, please confirm if the TXB0104 is suitable.

Anool J M : anool@wyolum.com

  • 0
    TI__Expert 4705 points

    Hi, Anool,

    Thanks for your thinking about TI part. For your application, it is better to use our TXS family part.

    The TXS parts can be used both at Open drain (I2C) and push pull mode(UART), since you have 6 channels, we prefer to use the TXS0108 since no 6 channels part.

    The key things need to be check for TXS0108 are below:

    1. UART data rate, at push pull mode, the TXS0108 can work up to 60MBPS from 3.3V to 5V  translation. I think if standard UART, it  should be OK.

    2. Checking the Vil, Vih requirement for TXS0108 and Vol, Voh for TXS0108, whether it can be connectted to the driver and receiver. please note TXS0108 doesn't have high current drive capability. For Voh only 20uA, for Vol 400uA.

    For your uSD card interface, were you talking the microSD card? if so , we have the TXS0206A, TXS0206-29 and SN74AVCA406E, they are special for SD interface. please check and see. any further questions, please let me know.

     

    BR
    Junjie