SN74AXC4T774: Query on Data Translation

Hi Dylan,

Thanks for your reply,

But i have given 2.5V from my PMIC instead of 1.8V, which satisfies VIH High Voltage Input level, will this work or i have to connect to VCCA Compulsory.

By means my DIRx will be connected to VCCB with 2.5V.

Thanks and Regards,

Rajesh G.

Hey Rajesh,

So you aren't translating 1.8 to 3.3 V?

Hi Dylan,

I am translating SPI signals, so 3 signals will be translated from 3.3 to 1.8V and one signal is translated from 1.8V to 3.3V.

2.5 V will work, but might increase the power consumption. You already have 3.3 V at pin 16; just use that for the DIR inputs.

Do you have 0.8 V at all four B pins, or only at the outputs?

Is the voltage at pin 15 correct?

Show everything that is connected to B1/B2/B3. The load might be too high, or some other device might drive a low voltage.

I have already fabricated the Boards, for now I cannot connect DIR Inputs to Pin 16, it is connected to Pin 15 (VCCB) 1.8V/2.5V.

And I have a Variation in all four B Pins from 0.2V to 0.8V.

Voltage at Pin 15 is 1.8V/ 2.5V and which is stable.

Here VCCB will be either connected to 1.8V or 2.5V, because our display will support both 2.5V and 1.8V, 1.8V is the tolerance for 2.5V I/O Voltage.

Attached Complete circuit with Load, and our load is a Display. And I have attached I/O Port Characteristics of my display.

Are you sure that the display pins are actually configures as inputs?

What resistance do you measure between the three RED_xxx signals and ground? If it is not infinitey, does removing U7 or the cable change it?

Hi,

Yes, Display Pins are configured as Inputs, and below are the resistance for RED_xxx and GND Pins:

Pin 14: 2.1MΩ

Pin 13: 1MΩ

Pin 12: 31Ω

Pin 11: 25MΩ

Hi 

Any update?

Hi Rajesg,

I was hoping to see an answer to Clemens question regarding if removing U7 and the cable change the performance?