SN74AVCH32T245: Maximum Pull-up resistor allowed to detect a valid Logic High

Raja Ashutosh Kedia

Part Number: SN74AVCH32T245

Hi,

We are using SN74AVCH32T245 device in our design for 3.3V (I/P) to 1.8V (O/P) transition. We have connected the a pull-up resistor of 10K to 3.3V at the inputs. However, we see that the voltage at input pins of SN74AVCH32T245 device is 1V (possibly due to bus-hold circuitry). Can you please suggest us what is the maximum pull-up resistor that can be used with this device to detect a valid logic high?

Regards

Raja

over 7 years ago

0 Clemens Ladisch over 7 years ago

Guru 269330 points

Section 6.3 of the application report Bus-Hold Circuit (SCLA015) explains how to compute this.

If you are doing only unidirectional down-translation, then you can simply use a buffer with overvoltage-tolerant inputs, e.g., SN74AUC32244 or SN74LVC32244.

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SN74AVCH32T245: Maximum Pull-up resistor allowed to detect a valid Logic High