TXB0108: TXB0108NMER

thank for reply,

CLR from TXB010B pull low to GND, and CLR dont have signal on it.

But output CLEAR go high when VCCA from 0 to 3.3V, so i set CLR by 47kohm on it, but it seem dont work,

and I try to change 47kohm to 1kohm , and i add capacitor 0.1uF on OE pin to seperate VCCA and OE timing sequence,

it can work properly, i will try it again by other PCB

thanks

thanks for reply,

because when i do the test at output,

i connect output pin of level shifter with 5V,  and i float at output pin, 

output pin may keep 5V after testing,  and the input  turn into high and output pin keep high, 

i think there is some spike at output, this situation let output pin have some false status

but if i suddenly touched to 0V with wire at output, input and output comes to 0V,

so  i change pull low resistor to 1kohm, the CLR/CLEAR keep low all the time, 

CLR is not use when the circuit  is working, so i change input pull low resistor to 1kohm, 

is it suitable?

With 1 kΩ, the TXB will not be able to drive the pin high. I do not know if this would be required in your circuit.

Hey Stone,

The TXB's internal architecture is always actively driving the outputs, while also having the signal being driven back into the input side as well:

Following through with Clemens' response, please see the Effects of pullup and pulldown resistors on TXS and TXB devices for more information.

Regards,

Jack 

thanks CLEMENS, JACK

we use CLR pin as system control digital siganl as original,

but we break the route with remove resistor between CLR and system finally, 

so TXB dont drive pin high anymore, 

in order to use this PCB version, we just use pull low resistor as 1kohm,

it is not smart method, but we can use this PCB version now, 

this is why we only use this method to correct this fault status for this PCB version, 

we will modify it next time if new version

Hey Stone,

I see- please let us know if you come across any other issues. I will now close this thread.

Regards,

Jack