I2C - level translator and multiple slaves.

Thread Starter

robotDR

Joined Mar 17, 2020
54
Hi Thank you for taking a look.

I am using level translator TCA9803.

I have a 1.8v master and (4x) 3.3v slaves.

The datasheet seems to imply that I have to run a TCA9803 translator for each slave. Is that true? So I have a 1.8v bus with 4 translators each with a slave on 4 isolated 3.3v bus?

Or can I do (1x) translator with 4 slaves on the (1) 3.3v bus. It seems to say the leakage current could be too much for the TCA9803 if I have multiple slaves on one translator?

Thank you for your time.
 

Deleted member 115935

Joined Dec 31, 1969
0
it says the leekage current must be below 100 uA
what is the leekage current of your devices ?
 

Thread Starter

robotDR

Joined Mar 17, 2020
54
it says the leekage current must be below 100 uA
what is the leekage current of your devices ?
Hi Thanks for taking your time to look over this.

I am using (4)
TCA9555DBR
GPIO expanders as the 4 slaves.

It says the SDA and SCL input leakage current is +/- 1uA so that should be fine right?

So does that mean I can use 1 translator, and 4 slaves on the translated bus (3.3v)


MASTER (1.8v) --> Translator --> Slave 1 (3.3v)
|---> Slave 2 (3.3v)
|---> Slave 3 (3.3v)
|---> Slave 4 (3.3v)
 

Deleted member 115935

Joined Dec 31, 1969
0
Hi Thanks for taking your time to look over this.

I am using (4)
TCA9555DBR
GPIO expanders as the 4 slaves.

It says the SDA and SCL input leakage current is +/- 1uA so that should be fine right?

So does that mean I can use 1 translator, and 4 slaves on the translated bus (3.3v)


MASTER (1.8v) --> Translator --> Slave 1 (3.3v)
|---> Slave 2 (3.3v)
|---> Slave 3 (3.3v)
|---> Slave 4 (3.3v)

to me 4 * 1 uA is much less than the limit,
so 4 slaves afte rthe dirver is fine,

Remember, no pull up needed after the driver,
pull up is built in the driver,
 
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