CDCDB400: I2C address issue

chih-wei chao

Part Number: CDCDB400

pin : SADR0

according to datasheet , It has internal 120-kΩ pullup / pulldown network biasing to VDD/2 when no connect. For a mid-level input configuration, the pin should be left floating and not
connected to VDD or ground. and its I2C address should be 0XDA

But , when I tried to check the I2C address , I found that I2C address is 0XD8 not 0XDA ( when I float this pin)

I also tried to use an external pullup resistor / an external pulldown resistor / external pulldown ,pullup resistor ==> the result of I2C address is good.

I want to confirm if is there any updated spec for this pin : SADR0 ?

over 3 years ago

0 Ajeet Pal over 3 years ago

TI__Genius 12560 points

Hi,

Ideally for SADR0 pin floating, its voltage would be mid value (VCC/2) and should read the correct I2C addres.

Can you possible to probe the voltage at the SADR0 pin and see how much it is? There could be reason of short to ground with could acts as external pull down this pin.

Can you also share the schematic circuit for SADR0 input pin?

Thanks!

Regards,

Ajeet Pal

0 chih-wei chao over 3 years ago in reply to Ajeet Pal

Prodigy 20 points

1. the voltage at the SADR0 pin is about 0V

2. the impendence between SADR0 and GND is 189K ohm , it seems that it doesn't short to ground

3. is there any function impact if connect pin 10 , 11 , 17 , 30 to GND?

0 Ajeet Pal over 3 years ago in reply to chih-wei chao

TI__Genius 12560 points

Hi,

Thanks for your inputs.

From the design, it seems address pin (SADR0) has 180kohm pull down when left floating. What you are seeing is correct.

We need to update the datasheet for mid voltage setting for correct I2C address.

Hence, for now it would need an external pull up and pull down resistors for mid voltage settings.

Thanks!

Regards,

Ajeet Pal

0 chih-wei chao over 3 years ago in reply to Ajeet Pal

Prodigy 20 points

Thanks for your help.

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CDCDB400: I2C address issue