LM25066I: ADDR0 Pin connect to GND over a Schottky diode

Michael Liesenberg85

Mastermind 7560 points

Part Number: LM25066I
Other Parts Discussed in Thread: TLA2528, , LM25066

Hi,

i am having a I2C address conflict if i connect LM25066i and the TLA2528 ADDR pin configuration together.

In one slot both ADDRR are connect to GND and on the other slot the are left open.

I found a solution by adding a schottky diode blocking the ADDR0 from LM25066i from TLA2528.

i would like to know the tolerance from ADDR0 by "seeing" GND for the address configuration, because once i add the schottky i have a 0.2V drop over it and GND.

What i mean is that i need to add a diode in serial with ADDR0 to GND so the TLA2528 set the correct address, otherwise TLA2528 address configuration is wrong.

Would the BAT54W not interfere in the LM25066i Address selection? What is the tolerance/threshold from ADDR0?

ADDR0 is left floating in one configuration and connected to GND in an other configuration.

Best regards,

Michael

over 3 years ago

0 Avishek Pal over 3 years ago

TI__Mastermind 30915 points

Hi Michael,

Thanks for reaching out to us. I will get back to you tomorrow.

0 Avishek Pal over 3 years ago in reply to Avishek Pal

TI__Mastermind 30915 points

Hi Michael,

The effect of BAT54W on the ADR0 selection needs to be verified on the hardware. I didn't get the tolerance or threshold for sampling ADR0 as "0" or "1".

0 Michael Liesenberg85 over 3 years ago in reply to Avishek Pal

Mastermind 7560 points

Hi Avishek,

on the hardware it works but i want to be sure that it wont affect the ADR0 to be 0

Can TI confirm this?

Or what is the threshold to be 1, is it the pullup to DECAP?

What is the internal circuit from ADR0?

0 Avishek Pal over 3 years ago in reply to Michael Liesenberg85

TI__Mastermind 30915 points

Hi Michael,

If ADR0 is pulled up to VDD (4.5 V nominal) of LM25066, it's detected as "1". Voltage output on DECAP pin of TLA2528 is 1.8 V. I am not sure if ADR0 of LM25066 is pulled up to 1.8 V, whether it's detected as "1" or "0". But this one I can verify on the EVM tomorrow by pulling ADR0 up to 1.8 V through an external power supply. Or you can also check on your system.

0 Michael Liesenberg85 over 3 years ago in reply to Avishek Pal

Mastermind 7560 points

Hi Avishek,

that would be great if you can test it.

Because i dont know the internal circuit of LM25066i, i cannot tell if ADR0 sees the 0.2V drop from the schottky or not.

Is there any current/voltage use inside the ADR0 PIN rom LM25066i that recognizes PULL UP/PULL Down or Floating?

i use the circuit above in at least 4 boards and it works but i cannot tell if it always work because the schottky has a voltage drop o 0.2v and i dont know if this would affect the logic.

Best regards,

Michael

0 Avishek Pal over 3 years ago in reply to Michael Liesenberg85

TI__Mastermind 30915 points

Hi Michael,

Please let me perform the experiment. I will get back to you tomorrow or day after tomorrow.

+1 Avishek Pal over 3 years ago in reply to Avishek Pal

TI__Mastermind 30915 points

Hi Michael,

Please see the range below.

0 V to 0.79 V : ADR0 = 0;

0.8 V to 3.4 V : ADR0 = Z;

3.41 V and above : ADR0 = 1.

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LM25066I: ADDR0 Pin connect to GND over a Schottky diode