TUSB1044: Difference between tying directly vs via 1KΩ a 4-Level configuration pin to Gnd or Vcc and if the 1KΩ is actually the maximum allowed to tie but anything in between 0 and 1kΩ is acceptable.

Georg Mussenden

Part Number: TUSB1044

On Table 1 (4-Level Control Pin Settings) on page 20 of the TUSB1044 spec. (www.ti.com/.../tusb1044.pdf what exactly is the purpose of Option1 (tie via 1KΩ) vs. Option 2 (directly tie) ? What happens if it's something in between (e.g. 470Ω)? Is really what this is trying to say that it's Ok to tie with anything between 0Ω and 1KΩ? Is it thus preferable to directly tie or at least tie with something lower than 1KΩ?

over 4 years ago

0 Malik Barton57 over 4 years ago

TI__Guru 64326 points

HI,

It is okay to tie with a resistor between 0 and 1k ohm. 4-level pin Level 0 has a threshold voltage of 0.55V. 1k can be used to further reduce the current consumed by the circuit.

0 Georg Mussenden over 4 years ago in reply to Malik Barton57

Intellectual 280 points

Thanks Malik, some final clarification question on this matter....

You stated that "1k can be used to further reduce the current consumed by the circuit" which I presume means the internal Pull-Up or Pull-Down that I believe is briefly applied to detect what's attached to the configuration pin the 1K perhaps slightly increases the overall resistance of such Pull-Up/Down during the detection instance and that's it.

However, would tying a configuration pin directly to VCC or Gnd as appropriate lead to a more unequivocal detection of the detection of the High(1) or Low(0) level?

Thanks so much,

Georg

+1 Malik Barton57 over 4 years ago in reply to Georg Mussenden

TI__Guru 64326 points

Hi Georg,

TUSB1044 is only monitoring the different 4-level thresholds to determine the pin state. Tying the pin to ND or VCC directly will achieve this.

+1 Georg Mussenden over 4 years ago in reply to Malik Barton57

Intellectual 280 points

Thanks so much again Malik for the so swift reply!

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TUSB1044: Difference between tying directly vs via 1KΩ a 4-Level configuration pin to Gnd or Vcc and if the 1KΩ is actually the maximum allowed to tie but anything in between 0 and 1kΩ is acceptable.