HD3SS3220: Verification of expected voltage levels on DIR

Doron Darmoni

Prodigy 125 points

Part Number: HD3SS3220
Other Parts Discussed in Thread: TIDA-00891

Hi,

What is the voltage level of the DIR pin? in the data sheet 6.1 Absolute Maximum Ratings it says both VDD5+0.3 & VCC33+0.3. in the sections 8.2.x application diagrams it is pulled high to VCC33 while on the reference design (TIDA-00891 ) it is pulled high to 5V_COM. in the HD3SS3220A-DFP-EVM it is pulled to 3.3V
What is the DIR polarity? In the data sheet, section 7.2 Functional Block Diagram it shows DIR=0 Tx2/Rx2 as well in the section 7.6.3 Connection Status and Control Register bit 5 description while section 7.3.4 Cable Orientation and Mux Control says : "When a voltage level within the proper threshold is detected on CC1, the DIR pin is pulled low "

Thank you

Doron

over 6 years ago

0 Gerasimos Madalvanos66 over 6 years ago

TI__Intellectual 1350 points

Hello Doron,

1. The low level is specified to be 0.4V, so voltages above that level should be fine. This is why the TI design and EVM both work even though they are pulled up to 5V or 3.3V respectively. The the recommended pull-up resistor is 200k. Ensure the voltage at the pin does not exceed VCC33+0.3V, which the easiest way to do would be to pull up to VCC33.

2. The polarity of DIR is active high.

Best,
Gerasimos

0 Doron Darmoni over 6 years ago in reply to Gerasimos Madalvanos66

Prodigy 125 points

Hello,
1. Sorry, I didn't understand the answer- Is the DIR signal is 3.3V or 5V?
According to your answer- Ensure the voltage at the pin does not exceed VCC33+0.3V what happens if i pull it to 5V? It will exceed the VCC33+0.3V...
2. Sorry, I didn't understand the answer again- what do you mean DIR is active high? low=? High=?
Which indicates CC1/Tx1/Rx1?
Which indicates CC2/Tx2/Rx2?

Thank you,
Doron

0 Gerasimos Madalvanos66 over 6 years ago in reply to Doron Darmoni

TI__Intellectual 1350 points

Hello Doron,

1. DIR signal is VCC33. If you pull it up to 5V the voltage at the pin will not necessarily be 5V. Because this pin is open drain, when the pin is not driven low, it will function as a voltage divider between the pull up resistor and the open drain of the pin. With a sufficiently large voltage drop over the first resistor, the voltage at the pin will still be 3.3V even when pulled up to 5V.

2. CC1/Tx1/Rx1 is when DIR is 3.3V or logic level 1. CC2/Tx2/Rx2 is when DIR is 0V or when DIR is logic level 0.

Hope this helps!

Best,
Gerasimos

0 Doron Darmoni over 6 years ago in reply to Gerasimos Madalvanos66

Prodigy 125 points

Hello Gerasimos ,

it help a lot thank you very much.

should fix the data sheet i think.

Doron

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HD3SS3220: Verification of expected voltage levels on DIR