TUSB321: UFP mode query

Shashank Meti

Part Number: TUSB321

My Customer is using TUSB321 in their current project.

Regarding the mode selection, when we are selecting UFP mode using the PORT pin, I need clarification regarding current detection/advertisement (Table 2).

If we connect the OUT1/2 in UFP mode for current detection (say both LOW), then will the device limit its current to 3A?

Will the host limits the current to the device to 3A or will it supply more current in need?

over 3 years ago

0 Malik Barton57 over 3 years ago

TI__Guru 64326 points

Hi Shashank,

Once the UFP has detected the advertized current it should modify its current consumption to match. DFP max power output can vary device to device and it should not be assumed that the DFP can supply more than 3A. According to the Type-C spec, "The host needs to assume that the device will continuously draw up to the offered limit."

0 Shashank Meti over 3 years ago in reply to Malik Barton57

TI__Intellectual 950 points

Hi Malik,

Does this mean in UFP mode device can draw more than 3A as well?

0 Malik Barton57 over 3 years ago in reply to Shashank Meti

TI__Guru 64326 points

Hi Shashank,

UFP should not draw more than DFP advertises, if more power capability is need a PD controller is needed.

0 ASHLY GEORGE over 3 years ago in reply to Malik Barton57

Prodigy 10 points

Hi,

The OUT 1/2 pins are described as open drain output. Is it enough pulling both these pins to ground to set the device to 3A mode?

Will the device be able to draw upto 3A only with this configuration (PORT pin in UFP mode and OUT 1/2 pulled LOW)?

0 Malik Barton57 over 3 years ago in reply to ASHLY GEORGE

TI__Guru 64326 points

Hi,

These pins are outputs. A UFP does not set the current capability of the Type-C connection. The DFP will advertise it current capability and the UFP is responsible for detecting that advertisement and consuming current appropriately. OUT 1 & 2 will output the current capability detected over the CC line.

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TUSB321: UFP mode query