TUSB4041I: Recommended LDO for VDD (1.1 V)

Masanori Tachibana

Part Number: TUSB4041I
Other Parts Discussed in Thread: TPS74801

Hello support team,

I have a question about TUSB4041I.

Regarding the current consumption of VDD (1.1 V power supply), the typical value is described in "7.7 Hub Input Supply Current" of the data sheet. And for example, it is 86 mA for ACTIVE MODES 2.0 host / 4 HS device.
So the customer tried to use 100 mA type of LDO.

However, it seems that 300 mA or more of current flows on VDD (1.1 V power supply) while GRSTz is 'L' at power supply startup. Therefore, this device cannot start well.

Could you advise me how much mA type of LDO is recommended for VDD (1.1 V)?

Sincerely,
M. Tachibana

over 7 years ago

0 Michael.Walker over 7 years ago

TI__Mastermind 19720 points

when you say "at power supply start up" what do you mean? What is the power up sequence of the 3.3V and 1.1V power? how long do you see the 300 mA current? how long are you holding GRSTz low?

0 Masanori Tachibana over 7 years ago in reply to Michael.Walker

Genius 5350 points

Hello Michael-san,

The power-up sequence is as follows.
1. VDD (1.1 V) is supplied from LDO (100 mA type).
2. After approximately 3 ms, VDD33 (3.3 V) is supplied from DC-DC.
3. Keep GRSTz 'L' for about 3 ms or more.
4. Set GRSTz from 'L' to 'H'.

Approximately 300 mA of supply current flows to VDD (1.1 V) during the above "1" to "3 " periods.
Since the LDO is 100 mA type, the voltage of VDD does not rise to 1.1 V, it is about 0.8 V. So, TUSB 4041I is not powered up well.
The customer would like to change the LDO to a large current type, so please tell me the recommended LDO.

Sincerely,
M. Tachibana

0 Michael.Walker over 7 years ago in reply to Masanori Tachibana

TI__Mastermind 19720 points

I would recommend an LDO with 500 mA max output as a minimum. For a specific LDO I would recommend the TPS74801 because we use this LDO on the TUSB4041 EVM.

0 Masanori Tachibana over 7 years ago in reply to Michael.Walker

Genius 5350 points

Hello Walker-san,

Thank you for teaching me.
TPS74801 is LDO for 1.5 A.
Is it OK to use another LDOs for 500 mA?

Sincerely,
M. Tachibana

0 Michael.Walker over 7 years ago in reply to Masanori Tachibana

TI__Mastermind 19720 points

Yes, it should be ok as long as the LDO can supply up to about 500 mA.

0 Masanori Tachibana over 7 years ago in reply to Michael.Walker

Genius 5350 points

Hello Walker-san,

Thank you for taking your time.
I understood and will inform the customer.

Sincerely,
M. Tachibana

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TUSB4041I: Recommended LDO for VDD (1.1 V)