TPS65311-Q1: power up sequence

user3746678

Part Number: TPS65311-Q1

Hi，

1. what is time interval between the rising edge of event and BUCK1 begin to start？just as the following picture described:

2. what is the typical value of tSTART2, in datasheet it just said that the minimum was 0.5ms and maxim was 2ms.

3. what is the typical value of tSTART, in datasheet it just said that the maxim was 3ms.

4. what is the typical value of tSEQ2， in datasheet it just said that the maxim was 3ms.

5.what is the typical value of tSEQ1, in datasheet it just said that the minimum was 1ms and maxim was 4ms.

Thanks

Best Regards.

Gavin.

over 5 years ago

0 Mahmoud Harmouch over 5 years ago

TI__Mastermind 27160 points

Hello, I'm posting the answer and will forwarded it to the person who is supporting this part. Here are the typical values for these parameters from char data:

1- tSTART startup DVDD regulator 0.15ms

2- tSTART2 soft start time for LDO and BUCK1/2/3 1.7ms

3- tSEQ1 3.6ms

4- tSEQ2 0ms

5- Propagation delay from VINPORT to VREG_OK should be very small in the order of few us

0 user3746678 over 4 years ago in reply to Mahmoud Harmouch

Intellectual 400 points

Hi，Mahmound

Thanks for your answer. Please help to answer the following question:

How long the BUCK1 will start after the VIN is OK ?

Thanks.

Best Regards.

Gavin.

0 Krishnamurthy Hegde over 4 years ago in reply to user3746678

TI__Expert 8730 points

Hi,

VIN OK (start of VINPROT) to start of BUCK1 is typically less than 500uS. Also typical soft start time (tSTART2) of each regulator is 1ms. There will be some variations due to application conditions like output voltage settings and output capacitors.

Regards,

Murthy

0 user3746678 over 4 years ago in reply to Krishnamurthy Hegde

Intellectual 400 points

Hi, Murthy

Please help to confirm the following question again, which is very important to us.

Mahmaund has ever helped to answer that tSEQ2=0ms, and I want to konw:

1)whether tSEQ2 is 0ms ?

2)whether that means BUCK1 and BUCK2 are enabled nearly at the same time ?

Thanks

Best Regards.

Gavin.

0 Krishnamurthy Hegde over 4 years ago in reply to user3746678

TI__Expert 8730 points

Hi,

Can you please provide more information about your project, customer details and why power up sequencing time is critical for you?

tSEQ2 is 0ms is a typo error. tSEQ2 is around 1.8ms-typ.

Regards,

Murthy

0 user3746678 over 4 years ago in reply to Krishnamurthy Hegde

Intellectual 400 points

Hi，Murthy

In my design, TPS65311 buck1 supplies 3.3V power for Ethernet Switch VDDO, buck2 supplies 1.8V power for Ethernet Switch VDDP, the following picture describes Ethernet Switch power-up sequence:

Ethernet switch requires thatVDDO-VDDP<2.2V when ramp up.

Thanks

Gavin

0 Krishnamurthy Hegde over 4 years ago in reply to user3746678

TI__Expert 8730 points

Hello,

I am closing this thread as i provided answers to your questions on this topic.

Regards,

Murthy

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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TPS65311-Q1: power up sequence