TPS7A24: How to know Startup time / Soft start

teritama

Expert 1570 points

Part Number: TPS7A24

Hi team,

Our customer want to know information of startup time in this device.

It is necessary that startup time is more than 33us because of power up slew rate requirement in load side.

Do you have some information about startup time in this device?

If there are no information, Could you recommend me other device that is equivalent price?

Best regards,

teritama

over 3 years ago

0 teritama over 3 years ago

Expert 1570 points

Hi team,

I need your information in order to make report.

Could you let us have your answer by this week?

If you're not clear about anything, please tell me.

Best regards,

teritama

0 Juliette over 3 years ago

TI__Genius 16776 points

Hey Teritama,

It seems as if my reply never posted,

But there are many things that influence Start-up time - temperature, load, slew rate, enable etc.

I do have scope shots of this device performing with a start-up ranging from 500us to 1.4ms, so it is definitely possible to have a start-up time greater than 33us.

Best,

Juliette

0 teritama over 3 years ago in reply to Juliette

Expert 1570 points

Hi Juliette,

Thank you for your reply.

I understood that start-up time will be 500us to 1.4ms.

Is there a way to roughly guess start-up time?

Or could you introduce me the device can be used in following condition and be specified start-up time?

Vin:12V

Vout:3.3V

Iout:100mA

Best regards,

teritama

0 Juliette over 3 years ago in reply to teritama

TI__Genius 16776 points

Hi Teritama,

I can do a cadence simulation. What capacitors would you be using [Cin, Cout, Cff]?

Best,

Juliette

0 teritama over 3 years ago in reply to Juliette

Expert 1570 points

Hi Juliette,

I will use TPS7A2433, so not use Cff.

Cin=1uF, Cout=2.2uF

Best regards,

teritama

0 Juliette over 3 years ago in reply to teritama

TI__Genius 16776 points

Hi Teritama,

I will reply with a simulation model as soon as the designer sends it to me.

Best,

Juliette

0 Juliette over 3 years ago in reply to Juliette

TI__Genius 16776 points

Hi Teritama,

Below is the snapshot of the startup behavior with the conditions that you mentioned :

Cout = 2.2uF, Vin = 12V, Vout = 3.3V, Iload = 100mA

The one in green is with VIN & EN tied together and the one in red is with EN coming up separately at 300us.

For both the cases, startup time is around 51us (measured from 10% to 90% of Vout).

Best,

Juliette

Power management

Power management forum

TPS7A24: How to know Startup time / Soft start