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TPS7A49: About rising & falling times of TPS7A4901&TPS71501.

Part Number: TPS7A49
Other Parts Discussed in Thread: TPS715

Hi, 

My customer has a question.

 

Q1.

I am checking whether the rise and fall times of the IC are correct.

Are the following rise and fall times appropriate?

 

TPS7A4901

[Using condition]

Vin: 27.7V

Vout: 21.6V

Iout: 0A

Csoftstart: OPEN

Cout: 28.9uF

Startup time: 600us

Shutdown time: 96ms

 

 

TPS71501DCKR

 

[Using condition]

Vin: 4.98V

Vout: 4.11V

Iout: 0A

Cout: 1.2uF

Startup: 130us

Shutdown: 165ms

 

Q2.

In order to check if it is reasonable time,

Do you have materials like evaluation data?

 

(TPS71501 was described in the datasheet (page12)

TPS7A4901DGNR didn't have described.)

 

Q3.

The TPS7A4901DGNR is controlled by the EN pin.

 

From the timing when EN is turned OFF,

How long will it take for the OUT to start falling?

 

 Best Regards,

Watanabe

  • Hi Watanabe,
    For Q1:
    Rise time for TPS7A4901 with Cnr/ss open is approx. 30ms figure 19 of datasheet, you will getting a comparable rise time even if you have Vin =27.7V, Vout = 21.6V , as for shutdown time I am not sure how you got 96ms ! shutdown time is decided by Cout and load connected to LDO output.

    As for TPS715, rise time is approx. 1.2ms figure 14 of datasheet, you will getting a comparable rise time even if you have Vin =4.98V, Vout = 4.11V. Again shutdown time is decided by Cout and load connected to LDO output.

    Q2:
    I didn't understand the question, could you please elaborate more?

    Q3:
    Unfortunately we don't have Vout falling time vs EN pin turning off but we can bench test it base on your system input/out requirements!

    BR,
    Haidar