Auto pulse creator

Yoav Benita

Other Parts Discussed in Thread: TLV840, SN74LVC1G123, TLV809E, TPS3700, TPS3899, TPS3703

Hi,

Im looking for device that create pulse Xms after power up without any external involvement. The picture below show's the operational i want.

over 2 years ago

0 Trailokya Rai over 2 years ago

TI__Genius 11401 points

Do you want a sigle pulse or should it be pulse train ? I can see red and green waveforms ? can you please explain them.

Regards

Trailokya

0 Clemens Ladisch over 2 years ago

Guru 316690 points

Use a reset IC (e.g., TLV809E, TLV840) to trigger a monostable (e.g., SN74LVC1G123).

0 Yoav Benita over 2 years ago in reply to Trailokya Rai

Intellectual 285 points

i need single pulse. the output can be as the green line or as the red line

0 Trailokya Rai over 2 years ago in reply to Yoav Benita

TI__Genius 11401 points

You can use below circuit -

TPS3700 + TPS3899

TPS3700 has one UV and one OV input.
Connect the supply to VDD and OV input INB.
Out B will get asserted after the startup time.
Connect out B to the sense of TPS3899.
CTR pin will genrate a pulse when sense goes down -

Feed it to INA (UV) , CTS will cross the threshold once and it will come down hence you will get a signgle pulse on OUT A.
You can adjust the timing with capacitor on the CTS pin.

Let me know if you have any question.

Regards

Trailokya

0 Yoav Benita over 2 years ago in reply to Clemens Ladisch

Intellectual 285 points

can i make the trigger with resistor and capacitor ? im trying to minimize components.

maybe to use SN74LVC1G123, hold CLRn high, An low and make a RC delay for B to make the rise edge ?

0 Yoav Benita over 2 years ago in reply to Trailokya Rai

Intellectual 285 points

hi Trailokya

I try to minimize components. If you know components that have an overvoltage detector (threshold 0.4-1.2V) and latched after this threshold is exceeded, that could help me.

0 Clemens Ladisch over 2 years ago in reply to Yoav Benita

Guru 316690 points

You can use the '123 alone, if you can live with the RC delay not being very accurate.

0 Yoav Benita over 2 years ago in reply to Clemens Ladisch

Intellectual 285 points

thanks Clemens

If you know components that have an overvoltage detector (threshold 0.4-1.2V) and latched after this threshold is exceeded, that could help me also.

0 Trailokya Rai over 2 years ago in reply to Yoav Benita

TI__Genius 11401 points

Hi Yoav

I will let you know .

Regards

Trailokya

0 Trailokya Rai over 2 years ago in reply to Trailokya Rai

TI__Genius 11401 points

Hi Yoav

TPS3703 has latch feature where you can take the CT voltage below VCT and latch the reset.

You need to take the CT voltage above VCT with some RC. Also you need to slow downm your single pulse if you want to use only one IC. Please refer below app not https://www.ti.com/lit/an/snva836a/snva836a.pdf?ts=1672039096371&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS3820 for more details.

Regards

Trailokya

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