SN74LVC1G123: Period of discharge time at Rext/Cext pin

Daisuke Higa

Part Number: SN74LVC1G123

Hi support team.

How long does Cext discharge?
Is it constant or do any of them vary with conditions?
Currently, when I monitor the voltage of the Rext/Cext pin, it does not drop to 0V.Is this normal?

Best regards,

Higa

over 2 years ago

0 Emrys Maier over 2 years ago

TI__Guru* 97046 points

Hello Higa-san,

Can you share your circuit and component values? Are you operating within the datasheet specifications / provided values?

0 Daisuke Higa over 2 years ago in reply to Emrys Maier

Genius 4340 points

Hi Maier-san

Thank you for your reply.

Currently components are below.

Rext=100k

Cext=10uF

I'm sorry did not get Schematics from my customer.

I can not find the maximum limit value of Rext and Cext in datasheet.

Best regards,

Higa

0 Emrys Maier over 2 years ago in reply to Daisuke Higa

TI__Guru* 97046 points

Hello Higa-san,

The datasheet provides timing for a limited set of options for Rext and Cext:

Customers can exceed these provided values, but we can only provide limited support when going outside the recommended specs. The highest value shown is 1uF (10^6 pF).

In general, we recommend building a prototype with these devices using the planned R and C components to get timing information.

0 Daisuke Higa over 2 years ago in reply to Emrys Maier

Genius 4340 points

Hi Maier-san

Thank you for your reply.

I would like to know whether it is normal or abnormal that the Rext/Cext does not drop to GND during discharge.
Is it correct that if Cext is 1uF, it will drop to GND?

Best regards,

Higa

0 Emrys Maier over 2 years ago in reply to Daisuke Higa

TI__Guru* 97046 points

That is not a specification of the device. Is your device producing the displayed output pulse width when using an R and C within the datasheet specifcations?

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SN74LVC1G123: Period of discharge time at Rext/Cext pin