TL7733B: TL7733B deviation in designed time delay and measured time delay

Rahul Kadlag

Part Number: TL7733B

Tool/software:

Hello,

We have issue while using TL7733B, we desinged it for td= 2.6ms. see the schemaric above.

However, when we measured the delay(td) on DSO we geting around 1.8ms.

Positive threshold voltage (VIT+) we have considered as 3V to start the measurement of delay. see the below image.

Can you please tell us why there is difference in the calculated value(2.6ms) and capture value (1.8ms)?

Are we doing measurment in right way ?

0 Jesse Villanueva over 1 year ago

Hi Rahul,

Could you please share the schematic. Also what is the type and tolerance of the capacitor that you are using?

Jesse

0 Rahul Kadlag over 1 year ago in reply to Jesse Villanueva

Hello Jesse,

see the below schematic :

C6 is ceramic cap with ±10% tolerance.

0 Jesse Villanueva over 1 year ago in reply to Rahul Kadlag

Hi Rahul,

Have you tested changing R120 with a 0ohm resistor?

Jesse

0 Rahul Kadlag over 1 year ago in reply to Jesse Villanueva

Hi Jesse,

Yes we tried with 0 ohm, no changes in delay time.

0 Jesse Villanueva over 1 year ago in reply to Rahul Kadlag

Hi Rahul,

What is the ambient temperature of the device?

Also how close is the C6 capacitor in relation to the CT pin?

Jesse

0 Rahul Kadlag over 1 year ago in reply to Jesse Villanueva

Hi Jesse,

Ambient temperature around 25 to 28 degree, and for C6 we placed it closed to CT as per layout guidlines.

0 Jesse Villanueva over 1 year ago in reply to Rahul Kadlag

Hi Rahul,

I will run some bench test based on your configuration. I will give you an update Monday.

Jesse

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