TL431A: TL431ACDBZR

hamidreza maddah

Part Number: TL431A

Dear

I Used TL431ACDBZR in my design.

In data sheet told, there is some marking code for this part. TAC3, TACS , ...

The marking code of the chip that I designed my board with, was TACS.

after production, I saw failure in this part. I have checked the marking code and it was TAC3.

I compared these to parts ( TAC3 and TACS). It seems the input current of Vref pin are difference.

really, Is there any difference?

if there is difference, why the part number is the same?

Best Regards,

Hamidreza

over 6 years ago

0 Diego Lewis over 6 years ago

TI__Intellectual 1540 points

Hi Hamidreza,

The last letter on the code stand for the assembly and test site, however the parts are the same.

What is the issue that you are seeing with the part?

Regards, Diego Lewis

0 hamidreza maddah over 6 years ago in reply to Diego Lewis

Prodigy 110 points

Dear Diego,
In my circuit, I have divided the voltage with resistors to detect under voltage. But the voltage that these 2 parts are detecting, is not the same
Regards
hamid

0 Diego Lewis over 6 years ago in reply to hamidreza maddah

TI__Intellectual 1540 points

Hi Hamid,

Do you get the same voltage for parts with the same top marking?

What are the voltages that you are getting and what resistor values are you using?

Here is a link to an application note that goes over some of the variations you can expect when setting the shunt voltage.

Regards, Diego Lewis

0 hamidreza maddah over 6 years ago in reply to Diego Lewis

Prodigy 110 points

Hi Diego

I get the part with same voltage. but marking codes are TACS and TAC3

The resistors value: R1 = 240 ohm. R2 = 2K , a series resistor with anode = 3.3K.

How can I send the schematic for you?

Regards

Hamidreza

0 Diego Lewis over 6 years ago in reply to hamidreza maddah

TI__Intellectual 1540 points

Hi Hamidreza,

While the marking is different, the parts are the same.

You can attach the relevant part of you schematic to this post by clicking "use rich formatting" on the bottom right of the text box.

Once there you can click on the add media button to add your image. (the icon below the eraser button)

What are the output voltages you are seeing? What is your supply voltage?

Regards, Diego Lewis

0 hamidreza maddah over 6 years ago in reply to Diego Lewis

Prodigy 110 points

Hi Diego

When The VBAT or Vin is more that Vcut, The Voltage on cathode of TL431 will Turn on the FET. And when the Voltage of VBAT and Vin go under of Vcut, the cathode of TL431 will be open collector and the FET will be turn of.

My problem : the Vcut changes, when I use TACS or TAC3 marking code.

Best regards.

Hamid

0 Diego Lewis over 6 years ago in reply to hamidreza maddah

TI__Intellectual 1540 points

Hi Hamid,

What values are you getting for Vcut with the two markings? The TL431A is a 1% initial accuracy part and I see that you are using 1% resistors.

Not taking into account other variations, your initial accuracy for Vcut is already 1.2%.

Also, what is the purpose of C87? Usually a capacitor would be placed between the cathode (Pin 1) and ground (Pin 3).

Regards, Diego

0 hamidreza maddah over 6 years ago in reply to Diego Lewis

Prodigy 110 points

Hi Giego

The Vcut when I use the part with marking code TACS is 3.1V and with TAC3 is 3.6V.

I use C87 to prevent cutting in current peak.

Best Regards,

Hamidreza

0 Diego Lewis over 6 years ago in reply to hamidreza maddah

TI__Intellectual 1540 points

Hi Hamidreza,

Do you get 3.6V if you try other parts with the TAC3 code?

If possible, can you check the part giving you 3.6V by itself? You can do this by shorting the REF pin to the CATHODE pin, grounding the anode, and applying 5 volts in series with a 1K resistor to the cathode and measuring it's voltage.

Regards, Diego Lewis

0 hamidreza maddah over 6 years ago in reply to Diego Lewis

Prodigy 110 points

Hi Diego,

I get 3.6V with 6 sample of this part code.

I will do the test you said.

Best Regards,

Hamidreza

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TL431A: TL431ACDBZR