TL431LI-Q1: Application Question

Hi Lanxi,

Lanxi Li said:

1) The output is 2.5V. Does TL431 have any requirements for the voltage drop between input and output? What is the minimum input?

The minimum input (cathode) voltage is the output (reference) voltage, and the input voltage can go as high as 36V.

Lanxi Li said:

2) Is there a minimum current limit for the size of the output load? My current minimum situation may only be 35uA

The only limit on the output current (reference input current) is the absolute maximum ratings of min -5mA and max 10mA, so as not to cause damage to the device.

Thanks,

Joshua

Joshua,

About the second question, there is a request said 0.6mA -- IKA, does this related to the output current? (Customer is only 35uA)

Also, please help review the SCH as below:

Vin =3.3V, Vout = 2.5V, I load range = 35uA--2mA.

Their main concern is when the load is quite small, whether the output of TL431 is stable? 

Best regards,

Lanxi

Hi Lanxi,

The 0.6mA IKA is related to the output current and going below that minimum would lead to inaccurate voltage regulation. We have our ATL431LI-Q1 shunt regulators that operate at a much lower 80 uA IKA voltage, the oderable part number is ATL431LIAQDBZRQ1. This would still require an increase in current from customer standpoint of 35uA.

Thanks,
Joshua 

Joshua,

So from your speaking, the Imin is only related to accuracy issue, any other influence here.

Do you have any accuracy data when IKA is lower than 80uA?

Increase the current is one solution, but on other hand, customer can also evaluate whether they can accept the accuracy decrease with 35uA.

Thank you so much.

Best regards,

Lanxi