UC2825A: UC2825ADW

Hi Gulnihal,

Attached you can see the temperature range of the device to operate (Section 6 of Datasheet). These are the maximum operating temperature ranges. if the device has been exposed to values close or beyond these limits, it would have been damaged. 

If you have any further questions, let me know replying to this thread.

We operated around - 5 degree , it is not close to the maximum operating temperature. 

Hi,

Did you try a new unit to see if work ?

Please provide your schematics for review.

We tried different units. The result is the same.  Our device's output voltage is 13,8 V;  current is 22 A.  our device was passed from the general test and heat tests.  Our cold test is 4 hours at -30 degrees.  The device operates in normal conditions voltage is 13.8 V, when the device draws current,  voltage decreases to 26 V or  0. We used UC3825DW in this device. we replaced from UC3825DW to UC2825ADW. We did not this fault when we used UC3825DW. This happened with UC2825ADW.

Hi,

UC3825DW temperature range is 0 to 70C so cannot be used to negative temperature.

Your message is confusing: where suddenly jump out 26V?

"The device operates in normal conditions voltage is 13.8 V, when the device draws current,  voltage decreases to 26 V or  0." 

Did you mean -30C made your converter output to 26V from 13.8V then to 0 V?

Can you review your message and re-send it? I cannot understand your message.

Also, please provide your schematics.

 The device was increased to 26V when it was removed from cold.

"We mean that the voltage of some devices is 26 volt some of them 0.  The fault was changed from device to device around -5 degrees. I have attached schematic 

Hi Gulnihal. I am taking care of this thread, and I will answer your question soon today. 

Hi Gulnihal,

Would you please show the full schematic of your converter? What is inverting input of the E/A (pin6 of pin header)? I can notice that the output of the E/A is connected to pin5 of the pin header. What is that connection? It might be that at low temperatures the input bias current, input offset current and offset voltage are affecting the output of the E/A, but I need to check those pin connections first.