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TL431A-Q1: Load Dump issue

Nicky Lim
Genius 3195 points

Part Number: TL431A-Q1

Hello,

Question about Load Dump issue.

 

1. Regulator Max operating voltage = 40V​

2. Operating voltage = 18~32V

3. Operating current = 25mA

​4. Load dump voltage = 174V(5ms @ 1pulse, 350ms)

 

To meet above spec, will use TVS diode with Clamping Voltage is one of 50V, 53V and 58V. 

Can TL431AQDBZRQ1 be operated with above condition?

 Max Operating Voltage of TL431AQDBZRQ1 is described as 40V in datasheet, but above spec is Load dump condition, not continuous condition. 

 

Please check and let me get your answer ASAP.

 

Regards,

Nicky

 

  • 0
    TI__Mastermind 19370 points
    Hi Nicky,


    The biggest issue I see is that this device will not work in the conditions that were provided. The main 2 issues are voltage and thermal temperature.

    1. Voltage: I would not recommend using the part above its absolute maximum voltage rating as the device will be stressed and possibly have permanent damage over time.

    2. Thermal: The current is too high for the voltage that is being regulated. For example if you are using this device at 18V with 25mA, that is almost 0.5W. With its thermal resistance if 334 C/W, the device will heat up at least 150C above its regular temperature which will push the device above its operating temperature range. This will cause the device to shutdown.

    -MZ