LMV431A: LMV431A derating above 85°C

Bastian Scheidt

Part Number: LMV431A
Other Parts Discussed in Thread: LM4041-N

Hello,

I use LMV431A in one of our designs and am not sure about maximum case temperature for this device. Maximum power dissipation for this device is in my specific case 40 mW, so far below the maximum allowed dissipation for SOT23-3 case. But I measure 86 degree on the surface of the device.

The derating curve tells me "if there is a temperature higher 85°C, we guarantee for nothing." Am I right here? Or is it possible to ignore this graph and run with a derating of 2.2mW/°C for my case ?

Thanks in advance!

Best regards,

Bastian S.

over 3 years ago

0 Ben C over 3 years ago

TI__Mastermind 39615 points

Hi Bastian,

Are you measuring the case temperature at 25C ambient temp or is the ambient temp of the device at +85C? Based on the information you provided, the device is under the SOT-23 derating curve which is good. The operational temperature for the LMV431A is -40C to +85C ambient.

Ben

0 Bastian Scheidt over 3 years ago in reply to Ben C

Prodigy 40 points

Hi Ben,

I measure the temperature of the device directly on the case with a small thermocouple sensor. The device is mounted on a PCB with lots of other components in a housing tested at 60°C in a thermal chamber. The themocouple sensor measures 86°C and is thermally connected to the case via thermal paste.

So I know, that the case temperature is already at 86°C, with 40mW losses and calculated with a Rthja of 455 °C/W (this is conservative, Rthjc would be smaller) I would have a junction temperature of ca. 105°C which would be ok, if I consider comment (2) in 7.4 of your datasheet.

But as already meantioned, the REcommended Operationg Conditions say no to anything greater 85°C for my understanding.

Bastian

0 Ben C over 3 years ago in reply to Bastian Scheidt

TI__Mastermind 39615 points

Hi Bastian,

Have you looked into the TLVH431-Q1 product? The temp range is -40C to 125C. Also, there is the LM4041-N which has a temp range of also -40C to +125C.

Ben

0 Bastian Scheidt over 3 years ago in reply to Ben C

Prodigy 40 points

Hi Ben,

Thanks for supporting with different products! If possible I would like not to change the part here.

You say "The operational temperature for the LMV431A is -40C to +85C ambient" but these values are corresponding to a test setup described in JEDEC JESD51-2a right ? Is there a good application note available how to take the temperature values into account?

Best regards,

Bastian

+1 Ben C over 3 years ago in reply to Bastian Scheidt

TI__Mastermind 39615 points

Hi Bastian,

THe LMV431A was designed to operate within the ambient temp range of -40C to +85C. For example, the VREF voltage is tested at full temp range. See below: