LMV722-N: LMV722-N Θj-c

Hello Yamamoto-san, 

It looks like in this older device this information is not available. The Semiconductor and Thermal IC Metrics document has many formulas, maybe it will help you solve the issue using only theta-j-a. 

If not, we may recommend a newer device that has the theta-j-c information and also solves your application requirements. 

All the best,
Carolina

Hello Yamamoto-san, 

Θj-c is only useful if you plan to attach a heatsink to the device. In a normal (not heat sink) very little heat flows out of the top of the package. 

Section 3 of the app note meations ΨJT, Junction to Top of Package parameter (far more useful)

Do you have a full part number?

Thanks for the reply.
The product name is LMV722MMX/NOPB and the PKG is VSSOP.

【Θj-c is only useful if you plan to attach a heatsink to the device. In a normal (not heat sink) very little heat flows out of the top of the package. 】

　→So, can I assume that Tj=Tc?

If you look at page 8 of The Semiconductor and Thermal IC Metrics, you will see that the package in general is listed as θj-c＝4～15℃/W.
Does this mean that if Tj calculated at 15°C/W is less than 85°C, it is safe to use?

Hello Yamamoto-san, 

If the board is already built, the best way to determine internal die temperature, it to use this equation 

Tc is the measured top of case temperature.  Power ([VCC+] - [VCC-]) * ICC plus power based on output current for amplifiers.

If op amp is sourcing current, then power is  ([VCC+]-VOUT) * IOUT

If op amp is sinking current, then power is  (VOUT-[VCC-]) * IOUT

I requested a thermal mode to be made for LMV722MMX/NOPB. This will take 2 to 14 days to be completed. 

I expect the ΨJT will be roughly 13 C/W (based on a similar device / package)

Hi Ron-san,

We are in serious trouble and need the results of the simulation as soon as possible.

I'm sorry to rush you, but I need an answer ASAP.

Hey Yamamoto-san, 

I have reached out to the thermal model engineer to see how much longer. 

All the best,
Carolina 

Hello Yamamoto-san, 

The modeling team has confirmed that the model will be ready by 7/14. 
They are trying to complete it as quickly as possible, so it might be sooner, but this was the confirmed date. 

All the best,
Carolina

Hi Carolina,

Thanks for checking.
I'll be waiting for your reply.

B/R

Yamamoto