RC4558: Thermal Resistance

Brian Wang0928

Genius 11650 points

Part Number: RC4558

Could you offer the R_{θJC and}Tc_(Max)?

In the d/s, there are only T_A、T_J、R_{θJA, they are not enough for thermal calculation.}

Regards

Brian W

over 3 years ago

0 Ron Michallick over 3 years ago

TI__Guru*** 140106 points

Brian,

Which package or two packages do they need data?

If they are using RθJC parameter then they are using a contact heat sink or they are planning to use the RθJC parameter incorrectly.

https://www.ti.com/lit/pdf/sbva025

0 Brian Wang0928 over 3 years ago in reply to Ron Michallick

TI__Genius 11650 points

Hi Ron,

Thanks. The package type is RC4558IPWR. There is no heaksink on the top of device attached in application. What temperature point RD can be easily obtained are T_case and T_ambient.

Pls offer the Theta_jc in advance. We will also communicate the correct measurements of the junction temp with SMD package. However in the d/s, I don’t even find the thermal metrics that is independent with pcb size!

0 Ron Michallick over 3 years ago in reply to Brian Wang0928

TI__Guru*** 140106 points

Brian,

Theta JC, top 67.1 C/W
Theta JB 112.5 C/W
Psi JT 8.4 C/W
Psi JB 110.7 C/W

If they know the top of case temperature (T) then they can estimate the die temperature (D) as D = T + [Psi JT] * [power dissipation].

The Theta JC value is nearly useless because the majority of the heat does not escape through the device top; actually very little does. That is why the top of case temperature is nearly as hot as the die.

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RC4558: Thermal Resistance