Thermal Characteristics for SMPTE HOTLink - CY7B9234/CY7B9334

Answer: Title:

Thermal Characteristics for SMPTE HOTLink - CY7B9234/CY7B9334



Questions:

- How do I calculate case temperature?

- How do I calculate board temperature?

- What is the maximum ambient temperature for HOTlink?

- What are the Theta-JA and Theta-JC values?

- What is the maximum junction temperature, Tj?



Response:

Because the thermal characteristics are dependent on the ambient temperature and power used by the system, both the equations and values are provided below.



Tj = Junction temperature

Tb = Board temperature

Ta = Ambient temperature

Tc = Case temperature



Theta-Ja = Junction to ambient thermal resistance

Theta-Jb = Junction to board thermal resistance

Theta-Jc = Junction to case thermal resistance



Pd = Power used by the device.



TEMPERATURE RANGES:

Commercial: Ta = 0 to 70 °C

Industrial: Ta= -40 to 85 °C



KNOWN VALUES

These are extracted from the table below.



JUNCTION TEMPERATURE

Tj = Theta-Ja*Power   Ta (1)



BOARD TEMPERATURE

Tj = Theta-Jb*Power   Tb (2)

so Tb = Tj - Theta-Jb*Power (3)

>From Eq(1) and (3) we get

Tb = (Theta-Ja - Theta-Jb)*Power   Ta (4)



CASE TEMPERATURE

Tc = Tj - Theta-Jc*Pd (5)

so Tc = (Theta-JA - Theta-JC)*Power   Ta (6)





                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
CY7B9234/CY7B9334 Thermal Values
 CY7B9234CY7B9334
Part Number - Theta-JA (°C/W)Theta-JC (°C/W)Tj (°C)Theta-JA (°C/W)Theta-JC (°C/)WTj (°C)
270JC603895.55532112.625
270JCT603895.55532112.625
400JC603895.55532112.625
400JCT603895.55532112.625




Useful Link:

CY7B9234/CY7B9334 SMPTE HOTLink Transmitter/Receiver (http://www.cypress.com/?rID=14216)



Keywords:

HOTLink, SMPTE, CY7B9234, CY7B9334, thermal characteristics, Theta-JA, Theta-JB, Theta-JC, junction, temperature, Tj, case, board, Ta, Tb, Tc.