Thermal Characteristics for SMPTE HOTLink - CY7B9235/CY7B9335
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May 19, 2009
06:16 AM
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May 19, 2009
06:16 AM
Answer: Title:
Thermal Characteristics for SMPTE HOTLink - CY7B9235/CY7B9335
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 gotten 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)
Useful Link:
CY7C9235 SMPTE-259M/DVB-ASI Scrambler/Controller (http://www.cypress.com/?rID=14213)
CY7C9335 SMPTE-259M/DVB-ASI Descrambler/Framer-Controller (http://www.cypress.com/?rID=14214)
Keywords:
HOTLink, SMPTE, CY7B9235, CY7B9335, thermal characteristics, Theta-JA, Theta-JB, Theta-JC, junction, temperature, Tj, case, board, Ta, Tb, Tc.
Thermal Characteristics for SMPTE HOTLink - CY7B9235/CY7B9335
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 gotten 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)
CY7B9235 | CY7B9335 | |||||
Part Number - | Theta-JA (°C/W) | Theta-JC (°C/W) | Tj (°C) | Theta-JA (°C/W) | Theta-JC (°C/)W | Tj (°C) |
270JC | 27 | 15 | 91.6 | 24 | 5 | 104.8 |
400JC | 27 | 15 | 91.6 | 24 | 5 | 104.8 |
Useful Link:
CY7C9235 SMPTE-259M/DVB-ASI Scrambler/Controller (http://www.cypress.com/?rID=14213)
CY7C9335 SMPTE-259M/DVB-ASI Descrambler/Framer-Controller (http://www.cypress.com/?rID=14214)
Keywords:
HOTLink, SMPTE, CY7B9235, CY7B9335, thermal characteristics, Theta-JA, Theta-JB, Theta-JC, junction, temperature, Tj, case, board, Ta, Tb, Tc.
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