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R-IN32M4-CL3 User's Manual: Board design edition
8.
Thermal Design
This section describes the thermal characteristics of the R-IN32M4-CL3, and includes notes that require attention in the
design of the board on which the device is mounted in terms of the dissipation of heat and the prevention of abnormal
heating. Since the R-IN32M4-CL3 incorporates a Gigabit Ethernet PHY module and large-capacity memory, it requires
greater consideration of heat than most devices.
Design the board and casing in consideration of heat dissipation.
8.1
Deciding on whether Particular Measures for Heat Dissipation are Required
8.1.1
Estimating Tj
Take Tj ≤ 125°C as the criterion for Tj of the R-IN32M4-CL3. Estimate Tj from the following formulae.
Tj = Tt + Ψjt x power or Tj = Ta + θja x power
Tj:
Junction temperature [°C]
Tt:
Package surface temperature [°C]
Ta:
Ambient temperature [°C]
θja:
Thermal resistance [°C/W] between the junction (at temperature Tj) and the ambient environment (at Ta)
(See 8.1.3, Thermal Resistances under the JEDEC Conditions (for θja and Ψjt).)
Ψjt:
Thermal resistance [°C/W] between the junction (at temperature Tj) and the surface of the package (at Tt)
(See 8.1.3, Thermal Resistances under the JEDEC Conditions (for θja and Ψjt).)
Power: Power dissipation [W]
(1.15-V sub-systems + 2.5-V sub-systems + 3.3-V sub-systems)
If Tj ≤ 125°C is satisfied, the semiconductor device does not require further measures for heat dissipation.
However, if the semiconductor device is to be installed in ways that have varying criteria for determining increases in
temperature, prepare measures for heat dissipation as required.
If Tj ≤ 125°C is not satisfied, heat dissipation solutions are necessary.
8.1.2
Estimating Power Consumption
For the 3.3-V, 2.5-V, and 1.15-V sub-systems, estimate the power consumption from the value for current on the R-
IN32M4-CL3 user's manual.
Thermal Resistances under the JEDEC Conditions (for θja and Ψjt)
8.1.3
The thermal resistances under the JEDEC-2S2P conditions are as follows.
However, these values are for the devices alone; care is required since the actual thermal resistances will depend on the
board, casing, and peripheral components.
R-IN32M4-CL3, 23 mm Square BGA Package
R-IN32M4-CL3, 17 mm Square BGA Package
The thermal resistance value θja of R-IN32M4-CL3 varies depending on the mounting board, housing, and peripheral
components.
If there are criteria for increases in temperature (Δt = Tt - Ta) as a final product, prepare measures to obtain θja that
achieves the target Δt, referring to section 8.2, Examples of Measures for Heat Dissipation.
R18UZ0074EJ0100
Dec 24, 2019
θja [°C/W]
19.8
20.6
8. Thermal Design
Ψjt [°C/W]
0.35
0.36
Page 26 of 61
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