Thermal Design <R; Deciding On Whether Particular Measures For Heat Dissipation Are Required; Estimating Tj; Estimating Power Consumption - Renesas R-IN32M4-CL2 User Manual

R-IN32M4-CL2 User's Manual: Board design edition
7. Thermal Design
This section describes the thermal characteristics of the R-IN32M4-CL2, 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-CL2 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.
7.1

Deciding on whether Particular Measures for Heat Dissipation are Required

7.1.1

Estimating Tj

Take Tj ≤ 121.7°C as the criterion for Tj of the R-IN32M4-CL2. 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)
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 0,
Power : Power consumption [W]
If Tj ≤ 121.7°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 ≤ 121.7°C is not satisfied, heat dissipation solutions are necessary.
7.1.2

Estimating Power Consumption

For the 3.3-V and 2.5-V sub-systems, estimate the power consumption from the value for current on the R-IN32M4-CL2
user's manual.
Since these are temperature dependent, the power consumption of the 1.0-V sub-systems is estimated from the following
formula according to the operating temperature.
Power (1.0-V sub-systems) = 320 + 100 × e
The list in 7.1.4, Results of Estimating Power Consumption of the 1-V Sub-Systems at Tj, gives results of estimation
under specific conditions.
R18UZ0046EJ0200
Dec. 28, 2018
<R>
(See 0,
Thermal Resistances under the JEDEC Conditions (for θja and Ψjt).)
(1.0-V sub-systems + 2.5-V sub-systems + 3.3-V sub-systems)
(0.02106×Tj)
[mW]
7. Thermal Design <R>
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