Junction Temperature Calculation - Texas Instruments SimpleLink CC2651R3SIPA Manual

CC2651R3SIPA
SWRS278B – FEBRUARY 2022 – REVISED AUGUST 2023

10.6 Junction Temperature Calculation

This section shows the different techniques for calculating the junction temperature under various operating
conditions. For more details, see
There are three recommended ways to derive the junction temperature from other measured temperatures:
T = ψ × P + T
1. From package temperature:
J JT case
T = ψ × P + T
2. From board temperature:
J JB board
T = R × P + T
3. From ambient temperature:
J θJA A
P is the power dissipated from the device and can be calculated by multiplying current consumption with supply
voltage. Thermal resistance coefficients are found in
Example:
Using Equation 3, the temperature difference between ambient temperature and junction temperature is
calculated. In this example, we assume a simple use case where the radio is transmitting continuously at 0 dBm
output power. Let us assume the ambient temperature is 85 °C and the supply voltage is 3 V. To calculate P, we
need to look up the current consumption for Tx at 85 °C in. From the plot, we see that the current consumption is
7.8 mA. This means that P is 7.95 mA × 3 V = 23.85 mW.
T = 48.7 × 23.85mW + T
The junction temperature is then calculated as:
°C W
J
As can be seen from the example, the junction temperature is 1.2°C higher than the ambient temperature when
running continuous Tx at 85 °C and, thus, well within the recommended operating conditions.
For various application use cases current consumption for other modules may have to be added to calculate the
appropriate power dissipation. For example, the MCU may be running simultaneously as the radio, peripheral
modules may be enabled, etc. Typically, the easiest way to find the peak current consumption, and thus the
peak power dissipation in the device, is to measure as described in
consumption.
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Semiconductor and IC Package Thermal
Section
= 1.2°C + T
A A
Product Folder Links:
Metrics.
8.8.
Measuring CC13xx and CC26xx current
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