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Published On: July, 2, 2025 By: Greg Sheridan | Updated: August 7, 2025 by Greg Sheridan
OSD62-PM System-in-Package (SiP) integrates the AM62x, 8Gb DDR4 or 16Gb DDR4 memory, and essential passive components into a compact 9mm x 14mm BGA package. This design simplifies the processor-to-DDR interface, reducing development complexity and time. The OSD62-PM offers the full functionality of the AM62 in a significantly smaller form factor, making it for a variety of applications, particularly those requiring compact, low-power, and high-performance processing solutions. These applications include building automation, factory automation and control, IoT gateways, edge AI, and Human-Machine Interface (HMI) among other general-purpose applications. OSD62x is also suitable for applications where low power consumption is crucial, such as portable devices, wearables, and industrial sensors.
Thermal management in small, compact, and portable semiconductor packages is critical to prevent overheating and maintain the device’s optimal performance and longevity. Overheating can lead to reduced performance, system failure, and premature device failure. Effective thermal management ensures that the device operates within its specified temperature range, preventing degradation and damage.
Figure 1: There are two device types in OSD62x-PM family, the 1GB and 2GB DDR4 options.
Small highly integrated devices present challenges due to increased heat density (power dissipation/unit volume) and limited space for cooling solutions, which in effect prevents use of heatsinks on the package. The OSD62x-PM instead dissipates most of its heat through an efficient heat transfer path from the package to the printed circuit board.
The OSD62x-PM package is 9mmx14mm Ball Grid Array (BGA) with 500 BGA balls. The substrate is made of copper rich laminate materials, with low thermal resistance making it thermally efficient. This enables heat from the silicon devices to transfer to the printed circuit board efficiently through the 500 BGA Balls. While all 500 balls take part in transferring heat to the printed circuit board, the ~100 ground and ~70 power balls are going to provide the best heat transfer. These balls allow the system designer to use continuous Cu planes in the PCB instead of individual lines or broken planes, greatly improving thermal performance quickly spreading the heat across the whole PCB.
The PCB is the primary mode of heat dissipation for the OSD62x-PM and much care should be taken in its design. The PCB directly influences the thermal performance of the OSD62x-PM. A larger PCB with solid Cu planes will have better thermal performance than a smaller PCB with small or no Cu planes.
Another factor that affects thermal performance is the presence of other heat-producing components in the vicinity of SIP. These could raise the temperature of PCB thereby reducing its effectiveness in carrying heat away from SIP.
Octavo Systems has tested the thermal performance of the OSD62x-PM on the OSD62-PM-BRK development platform and has also performed modeling to cover other cases with different power dissipation and air flow rates.
The main thermal parameter for the OSD62x-PM is θJA (Theta-JA). &thetaJA, or the junction-to-ambient thermal resistance, is defined as the temperature rise in the IC die (TJ – junction temperature) for 1 watt of power dissipation. (units are °C/ Watt). This is a useful parameter which guides system designs and helps determine chip temperature at a given power dissipation and ambient temperature. This is also a parameter to plan for adequate auxiliary cooling – either forced air or external heatsink.
There is another parameter – θJC (Theta-JC) which is often reported for IC packages. The θJC, or the thermal resistance from junction to case, is useful in cases where the majority of heat flow is via surface of the package, for example for large packages with metal lids and when there are large heatsinks attached to the package surface. This is not the case for the OSD62x-PM, as previously discussed. The OSD62x-PM uses the PCB rather than the package surface as the primary path for heat dissipation thus, we will not be discussing JC in this article.
Physical Measurements and Thermal Modeling were used to determine that θJA = ~16.9 °C/W.
An OSD6254-1G-IPM mounted on the OSD62-PM-BRK was used to measure θJA. Temperature and power measurements were taken early in the device boot sequence (before complete Linux boot) to avoid generating extra heat from the other components on the OSD62-PM-BRK. All tests were done at room temperature of 25°C.
The OSD62-PM-BRK is a 4-layer PCB with the dimensions of 1.2” x 4”. It has a minimal number of other components to support the operation of the OSD62x-PM, including power management and an oscillator.
Of the 4 layers in the OSD62-PM-BRK 2 are power and ground layers with large unbroken copper planes. (See the images below). This improves heat transfer away from the OSD62x-PM SiP.
There are two ways to determine junction temperature (TJ). First, is direct measurement using the on-chip temperature sensor in the AM62x die. Using this approach TJ was found to be between 44.8 °C – 48.6 °C. (Note: This range is due to the accuracy of the on-die temperature sensor +/- 5°C (2))
The second method is to measure the case temperature using a non-contact temperature sensor and approximate the junction temperature. Using this method, for example FLIR camera, the junction temperature is within a degree of case temperature, TC = 44.7 °C
The power measurement was taken from the power supply feeding the OSD62-PM-BRK. It was measured at the same time the temperature was taken. It was found to be 1.4W.
TJ (max) = Die temperature as measured by on-chip sensor = 48.6 °C
TA = 25 °C
P = 1.4 W
θJA = (TJ – TA) /P
θJA = (48.6 – 25)/1.4 = 16.9 °C/W
We also modeled the OSD62x-PM because it is not practical to test all expected application cases. Finite element models were constructed to calculate thermal resistance of package. Results for the Theta-ja on a high conductivity JEDEC PCB, with and without airflow are given below.
Figure 11 – Finite Element Model: (a) SIP on PCB; (b) With mold compound removed for visibility
The results of the two use cases with the OSD62x-PM consuming 1W of power is shown below. Case 1 is in Still Air and Case 2 has an airflow of 1m/s.
As seen, there is good agreement in value of ?JA that was determined using actual measurement and models.
| Revision Number | Revision Date | Changes | Author |
|---|---|---|---|
| 1 | 08/07/2025 | Initial Revision | Masood Murtuza |
There has been multiple revisions to the OSDZU3-REF and some of the documentation is for specific revisions.
The revision of your OSDZU3-REF is printed under the fan next to the Octavo Systems logo. See the image below.
If there are multiple versions of a document make sure you select the one that matches your revision.
