Operating and ASIC Temperature Clarification

[vinaym815]

@MartyG-RealSense
I have been reading the Intel® RealSenseTM Product Family D400 Series Datasheet Revision 019
October 2024 and I needed some clarification.

Q1: On page 72, Ambient Temperature range is given as 0°C - 35°C and ambient is defined as, "Ambient means environment while the camera is attached to a tripod using the camera’s tripod screw attachment and is not connected to any mechanical or thermal material".
Q1a) Does the "environment temperature" means its the temperature of the air ? Or it is some internal temperature of the camera?
Q1b) Does the ASIC temperature sensor reports this "environment temperature" ?
Q1c) Does the ASIC temperature sensor reports the temperature of Vision D4 Processor board ?

Q2: On page 72, the backside case temperature range is give as 0°C-50°C. In what kind of scenario can we end up with higher backside case temperature than "environment" temperature.

Q3: Are there any commercially available heat sinks for realsense? If not can you share some DIY projects for the same.

Thank you.

[MartyG-RealSense]

Hi @vinaym815 Thanks very much for your questions.

Q1.

ASIC refers to the Vision Processor D4 board. The ASIC temperature refers to the temperature of the board.

The ASIC temperature will primarily be the temperature of the electronic D4 V4 circuit board during operation. The more camera stream types that are enabled simultaneously, the higher the internal ASIC temperature may rise.

Q2.

The inside temperature can be affected by the outside environmental temperature. As the casing is warmed or chilled by the air environment, the inside temperature of the camera will be affected accordingly. For example, Intel lab tests once found that a camera's internal temperature should not exceed 60 degrees C if the temperature of the camera's external casing skin is not greater than 44 degrees C.

As heat radiates away from electronics, the temperature of the casing should be whatever temperature the external environment has heated it to, plus heat from the internal electronics that has not been dissipated by the heatsink.

Electronics may heat faster if the camera is being used at a location that is high above sea level, where the air in the environment is thinner. This requires cooling solutions such as fans and heatsinks to work harder to compensate. For example, a fan may be louder at a high-elevation location.

Q3.

There are not RealSense-specific heatsink solutions available. In theory, attaching a commercial heatsink to the back of a RealSense module should be straightforward so long as the heatsink guidelines in the data sheet document (on page 116 of the current October 2024 edition) are complied with.

[vinaym815]

@MartyG-RealSense Thank you for your prompt reply. I have a follow up question.

On Page 73 it is recommended to to monitor librealsense temperature readout from the application level and act upon the data if within < 5°C of the component max temperatures.
To ensure continuous operation without camera issues, the ASIC temperature should be maintained between 5°C and 45°C ?

[MartyG-RealSense]

A RealSense camera can continue to operate even when the internal temperature is high. Although the camera will continue operating, problems may start to manifest in the depth image once the temperature exceeds around 42 degrees C though. Whilst the official maximum temperature is 35 degrees, in real-world practical conditions 42 degrees could be considered to be the 'real' ideal maximum temperature.

If you use a D45x type camera such as D455 that is equipped with the thermal compensation feature then the camera can automatically adjust depth values to account for possible error resulting from temperature changes.

If you use a RealSense camera with a casing then all models except D405 are equipped with an IR Projector hardware component that can provide a Projector Temperature in addition to the ASIC temperature. The camera's firmware driver will monitor the Projector temperature and if the Projector temperature falls below 0 degrees C or rises above 60 degrees C then the camera's laser will be automatically turned off as a safety feature. The camera will continue to operate when the laser is turned off but there will likely be a reduction in depth quality, such as a greater number of empty holes in the depth image.

[vinaym815]

@MartyG-RealSense So, the 35°C and 42°C are the temperatures reported by ASIC temperature sensor and not the projector temperature sensor or an external temperature sensor ?

[MartyG-RealSense]

Both ASIC and Projector temperatures can provide a readout at the same time on cameras equipped with an IR projector component (which is located on the depth module board and not the Vision Processor D4 board) and they typically have a similar temperature value. If you only want to monitor one then I would recommend the Projector temperature as the temperature of the depth module will have a bigger effect on the images if it becomes excessive and it will indicate how close the laser is to being shut off.

You can also check the on / off status of the laser to see whether it is currently enabled or not.