IWR6843AOPEVM: Executing "68xx AoP_ODS - Multiple Gesture and Motion Detection" in a small cabinet.

Hideaki Nambu

Mastermind 9165 points

Part Number: IWR6843AOPEVM

Hello,

Please forgive a long message.

I would like to evaluate the gesture sample code under a simulated final product condition.

Could you please advise how to realize a hardware, like its cabinet and heatsink ?

I would like to do:

Execute the gesture sample code with no modifications. (C:\ti\mmwave_industrial_toolbox_4_3_2\labs\gesture_recognition\68xx_multi_gesture_and_motion_det\prebuilt_binaries\aop\multi_gesture_demo_68xx_aop.bin)
The IWR6843AOPEVM Rev.F to be broken to use just the Mission board side.
Put the EVM in a reasonably smaller cabinet. (A heatsink could be added inside or outside the case.)

Could you please advise how can we satisfy the three above ?

I tried to break my question to the following three:
Q1. The power dissipation to be mitigated.
Q2. Thermal performance value which is required to cool the board
Q3. A practical configuration of heat sink and a cabinet to realize the thermal performance.

Let me explain my progress:

Q1. The power dissipation to be mitigated.

I found some candidate of possible power dissipation values. Here I would like to ask the latest recommendation.
SWRA672.pdf tells its duty is approx. 25% (page16) and the 25% duty power dissipation is 1.2589W for IWR part or 1.6838W for PCB total (page7). I think Rja was brought from 1.2589W:
Rja = (Tj-Ta)/P = (105.1 - 25) / 1.2589 = 63.627
On the other hand, in the previous thread, I had a reply "higher than 25%". TI might recommend a higher or latest value for the power dissipation.
So the power dissipation value, to be mitigated, would be 1.2589W, 1.6838W, or a new value.

Q2. Thermal performance value which is required to cool the board

Let me confirm my understanding. I think it is determined from the given conditions, in this case the the power dissipation and the board thermal performance.
The power dissipation comes from the Q1 conclusion.
And a good value for the board thermal performance would be (9.8 degC/W), but let me reconfirm.
The value comes from SWRA672.pdf, page-7, Table2, Psi-jb for Mission section PCB.
Here let me confirm if the value is good for Rev.F board. Because the Rev.F mission board PCB area is not 540mm2 but 580mm2 (Edit: not 580mm2 but 540mm2), therefore a good value for the Rev.F mission board would be larger than 9.8.
Also can I ask the value assumes no-heatsink ?

Q3. A practical configuration of heat sink and a cabinet to realize the thermal performance.

Can I ask your advice about a typical configuration of the heat sink and the cabinet ?
Do you think if it is practically possible to put the heatsink in a smaller cabinet?
The SWRA672.pdf doesn't cover cabinets, your advice is highly appreciated.

over 5 years ago

0 CHETHAN KUMAR Y.B. over 5 years ago

TI__Mastermind 25835 points

Hello Hideaki,

Thank you for detailed questions,

Do you have a rough product goal/condition in terms of size of the PCB, Size of enclosure, Enclosure type, metal or plastic etc..? Give us couple of days to address above questions.

Thanks and regards,

CHETHAN KUMAR Y.B.

0 Hideaki Nambu over 5 years ago in reply to CHETHAN KUMAR Y.B.

Mastermind 9165 points

Chethan,

I appreciate your cooperation.

>>>

Do you have a rough product goal/condition in terms of size of the PCB, Size of enclosure, Enclosure type, metal or plastic etc..? Give us couple of days to address above questions.

<<<

>> Rough product goal/condition in terms of size of the PCB:

It is 15mm * 36mm = 540 mm2.

We use the mission side of the IWR6843AOPEVM Rev.F.

>> Size of enclosure, Enclosure type, metal or plastic etc..?

None of strict requirements for them.

For the size, it is preferable not much larger than the mission board, 15mm*36mm.

For the enclosure type:

[1: Heatsink in the enclosure]: as long as I know a plastic or a polycarbonate would be good for heat, radio, and price. Easy to make holes.

[2: Heatsink outside the enclosure]: I'm sorry but I have no idea. Also no findings of cataloged enclosure products.

Once I was interested in Takachi DPCP050504T (55*53*36mm) until I found the heat. The DPCP series has the following Pros:

- Made of Polycarbonate. The box accepts 75degC.

- The part# -T means a transparent box lid. Which shows the nice small PCB and IWR in the enclosure.

- Accpepts screws with special star-shaped head. We can seal the box and have a radio certification.

DPCP050504T -- https://www.takachi-el.co.jp/assets/attachments/images/DPCP050504T_20191001144649.pdf

A list of Takachi DPCP series -- https://us.misumi-ec.com/vona2/detail/222000227759/

We would like to build an enclosure example.

Execute the gesture sample code with no modifications. (C:\ti\mmwave_industrial_toolbox_4_3_2\labs\gesture_recognition\68xx_multi_gesture_and_motion_det\prebuilt_binaries\aop\multi_gesture_demo_68xx_aop.bin)
The IWR6843AOPEVM Rev.F to be broken to use just the Mission board side.
Put the EVM in a reasonably smaller cabinet. (A heatsink could be added inside or outside the case.)
Seal the box lid and have a radio certification.

0 CHETHAN KUMAR Y.B. over 5 years ago in reply to Hideaki Nambu

TI__Mastermind 25835 points

Hello Hideaki Nambu-san,

Thank you for providing the additional details on the PCB, Size of enclosure, Enclosure type...

Please find the answers to the previous questions.

Q1. The power dissipation to be mitigated.

>> Lowering the Power dissipation at system level reduces junction temperature. Some trade-off could be explored what would be minimum duty-cycle with which demo could be run with little amount of performance degradation.

In this specific example Rja is based on the 1.2589W Power dissipation of the mmWave chip. 1.6838W power is dissipated on the whole board. If you reduce the duty-cycle (lower than 25%) of the operation then power dissipation on the chip will reduce also power dissipation of the board also reduces as power dissipation of the PMIC also reduces together.

Q2. Thermal performance value which is required to cool the board

>> Yes board size is 540mm2, thermal simulations were done on actual board size. Hence as you rightly pointed out a good value for the board thermal performance would be (9.8 degC/W) Yes, In these thermal simulations assumed no heatsink.

Q3. A practical configuration of heat sink and a cabinet to realize the thermal performance.

>> If the PCB size is 540mm2 and 25% Duty-cycle then good heatsink is a must.

Below is an example of Fin based heat sink developed for the previous version of AOP hardware. Care need to be taken not to obstruct the Antenna field of view while providing the heatsink options.