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4 TAS5630B sync / heat sink questions

Baazs
Prodigy 30 points
Other Parts Discussed in Thread: TAS5630B

Hello!

I designed my PCB for TAS5630B PHD in BTL mode. PCB size: 80 x 80 mm.
I built it four times. All of them works well, without noise, best amp I ever built.

I never tried to sync them together yet.

I'd like to build an 8 channel home cinema amp with the 4 modules.

My questions:

- Is it possible to sync the 4 modules together?
/1 in master mode, 3 in slave, connect the master's OSC_IO+ output with all 3 slaves OSC_IO+ pins and IO- to IO- pins. /

- Which is the better solution: if the modules are close together on one heat sink, or use 4 heatsinks.
/ The advantage of 4 heat sink would be the amp's symmetrical design (the power supply between the modules), but the distances might cause sync problems?. /

- So can I mount the 4 modules together on 1 heat sink?
The planned placement of the PCB's and the heatsink's specification are on the picture.
The size of the heatsink is 200x200x25 mm (it's black eloxated). Can I use this heat sink, is it enough?

- "Heat sink must have a good connection to PCB ground" That's OK. But, the power pad needs to isolated / or must have good connection with the heat sink, with
silver conductive paste?
(I can't add the heatsink because of the decoupling capacitors height, so I will use a 2 mm thickness alu heat sink pad between the power pad and the heatsink)

Sorry for my english.
I hope anybody can help me.
Thank you!

  • 0
    TI__Guru**** 189401 points

    Hi, Baazs,

    Thank you for your interest in our products! Your board looks very nice!

    You can indeed use the SYNC pins to do what you propose to SYNC them together.

    As for your heat sink question... I'm not really sure which way would be better. Most of our volume customers use one heat sink for multiple parts, but, of course, they also have all the ICs mounted on the same board in a row.

    As for heat sink grease, you actually want to use insulating grease - if you use conductive grease, it has the possibility of shorting pins out on your board. Usually, there is enough metal to metal contact to transfer the ground from the heat sink (screw it to your PCB in a grounded area) to provide a good enough ground connection for the PowerPAD.

    And, remember, less heat sink grease is better! It's thermal resistance is >> metal to metal. You just want to fill the microscopic voids between the two metal pieces, not "goop" it on 3 mm thick...

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 30 points

    Hi Don!

    Thank you. 
    OK. I will sync the devices together.
    I ordered 4 smaller heatsink. So I can screw them together, but it can be separate if necessary.
    And of course, I'll use less non-conductive grease.

    Thanks for Your advice.

    Best Regards,
    Baazs.