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TPA3106D1: How many Slaves to a Master

Lindsey Fike
Intellectual 2170 points
Part Number: TPA3106D1

Hello, 

How many slaves can be be daisy chained via a sync line to all slaves? 

I have a customer that is running 1 master and 9 slaves and they have looked at the sync line with a scope and it's badly rounded on the rising edge. They haven't noticed any audible artifacts yet (not enough audio testing to say). 

The datasheet says nothing about how many slaves can be attached.  It only says that the drive capability has been greatly improved.

Thanks!

  • 0
    TI__Genius 9140 points

    Fike,

    Usually the datasheet doesn't specify how many slave can used for one master. The logic output pin has limited current souring capability of ~20mA, and input pin has some capacitance, which limit that. Suggest your customer to add buffer to enable larger current capability.

    Dylan

  • 0 in reply to Dylan Yao
    TI__Intellectual 2170 points

    Hey Dylan, 

    Apologies- I had PTO that got in the way of this reply. 

    First- can we recommend a part for the customer. They at least need to know the pin capacitance to design something. Something that's a single SOT23-ish package capable of driving 9x mystery capacitance at 200-300kHz. 

    I had a look through the datasheet and didn't see that 20mA current source capability listed anywhere. Where did that number come from?

    And I don't see an input capacitance for the sync pin either.

    The only specs I could find for the sync pin are the

    Absolute Maximum Ratings:

    Input voltage:  –0.3 V to VREG + 0.5 V

    Recommended Operating Conditions:

    High-level input voltage   2V max

    Low-level input voltage:   0.8V min

    High-level input current:  2A max

    Low-level input current:   1A max

    Those input currents look like mistakes to me (2A?), unless they are supposed to be quantified with a time limit...

    Thanks for the support! 

  • 0 in reply to Lindsey Fike
    TI__Mastermind 19030 points

    Hi Lindsey,

    I am sorry. In fact, we did not evaluate how many slave devices can be support for one master.

    We do suggest that customer can add buffer to make sure the sync signal integrity.

    Sync pin High-level input current is 2uA max. 

    Regards,

    Derek