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TAS5630 vs TAS5630B

Other Parts Discussed in Thread: TAS5630, TAS5630B

We ave been evaluating the TAS5630.

 We are just about to move this to the next step (PCB layout) when I noticed that the TAS5630 has been replaced by the "exact equivalent"  TAS5630B. see http://www.ti.com/product/tas5630.  

Looking that the specs shows they are anything but exact equivalents. e.g. the "B" will only tolerate down to a 3 ohm load in PBTL mode.

Some further information would be helpful

  • Hi Nick,

    TAS5630B has improved DC offset, THD and ruggedness. The new min load spec for PBTL is to make it more robust and reliable across various different PCB layout/designs by our customers.

     

    reg,

    Paul.

    Applications Engineer. 

  • Hi Paul,

    If the offset, ruggedness and THD are the only differences and are you saying that it is OK to use with a 2 ohm load in PBTL? 

    Thanks,

    NB

  • Hi Nick,

    The 2 ohms min load spec need to be followed to avoid potential issue. However, you maybe able to operate with 2R load at a lower PVDD and/or with schottky diodes (such as 30BQ060) at PWM output pins to GND. However, we can not guarantee anything outside the datasheet.

     

     

    reg,

    Paul.

     

  • Hi, Nick,

    Allow me to elaborate a little on Paul's response.

    AFAIK, nothing was changed that would affect the power and load driving capability. What we found is in order to drive super low impedances, you have to be very careful. Under optimal conditions, it can work, but we rarely see customers who can implement systems with optimal conditions (you guys always need to make trade-offs) so in order to more realistically spec the part for typical customer systems, we derated its capability listed on the d/s.

    -d2

  • Thanks Don - that was most informative.

    I really think that we need a better understanding of exactly what the limitations are. Also, the load is not going to be purely resistive ( they never are!). In my application the load will be a long way off this ideal.

    I am not at liberty to disclose any more in a public forum.

    NB 

  • ** BUMP **

    Any more info?

    What, exactly are the issues, aside from the obvious current and thermal ones, that need to be addressed when using PBTL mode on a  TAS5630B when driving a 2 ohm load?

     What about when driving a complex (capacitive load)?

    NB

  • Hi Nick, I think the best chance of success would be just follow the EVM layout and leave pads for the schottky diodes on the PWM output pins in case they are needed to provide extra protection. For complex/capacitive loads, you may want to size the LC filter accordingly to ensure that there is not too much peaking during operation. Also it might be a good idea to add some low cost didoes after the LC filter (PVDD and GND) to clamp any excessive peaking voltage due to the complex load. Most of the issues we have seem are due to poor PCB layout that did not follow the guidelines. reg, Paul.
  • Thx, Paul.

    I have enough to move on... to my next question.

    -Nick