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TPA3111D1 shutdown problem

Morris Oxford
Prodigy 10 points
Other Parts Discussed in Thread: TPA3111D1

Hi,

I am using the TPA3111D1 to drive a predominantly inductive load. The TPA3111D1 is fed from a pre-amp containing an automatic gain control (AGC) so when a burst of input signal is applied a large signal is fed to the TPA for a short period (5-10ms) until the AGC has stabilised. Under these conditions the unit shuts down temporarily then comes back on (-SD and -FAULT are linked for auto-recovery).

From the data sheet  it would suggest this is the short circuit protection acting as it recovers (unlike the DC protection). The problem is it only does it with high frequency bursts which with an inductive (high impedance at high frequency) load gives high voltage low current. At lower frequencies (and therefore higher currents) the problem does not happen.

Is there anything else that could trigger this response other than the short circuit protection or is there any way of disabling it?

Regards,

Bruce.

  • 0
    TI__Mastermind 37045 points

    Hello Bruce,

    It sounds like the it is caused by over current condition. There is no way of disabling the over current protection function. Are you using the EVM with LC filter for your inductive load? When designing the LC filter, the load must be taken into account. If the filter is not designed properly, there maybe peaking at near the cut off frequency which can cause OC.  Attached is an app note on LC filter design which explains how peaking can trigger OC or short circuit protection circuitry.

     

    reg,

    Paul.

    sloa119a[1].pdf