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Tas5518 110dB dynamic range??

Jonathan Geng
Prodigy 80 points
Other Parts Discussed in Thread: TAS5518, TAS5508C

Hi folks

i was wondering if I can get some info from TI gurus regarding Tas5518.

Gone thru the data sheet in detailed and can't really figure out how the dynamic range is 110dB. Looking at the architecture it has a 32 bit pwm, true that one can have  a 32bit pwm counter but that does not necessarily gives 110dB. Can Ti gurus explain how the 110dB dynamic range is achieve? Usually pwm generated by micro controllers or dsp     PWM resolution = log((2*Tpwm)/Tcy) / log(2) = log((2*Fcy)/Fpwm) / log(2). Looking at tas5518 Evm, with a master clock in of 13.5MHz, I cannot see a 110dB achievable?

  • 0
    TI__Guru**** 189399 points

    Hi, Jonathan,

    That device is listed as NRND, which means we don't recommend it for new designs.

    We do have the TAS5508C which is the suggested replacement, but the d/s only lists 102 dB for that device. Would that work in your design?

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 80 points

    Hi Don

    thanks for the reply, sure can use 5508. Though my question remains how 102dB is achieved? If I use a TI DSP to generate PWM to drive any H bridge products for example, based on the equation above and using the following settings, at best I can get a 8 bit PWM output from any high speed TI DSP. PWM 384 KHz, DSP running at 1GHz but system clock are usually lower to be compatible to lower speed devices like SDRAM, so likely in the region of 133MHz to 266MHz. Therefore PWM resolution is at best 9.1 bit which only gives around 54dB. Therefore i still think the 5508c chip is still running at raw 8 bit pwm but would like to do d out how 102dB is derived. Thanks Don