Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
Subject: Re: TI's low-cost 20W "filterless" class-D amplifer IC
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Mon, 23 Dec 2002 08:21:46 -0000
NNTP-Posting-Date: Mon, 23 Dec 2002 08:21:47 GMT
Winfield Hill wrote:
> 20 watts... TI continues to improve the performance of their low-cost
> "filterless" class-D amplifer IC offerings.
> I'm impressed by the new TPA3001, a 20-watt 0.2% distortion (15W 1kHz
> 8-ohms 18V supply), no-heat-sink part in a small 24-pin TSSOP
> package. Only $2.82 qty 1k, but no inventory or samples are
> available just yet.
> If you're not familiar with it, TI's new "filterless" class D uses a
> novel modulation scheme different from most other class-D amplifiers.
> "The modulation scheme has very little loss in the load without
> a filter because the pulses are very short and the change in
> voltage is Vcc instead of 2Vcc. As the output power increases,
> the pulses widen, making the ripple current larger. Ripple
> current could be filtered with an LC filter for increased
> efficiency, but for most applications the filter is not needed."
> They do suggest a small EMI filter.
> This un-named scheme appears to differ somewhat from TI's Equibit
> "true digital" technology, however Equibit is a term that doesn't
> appear much in TI's new sales literature. Hmm...
I suppose I would call it differential PWM.
So, do you notice the "creative" specmanship. They show graphs of THD,
with 20Khz around 0.01% and 1Khz around 0.06%. Wonder how they do
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.