Datasheet

Transitions Between Shutdown and Playing
OutputStage
PSU
VPP
GND
IN
IN
VPP
GND
PWM
TAS5086
OUT
OUT
S0269-01
TAS5086
www.ti.com ................................................................................................................................................... SLES131C – FEBRUARY 2005 – REVISED JUNE 2008
It also has individual channel dc-blocking filters that are enabled by default.
Individual channel de-emphasis filters for 32, 44.1, and 48 kHz are included and can be enabled and disabled.
There is also a two-channel downmix result that can be output on SDOUT (I
2
S format). This result also can be
sent to the left and right front channels (channels 1 and 2) and/or to the center and subwoofer (channels 5 and 6)
as well.
A mixer on the subwoofer channel supports bass management configuration 1.
PWM output characteristics
• Up to 8 × oversampling
• 12 × at f
S
= 32 kHz, 8 × at f
S
= 48 kHz, 4 × at f
S
= 96 kHz, 2 × at f
S
= 192 kHz
• Fourth-order noise shaping
• ≥ 105-dB dynamic range, 0 – 20 kHz (TAS5086 + TAS5186 system measured at speaker terminals)
• THD < 0.06% (measured at TAS5086 outputs)
• Adjustable maximum modulation limit of 93.8% to 99.2%
The TAS5086 outputs are switching all the time with the noise shaper active. Mute is acheived by inputting a
zero into the noise shaper, with the noise shaper running and the output still switching. By using this approach,
the transitions between off and operation is avoided. The only exception is shutdown of surround channels as
described in the Surround Register (0x19) section.
Futhermore, the TAS5086 is designed to drive a load in single-ended and bridge-tied-load configurations. The
principle in the SE and BTL configurations is shown in Figure 8 and Figure 9 . In both situations, care must be
taken to ensure correct start-up sequences which charge the bootstrap capacitor and do not produce audible
artifacts; the TAS5086 is designed to do that.
Figure 8. BTL Filter Configuration
The SE configuration presents an additional challenge in order for starting up quietly. The second terminal of the
loudspeaker is connected to a split capacitor between power and ground. The advantage of this circuitly is that it
provides some degree of power-supply ripple rejection. The problem related to the split capacitor is that the
voltage over it must be controlled when the modulator starts (i.e., when the power stage output goes out of high
impedance state) to avoid a click in the speaker.
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