TAS5111
SLES049D JULY 2003 REVISED MARCH 2004
www.ti.com
14
As an indication of the importance of keeping the thermal
grease layer thin, if the thermal grease layer increases to
0.002 inches thick, the required heatsink thermal
resistance changes to 2.4
°C/W.
Thermal
Pad
3,91 mm
3,31 mm
4,11 mm
3,35 mm
CLICK AND POP REDUCTION
Going from nonswitching to switching operation causes a
spectral energy burst to occur within the audio bandwidth,
which is heard in the speaker as an audible click, for
instance, after having asserted RESET LH during a
system start-up.
To make this system work properly, the following design
rules must be followed when using the TAS5111 back end:
D The relative timing between the PWM_AP/M_x
signals and their corresponding VALID_x signal
should not be skewed by inserting delays,
because this increases the audible amplitude
level of the click.
D The output stage must start switching from a
fully discharged output filter capacitor. Because
the output stage prior to operation is in the
high-impedance state, this is done by having a
passive pulldown resistor on each speaker
output
to
GND
(see
Typical
System
Configuration).
Other things that can affect the audible click level:
D The spectrum of the click seems to follow the
speaker impedance vs. frequency curve—the
higher the impedance, the higher the click
energy.
D Crossover filters used between woofer and
tweeter in a speaker can have high impedance
in the audio band, which should be avoided if
possible.
Another way to look at it is that the speaker impulse
response is a major contributor to how the click energy is
shaped in the audio band and how audible the click is.
The following mode transitions feature click and pop
reduction.
STATE
CLICK AND
POP REDUCED
Normal(1)
→ Mute
Yes
Mute
→ Normal(1)
Yes
Normal(1)
→
Error recovery
(ERRCVY)
Yes
Error recovery
→ Normal(1)
Yes
Normal(1)
→ Hard Reset
No
Hard Reset
→ Normal(1)
Yes
(1) Normal = switching
REFERENCES
1.
TAS5000 Digital Audio PWM Processor data
manual—TI (SLAS270)
2.
True Digital Audio Amplifier TAS5001 Digital Audio
PWM Processor data sheet—TI (SLES009)
3.
True Digital Audio Amplifier TAS5010 Digital Audio
PWM Processor data sheet—TI (SLAS328)
4.
True Digital Audio Amplifier TAS5012 Digital Audio
PWM Processor data sheet—TI (SLES006)
5.
TAS5026
Six-Channel
Digital
Audio
PWM
Processor data manual—TI (SLES041)
6.
TAS5036A
Six-Channel
Digital
Audio
PWM
Processor data manual—TI (SLES061)
7.
TAS3103 Digital Audio Processor With 3D Effects
data manual—TI (SLES038)
8.
Digital Audio Measurements application report—TI
(SLAA114)
9.
PowerPAD
Thermally
Enhanced
Package
technical brief—TI (SLMA002)
10. System Design Considerations for True Digital
Audio Power Amplifiers application report—TI
(SLAA117)