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SVR
Supply
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oltage
Rejection
Ratio
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f Frequency Hz
VDD = 3.6 V,
RL = 32 ,
C = 1
F
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1 k
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SVR
Supply
V
oltage
Rejection
Ratio
V
1.8 V
3 V
4.5 V
RL = 32
C = 2.2
F
f Frequency Hz
3.6 V
Decoupling Capacitors
Supply Voltage Limiting At 4.5 V
Layout Recommendations
Exposed Pad On TPA4411RTJ and TPA4411MRTJ Package Option
TPA4411RTJ and TPA441MRTJ PowerPAD Sizes
SGND and PGND Connections
SLOS430E – AUGUST 2004 – REVISED MARCH 2008
SUPPLY VOLTAGE
REJECTION RATIO
vs
FREQUENCY
Figure 74.
Figure 75.
The TPA4411 and TPA4411M are DirectPath headphone amplifiers that require adequate power supply
decoupling
to
ensure
that
the
noise
and
total
harmonic
distortion
(THD)
are
low.
A
good
low
equivalent-series-resistance (ESR) ceramic capacitor, typically 2.2 F, placed as close as possible to the device
VDD lead works best. Placing this decoupling capacitor close to the TPA4411 or TPA4411M is important for the
performance of the amplifier. For filtering lower frequency noise signals, a 10-F or greater capacitor placed near
the audio power amplifier would also help, but it is not required in most applications because of the high PSRR of
this device.
The TPA4411 and TPA4411M have a built-in charge pump which serves to generate a negative rail for the
headphone amplifier. Because the headphone amplifier operates from a positive voltage and negative voltage
supply, circuitry has been implemented to protect the devices in the amplifier from an overvoltage condition.
Once the supply is above 4.5 V, the TPA4411 and TPA4411M can shut down in an overvoltage protection mode
to prevent damage to the device. The TPA4411 and TPA4411M resume normal operation once the supply is
reduced to 4.5 V or lower.
The exposed metal pad on the TPA4411RTJ and TPA4411MRTJ packages must be soldered down to a pad on
the PCB in order to maintain reliability. The pad on the PCB should be allowed to float and not be connected to
ground or power. Connecting this pad to power or ground prevents the device from working properly because it
is connected internally to PVSS.
Both the TPA4411 and TPA4411M are available in a 4 mm
× 4mm QFN. The exposed pad on the bottom of the
package is sized differently between the two devices. The TPA4411RTJ PowerPAD is larger than the
TPA4411MRTJ PowerPAD. Please see the layout and mechanical drawings at the end of the datasheet for
proper sizing.
The SGND and PGND pins of the TPA4411 and TPA4411M must be routed separately back to the decoupling
capacitor in order to provide proper device operation. If the SGND and PGND pins are connected directly to each
other, the part functions without risk of failure, but the noise and THD performance do not meet the
specifications.
Copyright 2004–2008, Texas Instruments Incorporated
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