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−100

−90

−80

−70

−60

−50

−40

−30

−20

−10

0

10

100

1 k

10 k

100 k

f − Frequency − Hz

C = 1

µF

−100

−90

−80

−70

−60

−50

−40

−30

−20

−10

0

10

100

1 k

10 k

100 k

1.8 V

3 V

4.5 V

C = 2.2

µF

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

TPA4411

TPA4411M

SLOS430E – AUGUST 2004 – REVISED MARCH 2008

SUPPLY VOLTAGE

SUPPLY VOLTAGE

REJECTION RATIO

REJECTION RATIO

vs

vs

FREQUENCY

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 µF, placed as close as possible to the device

performance of the amplifier. For filtering lower frequency noise signals, a 10-µF 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

19

Product Folder Link(s): TPA4411 TPA4411M