TPA3100D2_17 Datasheet, PDF (26/41 Pages) Texas Instruments – 20-W STEREO CLASS-D AUDIO POWER AMPLIFIER

TPA3100D2
SLOS469F – OCTOBER 2005 – REVISED AUGUST 2010
www.ti.com
THERMAL PROTECTION
Thermal protection on the TPA3100D2 prevents damage to the device when the internal die temperature
exceeds 150°C. There is a ±15°C tolerance on this trip point from device to device. Once the die temperature
exceeds the thermal set point, the device enters into the shutdown state and the outputs are disabled. This is not
a latched fault. The thermal fault is cleared once the temperature of the die is reduced by 30°C. The device
begins normal operation at this point with no external system interaction.
PRINTED-CIRCUIT BOARD (PCB) LAYOUT
Because the TPA3100D2 is a class-D amplifier that switches at a high frequency, the layout of the printed-circuit
board (PCB) should be optimized according to the following guidelines for the best possible performance.
• Decoupling capacitors—The high-frequency 1µF decoupling capacitors should be placed as close to the
PVCC (pins 26, 27, 34, and 35) and AVCC (pin 48) terminals as possible. The VBYP (pin 16) capacitor,
VREG (pin 15) capacitor, and VCLAMP (pins 30 and 31) capacitor should also be placed as close to the
device as possible. Large (220 µF or greater) bulk power supply decoupling capacitors should be placed near
the TPA3100D2 on the PVCCL, PVCCR, and AVCC terminals.
• Grounding—The AVCC (pin 48) decoupling capacitor, VREG (pin 15) capacitor, VBYP (pin 16) capacitor, and
ROSC (pin 14) resistor should each be grounded to analog ground (AGND, pin 17). The PVCC decoupling
capacitors and VCLAMP capacitors should each be grounded to power ground (PGND, pins 28, 29, 32, and
33). Analog ground and power ground should be connected at the thermal pad, which should be used as a
central ground connection or star ground for the TPA3100D2.
• Output filter—The ferrite EMI filter (Figure 29) should be placed as close to the output terminals as possible
for the best EMI performance. The LC filter (Figure 27 and Figure 28) should be placed close to the outputs.
The capacitors used in both the ferrite and LC filters should be grounded to power ground. If both filters are
used, the LC filter should be placed first, following the outputs.
• Thermal Pad—The thermal pad must be soldered to the PCB for proper thermal performance and optimal
reliability. The dimensions of the thermal pad and thermal land should be 5,1 mm by 5,1 mm. Five rows of
solid vias (five vias per row, 0,3302 mm or 13 mils diameter) should be equally spaced underneath the
thermal land. The vias should connect to a solid copper plane, either on an internal layer or on the bottom
layer of the PCB. The vias must be solid vias, not thermal relief or webbed vias. See TI Technical Briefs
SCBA017D and SLUA271 for more information about using the QFN thermal pad. See TI Technical Briefs
SLMA002 for more information about using the HTQFP thermal pad. For recommended PCB footprints, see
figures at the end of this data sheet.
For an example layout, see the TPA3100D2 Evaluation Module (TPA3100D2EVM) User Manual, (SLOU179).
Both the EVM user manual and the thermal pad application note are available on the TI Web site at
http://www.ti.com.
BASIC MEASUREMENT SYSTEM
This application note focuses on methods that use the basic equipment listed below:
• Audio analyzer or spectrum analyzer
• Digital multimeter (DMM)
• Oscilloscope
• Twisted-pair wires
• Signal generator
• Power resistor(s)
• Linear regulated power supply
• Filter components
• EVM or other complete audio circuit
Figure 35 shows the block diagrams of basic measurement systems for class-AB and class-D amplifiers. A sine
wave is normally used as the input signal because it consists of the fundamental frequency only (no other
harmonics are present). An analyzer is then connected to the APA output to measure the voltage output. The
analyzer must be capable of measuring the entire audio bandwidth. A regulated dc power supply is used to
reduce the noise and distortion injected into the APA through the power pins. A System Two audio measurement
system (AP-II) (Reference 1) by Audio Precision includes the signal generator and analyzer in one package.
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