THERMAL PROTECTION
PRINTED-CIRCUIT BOARD (PCB) LAYOUT
SLOS578 – MAY 2008
........................................................................................................................................................................................................
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Thermal protection on the TPA3124D2 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.
Because the TPA3124D2 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 0.1-
µ
F decoupling capacitors should be placed as close to the
PVCC (pins 1, 3, 10, and 12) and AVCC (pins 19 and 20) terminals as possible. The VBYP (pin 7) capacitor
and VCLAMP (pin 11) capacitor should also be placed as close to the device as possible. Large (220-
µ
F or
greater) bulk power-supply decoupling capacitors should be placed near the TPA3124D2 on the PVCCL and
PVCCR terminals.
•
Grounding—The AVCC (pins 19 and 20) decoupling capacitor and VBYP (pin 7) capacitor should each be
grounded to analog ground (AGND, pins 8 and 9). The PVCCx decoupling capacitors and VCLAMP
capacitors should each be grounded to power ground (PGND, pins 13, 14, 23, and 24). 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 TPA3124D2.
•
Output filter—The reconstruction filter (L1, L2, C9, and C16) should be placed as close to the output terminals
as possible for the best EMI performance. The capacitors should be grounded to power ground.
•
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 are described in the mechanical section at the
back of the data sheet. See TI Technical Briefs
and
for more information about using the
thermal pad. For recommended PCB footprints, see figures at the end of this data sheet.
For an example layout, see the TPA3124D2 Evaluation Module (TPA3124D2EVM) User Manual, (
Both the EVM user manual and the thermal pad application note are available on the TI Web site at
.
18
Copyright © 2008, Texas Instruments Incorporated
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