TPA3128D2

> 1.4sec

mP

TPA312xD2

SDZ

MUTE

FAULTZ

SDZ

MUTE

FAULTZ

17

TPA3128D2, TPA3129D2

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SLOS941C – MAY 2016 – REVISED JANUARY 2018

Product Folder Links: TPA3128D2 TPA3129D2

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Copyright © 2016–2018, Texas Instruments Incorporated

Figure 28. MUTE Driven by Inverted FAULTZ

Figure 29. Timing Requirement for SDZ

7.3.11 Thermal Protection

Thermal protection on the TPA31xxD2 prevents damage to the device when the internal die temperature

exceeds 150°C. This trip point has a ±15°C tolerance from device to device. Once the die temperature exceeds

the thermal trip point, the device enters into the shutdown state and the outputs are disabled. This is a latched

fault.

Thermal protection faults are reported on the FAULTZ terminal as a low state.

If automatic recovery from the thermal protection latch is desired, connect the FAULTZ pin directly to the SDZ

pin. This allows the FAULTZ pin function to automatically drive the SDZ pin low which clears the thermal

protection latch.

7.3.12 Device Modulation Scheme

The TPA3128D2 and TPA3129D2 have the option of running in either BD modulation or low idle-loss mode.

7.3.12.1 BD-Modulation

This is a modulation scheme that allows operation without the classic LC reconstruction filter when the amp is

driving an inductive load with short speaker wires. Each output is switching from 0 volts to the supply voltage.

The OUTPx and OUTNx are in phase with each other with no input so that there is little or no current in the

speaker. The duty cycle of OUTPx is greater than 50% and OUTNx is less than 50% for positive output voltages.

The duty cycle of OUTPx is less than 50% and OUTNx is greater than 50% for negative output voltages. The

voltage across the load sits at 0V throughout most of the switching period, reducing the switching current, which

reduces any I2R losses in the load.