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TPA2026D2

www.ti.com

SLOS649B – MARCH 2010 – REVISED MAY 2016

Product Folder Links: TPA2026D2

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Copyright © 2010–2016, Texas Instruments Incorporated

Figure 42. Output Signal vs Input Signal State Diagram

9.3.2 Operation With DACS and CODECS

In using Class-D amplifiers with CODECs and DACs, sometimes there is an increase in the output noise floor

from the audio amplifier. This occurs when output frequencies of the CODEC/DAC mix with the Class-D

switching frequency and create sum or difference components in the audio band. The noise increase can be

solved by placing an RC low-pass filter between the CODEC/DAC and audio amplifier. The filter reduces high

frequencies that cause the problem and allows proper performance.

If driving the TPA2016D2 input with 4th-order or higher

ΔΣ DACs or CODECs, add an RC low-pass filter at each

of the audio inputs (IN+ and IN–) of the TPA2016D2 to ensure best performance. The recommended resistor

value is 100

Ω and the capacitor value of 47 nF.

9.3.3 Short-Circuit Auto-Recovery

When a short-circuit event happens, the TPA2026D2 goes to low duty cycle mode and tries to reactivate itself

every 110 µs. This auto-recovery continues until the short-circuit event stops. This feature can protect the device

without affecting the device's long-term reliability. FAULT bit (register 1, bit 3) still requires a write to clear.

9.3.4 Filter-Free Operation and Ferrite Bead Filters

A ferrite bead filter can often be used if the design is failing radiated emissions without an LC filter and the

frequency-sensitive circuit is greater than 1 MHz. This filter functions well for circuits that just have to pass FCC

and CE because FCC and CE only test radiated emissions greater than 30 MHz. When choosing a ferrite bead,

choose one with high impedance at high frequencies, and low impedance at low frequencies. In addition, select a

ferrite bead with adequate current rating to prevent distortion of the output signal.

Use an LC output filter if there are low frequency (< 1 MHz) EMI-sensitive circuits or there are long leads from

amplifier to speaker. Figure 43 shows typical ferrite bead and LC output filters.