TDA8922C Datasheet, PDF (17/40 Pages) NXP Semiconductors – 2 X 75 W class-D power amplifier

NXP Semiconductors
TDA8922C
2 × 75 W class-D power amplifier
13. Application information
13.1 Mono BTL application
When using the power amplifier in a mono BTL application, the inputs of the two channels
must be connected in anti-parallel and the phase of one of the inputs must be inverted;
(see Figure 7). In principle, the loudspeaker can be connected between the outputs of the
two single-ended demodulation filters.
13.2 Pin MODE
To ensure a pop noise-free start-up, an RC time-constant must be applied to pin MODE.
The bias-current setting of the VI converter input is directly related to the voltage on pin
MODE. In turn the bias-current setting of the VI converters is directly related to the DC
output offset voltage. A slow dV/dt on pin MODE results in a slow dV/dt for the DC output
offset voltage, ensuring a pop noise-free transition between Mute and Operating modes. A
time-constant of 500 ms is sufficient to guarantee pop noise-free start-up; see Figure 4,
Figure 5 and Figure 8 for more information.
13.3 Estimating the output power
13.3.1 Single-Ended (SE)
Maximum output power:
P _{o ( 0.5 % )}
=
----^R--------^L---------^{+----------R--------D-------S}-----^{o----R--n------L(----h-----s}-----^{)------+----------R--------s----(----L------)}---^×-----⁰---^.-⁵----⁽--^V-----^D----^D-----^–----^V----^S---^S---⁾----^×----⁽---¹----^–-----^t--^w---⁽--^m----ⁱ--ⁿ--⁾---^×-----⁰---^.--⁵----^f---^o--^s---^c--⁾-----²-
2R_L
(1)
Maximum output current is internally limited to 6 A:
I_{o( peak)} = ⁰----^.-⁵---⁽---^V----^D----^D----_R-^–---_L--^V---₊-^S---^S-_R--⁾-_D--^×--_S---⁽_o--¹-_n---₍-^–-_h--_s-^t--₎^w---₊-⁽--^m--_R--ⁱ--^ns--₍₎--_L-^×--₎---⁰---^.--⁵----^f---^o---^s--^c--⁾
(2)
Where:
• P_{o(0.5 %)}: output power at the onset of clipping
• R_L: load impedance
• R_DSon(hs): high-side R_DSon of power stage output DMOS (temperature dependent)
• R_s(L): series impedance of the filter coil
• t_w(min): minimum pulse width (typical 100 ns, temperature dependent)
• f_osc: oscillator frequency
Remark: Note that I_o(peak) should be less than 6 A (Section 8.3.2). I_o(peak) is the sum of the
current through the load and the ripple current. The value of the ripple current is
dependent on the coil inductance and the voltage drop across the coil.
TDA8922C_1
Product data sheet
Rev. 01 — 7 September 2009
© NXP B.V. 2009. All rights reserved.
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