TDA8920C Datasheet, PDF (17/40 Pages) NXP Semiconductors – 2 X110 W class-D power amplifier

NXP Semiconductors
TDA8920C
2 × 110 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 both channels
must be connected in 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 start-up. 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 Output power estimation
13.3.1 SE
Maximum output power:
P _{o ( 0.5 % )}
=
----^R--------^L---------^{+----------R--------D-------S}-----^{Ro------n--L----(----h-----s}-----^{)------+----------R--------s----L-----×}-----^V----^P-----^×-----⁽--¹-----^–----^t--^m----ⁱ--ⁿ----^×----⁰---^.--⁵----^f---^o---^s--^c---⁾----²-
2R_L
(1)
Maximum output current internally limited to 9.2 A:
I_{o( peak)} = ^V-----^P_R----_L^×----₊-⁽---¹-_R---^–-_D----^t_S--^m-_o--ⁱ-_n-ⁿ--₍-_h-^×--_s--₎-⁰---₊^.-⁵----_R-^f--_so---_Ls--^c---⁾
(2)
Where:
• R_L: load impedance
• R_sL: series impedance of the filter coil
• R_DSon(hs): high-side R_DSon of power stage output DMOS (temperature dependent)
• f_osc: oscillator frequency
• t_min: minimum pulse width (typical 150 ns, temperature dependent)
• V_P: single-sided supply voltage or 0.5 × (V_DD + |V_SS|)
• P_{o(0.5 %)}: output power at the onset of clipping
Remark: Note that I_o(peak) should be below 9.2 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 voltage drop over the coil.
TDA8920C_1
Preliminary data sheet
Rev. 01 — 29 September 2008
© NXP B.V. 2008. All rights reserved.
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