TDA8932B_15 Datasheet, PDF (22/48 Pages) NXP Semiconductors – Class-D audio amplifier

NXP Semiconductors
TDA8932B
Class-D audio amplifier
14. Application information
14.1 Output power estimation
The output power P_o at THD+N = 0.5 %, just before clipping, for the SE and BTL
configuration can be estimated using Equation 2 and Equation 3.
SE configuration:
P_o(0.5%) = ---^----^R--------^L--------⁺----------^R-------^{D--------S-----o}-----^n-R-------^+-L---------^{R--------s------+----------R--------E------S-----}₈^R----^--_×---^×--_R--⁽--_L-¹----^–-----^t--^w---⁽--^m----ⁱ-ⁿ---⁾---^×------^f--^o---^s--^c--⁾----^×----^V-----^P------²
(2)
BTL configuration:
P_o(0.5%) = ---^----^R--------^L--------⁺---------^{2----------×---------(}----^R-^{R------L--D-------S}-----^{o------n-------+}----------^R--------^s-----⁾-₂^-----_××----_R-⁽--¹-_L----^–----^t--^w----⁽-^m----ⁱ--ⁿ--⁾---^×------^f---^o--^s--^c---⁾---^×-----^V----^P------²
(3)
Where:
V_P = supply voltage V_DDP1 − V_SSP1 (V) or V_DDP2 − V_SSP2 (V)
R_L = load impedance (Ω)
R_DSon = on-resistance power switch (Ω)
R_s = series resistance output inductor (Ω)
R_ESR = equivalent series resistance SE capacitor (Ω)
t_w(min) = minimum pulse width (s); 80 ns typical
f_osc = oscillator frequency (Hz); 320 kHz typical with Rosc = 39 kΩ
The output power P_o at THD+N = 10 % can be estimated by:
P_o(10%) = 1.25 × P_o(0.5%)
(4)
Figure 8 and Figure 9 show the estimated output power at THD+N = 0.5 % and
THD+N = 10 % as a function of the supply voltage for SE and BTL configurations at
different load impedances. The output power is calculated with: R_DSon = 0.15 Ω (at
T_j = 25 °C), R_s = 0.05 Ω, R_ESR = 0.05 Ω and I_O(ocp) = 4 A (minimum).
TDA8932B_4
Product data sheet
Rev. 04 — 18 December 2008
© NXP B.V. 2008. All rights reserved.
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