TDA8933 Datasheet, PDF (24/47 Pages) NXP Semiconductors – Class-D audio amplifier

NXP Semiconductors
TDA8933
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
configurations 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----------×---------(}-----^RR-------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 resistance (Ω)
R_DSon = drain-source on-state resistance (Ω)
R_s = series resistance output inductor (Ω)
R_ESR = equivalent series resistance SE capacitance (Ω)
t_w(min) = minimum pulse width (s); 80 ns typical
f_osc = oscillator frequency (Hz); 320 kHz typical with R_osc = 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 7 and Figure 8 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 = 0.35 Ω (at
T_j = 25 °C), R_s = 0.05 Ω, R_ESR = 0.05 Ω and I_O(ocp) = 2 A (minimum).
TDA8933_1
Preliminary data sheet
Rev. 01 — 15 May 2007
© NXP B.V. 2007. All rights reserved.
24 of 47