NXP Semiconductors TDA8932B Uživatelský manuál stáhnout pdf (Strana 22)

Product data sheet Rev. 03— 21 June 2007 22 of 48

NXP Semiconductors

TDA8932B

Class-D audio ampliﬁer

14. Application information

14.1 Output power estimation

The output power P

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:

(2)

BTL conﬁguration:

(3)

Where:

= supply voltage V

DDP1

− V

SSP1

(V) or V

DDP2

− V

SSP2

(V)

= load impedance (Ω)

DSon

= on-resistance power switch (Ω)

= series resistance output inductor (Ω)

ESR

= equivalent series resistance SE capacitor (Ω)

w(min)

= minimum pulse width (s); 80 ns typical

osc

= oscillator frequency (Hz); 320 kHz typical with Rosc = 39 kΩ

The output power P

at THD+N = 10 % can be estimated by:

(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

=25°C), R

= 0.05 Ω, R

ESR

= 0.05 Ω and I

O(ocp)

= 4 A (minimum).

o 0.5%()

DSon

ESR

+++

----------------------------------------------------------





wmin()

– f

osc

×()× V

-------------------------------------------------------------------------------------------------------------------------------------------

o 0.5%()

2+ R

DSon

+()×

------------------------------------------------------





wmin()

– f

osc

×()× V

--------------------------------------------------------------------------------------------------------------------------------------

o10%()

1.25 P

o 0.5%()

×=

1 2 ... 17 18 19 20 21 22 23 24 25 26 27 ... 47 48

TDA8932B 1

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