NXP Semiconductors TDA8932B Product Data Sheet

NXP Semiconductors TDA8932B Product Data Sheet Manual pdf 22 page image

TDA8932B_3 © NXP B.V. 21 June 2007. All rights reserved.Product data sheet Rev. 03— 21 June 2007 22 of 48NXP Semiconductors TDA8932BClass-D audio amplifier14. Application information14.1 Output power estimationThe output power Po at THD+N = 0.5 %, just before clipping, for the SE and BTLconfiguration can be estimated using Equation 2 and Equation 3.SE configuration:(2)BTL configuration:(3)Where:VP = supply voltage VDDP1 − VSSP1 (V) or V DDP2 − VSSP2 (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)tw(min) = minimum pulse width (s); 80 ns typicalfosc = oscillator frequency (Hz); 320 kHz typical with Rosc = 39 kΩThe output power Po at THD+N = 10 % can be estimated by:(4)Figure 8 and Figure 9 show the estimated output power at THD+N = 0.5 % andTHD+N = 10 % as a function of the supply voltage for SE and BTL configurations atdifferent load impedances. The output power is calculated with: RDSon = 0.15 Ω (atTj = 25 °C), Rs = 0.05 Ω, RESR = 0.05 Ω and I O(ocp) = 4 A (minimum).P o 0.5%( )R LR L R DSon R s R ESR+ + +----------------------------------------------------------   1 t w min( )– f osc×( )× V P×28 R L×-------------------------------------------------------------------------------------------------------------------------------------------=P o 0.5%( )R LR L 2+ R DSon R s+( )×------------------------------------------------------   1 t w min( )– f osc×( )× V P×22 R L×--------------------------------------------------------------------------------------------------------------------------------------=P o 10%( ) 1.25 P o 0.5%( )×=