NXP Semiconductors TDA8932B Product Data Sheet

NXP Semiconductors TDA8932B Product Data Sheet Manual pdf 24 page image

TDA8932B_3 © NXP B.V. 21 June 2007. All rights reserved.Product data sheet Rev. 03— 21 June 2007 24 of 48NXP Semiconductors TDA8932BClass-D audio amplifier14.2 Output current limitingThe peak output current IO(max) is internally limited above a level of 4 A (minimum). Duringnormal operation the output current should not exceed this threshold level of 4 Aotherwise the output signal is distorted. The peak output current in SE or BTLconfigurations can be estimated using Equation 5 and Equation 6.SE configuration:(5)BTL configuration:(6)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)Example:A 4 Ω speaker in the BTL configuration can be used up to a supply voltage of 18 V withoutrunning into current limiting. Current limiting (clipping) will avoid audio holes but it causesa comparable distortion like voltage clipping.14.3 Speaker configuration and impedanceFor a flat frequency response (second-order Butterworth filter) it is necessary to changethe low-pass filter components Llc and Clc according to the speaker configuration andimpedance. Table 14 shows the practical required values.14.4 Single-ended capacitorThe SE capacitor forms a high-pass filter with the speaker impedance. So the frequencyresponse will roll-off with 20 dB per decade below f-3dB (3 dB cut-off frequency).I O max( )0.5 V P×R L R DSon R s R ESR+ + +---------------------------------------------------------- 4 A≤ ≤I O max( )V PR L 2+ R DSon R s+( )×------------------------------------------------------ 4 A≤ ≤Table 14. Filter component valuesConfiguration R L (Ω) Llc (μH) Clc (nF)SE 4 22 6806 33 4708 47 330BTL 4 10 15006 15 10008 22 680