Datasheet LA4558 (Sanyo) - 3

LA4558 Sample Printed Circuit Pattern
(Cu-foiled side)
Sample Application Circuit :
Bridge Amplifier Use
Description of External Parts
C1 (C2) : Feedback capacitor. The low cutoff frequency is determined by the following formula. 1 fL : Low cutoff frequency fL= 2πC1Rf Rf : Feedback resistance Since this capacitor as well as decoupling capacitor affects the starting time, the capacitor value must be fixed with the necessary low frequency band fully considered. C3 (C4) : Bootstrap capacitor. The output at low frequencies depends on this capacitor. Decreasing the capacitor value lowers the output at low frequencies. A capacitor value of 47µF or more is required. C5 (C6) : Oscillation blocking capacitor. Use a polyester film capacitor that is good in high frequency response and temperature characteristic. The use of an electrolytic capacitor, ceramic capacitor may cause oscillation to occur at low temperatures. C7 (C8) : Output capacitor. The low cutoff frequency is determined by the following formula. 1 fL : Low cutoff frequency fL= 2πC7RL RL : Load resistance To make the low frequency response in the bridge amplifier mode identical with that in the stereo mode, the capacitor value must be doubled. C9 : Decoupling capacitor CD1. Used for the ripple filter. Since the rejection effect is saturated at a certain capaci- tor value, it is meaningless to increase the capacitor value more than needed. This capacitor, being also used for the time constant of the muting circuit, affects the starting time. C10 : Power source capacitor. C11 : Decoupling capacitor CD2. Used for the ripplie filter. Particularly effective for transient characteristic. No.2088–3/9