LA4183Description of External Parts C1 (C2) Feedback capacitor The low-range cut-off frequency is determined by the following formula: fL = 1 / (2 π C1vRf), fL: Low-range cut-off frequency Rf: Feedback resistor (50 Ω embedded + Rf externally connected) The frequency, however, affects the starting time in conjuction with decoupling capacitors. Therefore, it is necessary to determine it after a full review of the required low-frequency range and other similar conditions. C3 (C4) Bootstrap capacitor The output at low frequencies depends on this capacitor. If the capacity is decreased, the output at low frequencies goes lower. 47 µF min. is required. C5 (C6) Oscillation preventing capacitor Use polyester film capacitor which is good in temperature characteristic and frequency characteristic. Aluminum electrolytic capacitor or ceramic capacitor causes oscillation at low temperatures. C7 (C8) Output capacitor The low-range cut-off frequency is determined by the following formula. fL = 1 / (2π C7vRL), fL: Low-range cut-off frequency RL:Load resistance When using bridge-connected, double the capacitance to obtain equivalent low-range frequency characteristics to those in a 2-channel application. C9 Decoupling capacitor Used for the ripple filter. Since the rejection effect is saturated at a certain capacity, it is meaningless to increase the capacity more than needed. This capacitor, being also used for the time constant of the muting circuit, affects the starting time. C10 Power source capacitor Application Circuits 1. Voltage gain adjustment . Stereo The voltage gain depends on built-in-resistors R1 (R2), R3 (R4) as follows: R3 (R4) VG = 20 log [dB] R1 (R2) If the IC is used at a voltage gain less than this, the following equation with Rf added applies. R3 (R4) VG = 20 log [dB] R1 (R2) + Rf where R1 (R2) = 50 Ω typ., R3 (R4) = 10 kΩ typ. Bridge The following shows the bridge amplifier configuration, where ch1 operates as a non-inverting amplifier and ch2 as an inverting amplifier. No.887-4/12