LA4905 查看數據表（PDF） - SANYO -> Panasonic

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LA4905

17-W, 2-Channel BTL AF High-Efficiency Power Amplifier for Car Stereo Systems

SANYO -> Panasonic 

Sample Printed Circuit Board Pattern

LA4905

1. External Component Functions

C1, C2

C3

C4

C5, C6,

C7, C8

C9

C10

C11

C12

R5

TR1

D1

L1

• Input capacitors; recommended value: 2.2 µF. Note that the low-frequency band can be adjusted by changing

the values of C1 and C2, since fL depends on their value, although the value must not exceed 3.3 µF (when

C4 is 22 µF) due to pop noise considerations.

• Beep amplifier input capacitor. Use the same value as that used for C1 and C2. Connect the beep amplifier to

PRE-GND through C3 if the beep function is not used.

• Amplifier power-on delay time setting capacitor; recommended value: 22 µF. At the recommended value, the

amplifier will turn on in about 0.7 second after power is applied. The delay time is proportional to the

capacitance and can be set to an arbitrary value. However, a value of 22 µF or larger should be used due to

pop noise considerations.

• Oscillation prevention capacitors. Use capacitors with excellent temperature characteristics such as polyester

film or Mylar capacitors. These capacitors function in conjunction with R1, R2, R3, and R4. We recommend

using capacitors of 0.1 µF or larger, since the stability varies somewhat depending on the printed circuit

board layout.

• Decoupling capacitor (ripple filter)

• Power-supply capacitor

• Switching regulator oscillation prevention capacitor; recommended value: 1500 pF.

• Switching regulator output smoothing capacitor. The LA4905 adopts a self-excitation switching regulator

scheme. Since this capacitor influences the stability of the self-excitation and the regulator efficiency, there is

an optimal value. We recommend the use of a 2.2-µF, 25-V OS capacitor with good temperature

characteristics. Note that a 2.2-Ω, 1/2-W resistor should be used for R5 for the same reason.

• Standby switch current limiting resistor; recommended value: 10 kΩ.

(When the voltage applied to the standby switch is between 3 and 13.2 V.) Note that this resistor cannot be

removed. See the section "Standby Function" elsewhere in this document.

• External switching transistor. We recommend using a 2SD1668 of rank S. A 2SD1667 of rank S may be used if

the application is designed to handle 4-Ω loads (RL). A heat sink must be provided along with that for the IC.

• Flywheel diode that takes up the coil energy. We recommend using an SB40-05J, which is a Schottky barrier

diode with a low VF.

An SB10-05A2 may be used if the application is designed to handle 4-Ω loads (RL). A joint heat sink is not

required.

• We recommend the use of the HP-022Z 180-µH coil manufactured by Tokin, Ltd. The 200-µH HP-011Z may

be used if the application is designed to handle 4-Ω loads (RL).

No. 5504-5/10

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