Overview
The LA4905 is a BTL 2-channel power amplifier IC for u in car audio systems. Increas in the number of external components are held to a minimum by adopting both a signal-following type switching scheme in the amplifier’s output stage power supply, and a newly-developed nonlinear amplifier that has nonlinear characteristics in the signal system. The power dissipation (thermal loss) in the actual operating range has been reduced to about 1/2 that of earlier class B amplifier ICs.This contributes significantly to miniaturization of the heat sink and to reduction of heating within the t.
Features
•Power dissipation reduced by 50% (When average music power is measured, and when compared to earlier Sanyo products.)
•The number of required signal follower circuits has been reduced to a single circuit for two channels, a
llowing the number of external components to be reduced.
•The output is a pure analog signal: no switching noi is output to the output lines.
•Operates on an 8 to 18-V single-voltage power supply.•Full complement of built-in protection circuits (shorting to the power supply, shorting to ground, overvoltage,and thermal protection)•Built-in standby switch
Package Dimensions
unit: mm 3160-SIP23HZ
Monolithic Linear IC
Ordering number : EN5504
SANYO: SIP23HZ
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
Conditions
Ratings
Unit 24184.5With an arbitrarily large heat sink
37.5–35 to +85°C –40 to +150黄金蛋的做法
°C
Specifications
Maximum Ratings at Ta = 25°C
2.The overvoltage protection circuit operates when VCC is 20 V or higher.
Parameter
Symbol Conditions
Ratings Unit Recommended supply voltage
V CC 13.2V Allowable operating supply voltage range V CC op 8 to 18
V Recommended load resistance R L 4ΩRecommended load resistance range林中小溪
七夕小报R L op
恋风恋歌
2 to 4
Ω
Operating Conditions at Ta = 25°C
Operating Characteristics at Ta = 25°C, V CC = 13.2 V, R L = 4 Ω, f = 1 kHz, Rg = 600 Ω, in the recommended circuit
Notes:Set VCC and RL in the range where Pd max does not exceed 37.5 W.
曼珠沙华Parameter
Symbol Conditions
min typ max Unit Quiescent current Icco R L = ∞, V IN = 0
80
110150mA Standby current Ist 010µA Voltage gain
VG V O = 0 dBm
38
4042dB Total harmonic distortion THD P O = 1W, LPF = 30 kHz 0.070.2
%Output power 1P O 1THD = 10%, R L = 4 Ω1417W P O 2THD = 10%, R L = 2 Ω
25W Output noi voltage V NO Rg = 0, BPF = 20 Hz to 20 kHz
0.150.3mVrms Ripple rejection ratio SVRR Rg = 0, V CCR = 0 dBm, BPF = 20 Hz to 20 kHz 6070dB Channel paration CHp Rg = 10 k Ω, V O = 0 dBm, BPF = 20 Hz to 20 kHz
4555dB Input resistance Ri 2130
39k ΩOutput offt voltage VN offt Rg = 0你的容颜
–300
+300mV Standby on voltage
V STH
AMP = on, applied through a 10 k Ωresistor 3V CC V
LA4905 High-Efficiency Technology
(1) Signal-following switching scheme
The LA4905 adopts a switching regulator scheme in the power supply applied to the amplifier output stage.
The LA4905 power dissipation is reduced significantly by having the output voltage of the switching regulator follow the input signal. Furthermore, in combination with the nonlinear amplifier scheme described below, the LA4905 design reduces the number of switching regulators to merely one circuit even though it is a BTL 2-channel amplifier. (See Figure 1.)
(2) Nonlinear amplifier
The LA4905 adopts a nonlinear amplifier that has the
nonlinear characteristics shown in Figure 2 in the amplifier signal system. This scheme does not u the center point voltage of 1/2 VCC ud in normal amplifiers, but instead us a voltage about 2 V lower.
This allows the design to dispen with the lower side switching regulator.
漫步时光
This nonlinear amplifier has a structure bad on a differential amplifier that has symmetric negative feedback circuits. Although the BTL output stage positive and negative pha output waveform is a half-wave waveform that is expanded and compresd as shown in Figure 3, the combined output waveform at the negative load terminal is identical to that output by earlier products.
Equivalent Circuit Block Diagram
白洞Pin No.12345678Pin IN2Pre-GND
IN1BEEP PWR-GND 1
–OUT1+OUT1C Pin voltage (V)
1.36
1.36
1.36
2.03
2.03
13.0
Pin No.910111213141516Pin C V CC V CC (SW)SW OUT 1SW OUT 2SW E SW B SW-GND
Pin voltage (V)
3.92
13.2
13.2
3.70
3.70
3.73
4.0
Pin No.
17181920212223Pin +OUT 2–OUT 2PWR-GND 2
D. C STAND-BY
N. C ON-TIME Pin voltage (V)
2.03
2.03
12.1
3.21
2.81
Pin Voltages V CC = 13.2 V, 5 V applied to STBY through a 10-k Ωresistor, using a digital voltmeter
Sample Printed Circuit Board Pattern
1. External Component Functions C1, C2
• 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 e
xceed 3.3 µF (when C4 is 22 µF) due to pop noi considerations.
C3• Beep amplifier input capacitor. U the same value as that ud for C1 and C2. Connect the beep amplifier to PRE-GND through C3 if the beep function is not ud.
C4
• Amplifier power-on delay time tting capacitor; recommended value: 22 µF. At the recommended value, the amplifier will turn on in about 0.7 cond after power is applied. The delay time is proportional to the capacitance and can be t to an arbitrary value. However, a value of 22 µF or larger should be ud due to pop noi considerations.
C5, C6,• Oscillation prevention capacitors. U capacitors with excellent temperature characteristics such as polyester film or Mylar capacitors. The 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.
C9• Decoupling capacitor (ripple filter)C10• Power-supply capacitor
C11• Switching regulator oscillation prevention capacitor; recommended value: 1500 pF.
C12
• Switching regulator output smoothing capacitor. The LA4905 adopts a lf-excitation switching regulator scheme. Since this capacitor influences the stability of the lf-excitation and the regulator efficiency, there is an optimal value. We recommend the u 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 ud for R5 for the same reason.R5
• Standby switch current limiting resistor; recommended value: 10 k Ω.
(When the voltage applied to the standby switch is between 3 and 13.2 V.) Note that this resistor cannot be removed. See the ction "Standby Function" elwhere in this document.
TR1• External switching transistor. We recommend using a 2SD1668 of rank S. A 2SD1667 of rank S may be ud if the application is designed to handle 4-Ωloads (R L ). A heat sink must be provided along with that for the IC.D1
• Flywheel diode that takes up the coil energy. We recommend using an SB40-05J, which is a Schottky barrier diode with a low V F .
An SB10-05A2 may be ud if the application is designed to handle 4-Ωloads (R L ). A joint heat sink is not required.
L1
• We recommend the u of the HP-022Z 180-µH coil manufactured by Tokin, Ltd. The 200-µH HP-011Z may be ud if the application is designed to handle 4-Ωloads (R L ).
C7, C8
