Ordering number : EN *5714 Monolithic Linear IC LA4906 17-W, 2-Channel BTL AF High-Efficiency Power Amplifier for Car Audio Systems Preliminary Overview The LA4906 is a BTL two-channel power amplifier for use in car audio systems. It uses a signal-following switching technique in the power supply for the amplifier output stage and a newly-developed nonlinear amplifier that features nonlinear characteristics in the signal system. These features hold increases in the number of external components to a minimum, and reduce power dissipation (and thus heat generation) in the practical operating region to about 1/2 that of earlier class B amplifier ICs. This can contribute significantly to miniaturization and weight reduction in the heat sink and to reduction of the heat generated within the end product case. • Uses a single-voltage power supply from 8 to 18 V. • Provides a full range of built-in protection circuits, including shorting of output pin to VCC, shorting of output pin to ground, overvoltage, and thermal shutdown protection. • Built-in standby switch • Clipping detection function Package Dimensions unit: mm 3160-SIP23HZ [LA4906] Features • Power dissipation reduced by 50% (for music at average power levels, as compared to earlier Sanyo products) • The number of required signal-following switching circuits has been reduced to just one circuit for two channels, reducing the number of external components. • The output is a pure analog signal; no switching noise whatsoever appears on the output lines. SANYO: SIP23HZ Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Maximum supply voltage Symbol VCC max1 Conditions Ratings With no signal, t = 1 minute VCC max2 Maximum output current IO Peak Per channel Allowable power dissipation Pd max With an arbitrarily large heat sink Unit 18 V 16 V 4.5 A 37.5 W Operating temperature Topr –35 to +85 °C Storage temperature Tstg –40 to +150 °C Notes: 1. Set VCC and RL to be in the range where Pd max does not exceed 37.5 W. 2. The overvoltage protection circuit operates at VCC = 26 V or higher. SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN 73097HA(OT) No. 5714-1/10 LA4906 Operating Conditions at Ta = 25°C Parameter Recommended supply voltage Allowable operating voltage range Recommended load resistance Recommended load resistance range Symbol Conditions Ratings VCC VCC op V 8 to 16 V 4 Ω 2 to 4 Ω RL RL op Unit 13.2 Note: Set VCC and RL to be in the range where Pd max does not exceed 37.5 W. Operating Characteristics at Ta = 25°C, VCC = 13.2 V, RL = 4 Ω, f = 1 kHz, RG = 600 Ω, in the recommended circuit Parameter Quiescent current drain Symbol ICC0 Standby current Ist Voltage gain VG Total harmonic distortion Output power Conditions RL = ∞, VIN = 0 Ratings min typ 80 VO = 0 dBm 28 THD PO = 1 W, LPF = 30 kHz PO1 THD = 10 %, RL = 4 Ω 14 max Unit 110 150 mA 0 10 µA 30 32 dB 0.07 0.2 17 % W PO2 THD = 10 %, RL = 2 Ω Output noise voltage VNO Rg = 0, BPF = 20 Hz to 20 kHz Ripple rejection ratio SVRR Rg = 0, VCCR = 0 dBm, BPF = 20 Hz to 20 kHz 60 75 dB Channel separation CH sep Rg = 10 kΩ, VO = 0 dBm, BPF = 20 Hz to 20 kHz 45 60 dB 21 30 Input resistance 25 Ri Output offset voltage VN offset Rg = 0 –200 Standby on voltage VSTH AMP = on, applied through a 10 kΩ resistor Clipping detect off current IDOFF THD = 1 % Clipping detect on current IDON THD = 10 % Heat sink thermal resistance, θf – °C/W Allowable power dissipation, Pd max – W 3 100 With an arbitrarily large heat sink Ambient temperature, Ta – °C 0.10 W 0.3 mVrms 39 kΩ +200 mV VCC V 1 10 µA 150 200 µA Al heat sink, t = 1.5 mm Tightening torque: 39 N·cm With silicone grease applied. Heat sink area, Sf – cm2 No. 5714-2/10 LA4906 Technologies for Increased Efficiency Used in the LA4906 • Signal-following switching technique The LA4906 uses a switching regulator for the power supply for the amplifier output stage. The LA4906 significantly reduces power dissipation by having the switching regulator output voltage follow the signal. Also, the LA4906 restricts the number of switching regulators required to just one circuit even though it implements a BTL 2-channel amplifier by using the switching regulator in combination with the nonlinear amplifier described below. (See Figure 1.) Regulator output Nonlinear amplifier Amplifier output stage Figure 1 Overview Block Diagram • Nonlinear amplifier The LA4906 adopts a nonlinear amplifier, which has the nonlinear characteristics shown in Figure 2, in the signal system. The LA4906 dispenses with the lower side switching regulator by using a low 2 V as the midpoint voltage instead of the 1/2 VCC used in normal amplifiers. This nonlinear amplifier is basically formed from a differential amplifier that has a symmetrical negative feedback circuit. Although the BTL output stage positive and reverse phase output waveforms have a half-wave waveform that, when referenced to ground, is expanded and compressed as shown in Figure 3, the combined output waveform at the load terminals is identical to that of earlier products. Figure 2 Nonlinear Amplifier Input/Output Characteristics Regulator output (point C) Loss in the output transistor Regulator output (point C) Reverse phase output (point B) Center point Ground Power dissipation, Pd – W Positive phase output (point A) Center point Ground RL = 4 Ω f = 1 kHz Rg = 600 Ω With both channels driven. Calculated at Pd = VCC × ICC – 2 PO Earlier SANYO products (class B amplifiers) Waveform between the outputs (Between A and B) High-efficiency LA4906 Output power, PO – W Figure 4 Figure 3 Output Waveforms No. 5714-3/10 LA4906 Equivalent Circuit Block Diagram Standby switch Standby switch Switching regulator block * Ripple filter TR1 Switching transistor 2SD1668, class S Switch driver (Tokin Co. Ltd.) * D1 SB40-05J Flywheel diode (OS capacitor) Amplifier output stage Input amplifier Nonlinear amplifier/output stage 4 to 2 Ω Beep amplifier Power supply/ground shorting protection circuit Overvoltage/thermal protection circuit * = Polyester film capacitors Input amplifier 4 to 2 Ω Nonlinear amplifier/output stage Muting circuit used at power on Popping noise prevention circuit Pin Voltages (At VCC = 13.2 V, with 5 V applied to STBY through a 10 kΩ resistor, using a digital voltmeter) Pin No. 1 2 3 4 5 6 7 8 Pin IN2 Pre - GND IN1 BEEP PWR - GND 1 –OUT1 +OUT1 C Pin voltage (V) 1.36 0 1.36 1.36 0 2.03 2.03 13.0 Pin No. 9 10 11 12 13 14 15 16 Pin C VCC VCC (SW) SW OUT1 SW OUT2 SW E SE B SW - GND 3.92 13.2 13.2 3.70 3.70 3.73 4.0 0 Pin voltage (V) Pin No. Pin Pin voltage (V) 17 18 19 20 21 22 23 +OUT2 –OUT2 PWR - GND2 D. C STAND-BY DDL OUT ON-TIME 2.03 2.03 0 12.1 3.21 0 2.81 No. 5714-4/10 LA4906 Sample Printed Circuit Board 1. External component descriptions C1 and C2 · Input capacitors. A value of 2.2 µ F is recommended for these capacitors. Note that the low-frequency area characteristics can be adjusted by changing fL, which is determined by the values of C1 and C2. However, due to impulse (pop) noise considerations, the value of C1 and C2 should not exceed 3.3 µF when C4 is 22 µF. C3 · Beep amplifier input capacitor. A value the same as that of C1 and C2 is used. If the beep function is not used, connect the beep input to PRE-GND through C3. C4 · Set the amplifier turn-on time. A value of 22 µF is recommended. (This will result in a turn-on time of about 0.7 second.) The on time is proportional to the value of this capacitor, and any value may be used. However, due to impulse (pop) noise considerations, a value of 22 µF or larger should be used. C5, C6, C7, and C8 · Oscillation prevention capacitors. Polyester film (Mylar) capacitors with good temperature characteristics must be used. (These are used together with R1, R2, R3, and R4.) We recommend values of 0.1 µF or higher for these capacitors since the stability will differ somewhat depending on the printed circuit board layout actually used. C9 · Decoupling capacitor (ripple filter) C10 · Power-supply capacitor C11 · Oscillation prevention capacitor for the switching regulator. A value of 1500 pF is recommended. C12 · Switching regulator output smoothing capacitor. The LA4906 adopts a self-excited switching regulator technique. The value of this capacitor must be optimized, since it influences both the self-excitation stability and the regulator efficiency. We recommend using a 2.2-µF 25-V OS (Organic Semiconductor) capacitor with a low series resistance and good temperature characteristics. Note that for the same reason a 2.2-Ω 1/2-W resistor should be used for the associated resistor R6. R5 · Standby switch current limiter resistor. A value of 10 kΩ is recommended. (When the voltage applied to the standby switch is in the range 3 to 13.2 V.) Note that this resistor cannot be removed from this circuit. No. 5714-5/10 LA4906 See the “Standby Function” section elsewhere in this document. TR1 · External switching transistor. The 2SD1668 (rank S) is recommended. If the application supports a load resistance RL of 4 Ω, a 2SD1667 (rank S) may be used. A heat sink must be provided for this transistor, as well as for the IC itself. D1 · Flywheel diode used to absorb energy from the coil. The SB40-05J, which is a Schottky barrier diode with a low VF, is recommended. If the application supports a load resistance RL of 4 Ω, an SB10-05A2 may be used. A heat sink must be provided for this diode, as well as for the IC itself. L1 · The Tokin Co., Ltd.-made HP-022Z [180 µH] (or the HP-011Z [200 µH] for 4-Ω applications) is recommended. 2. IC internal characteristics and other notes Switching regulator · The LA4906 includes a signal-following self-excited switching regulator to reduce power dissipation. The selfexcitation frequency with no input signal is about 100 kHz. · To avoid spurious signal interference within the end product case, it is desirable to separate the tuner block from the amplifier block by as far as possible. When designing the printed circuit board pattern, make the lines associated with the switching regulator external components as short and as wide as possible. · To prevent degradation of the LA4906 characteristics, separate the switching regulator external components from the IC inputs (the input block pattern, the input capacitors, and the beep amplifier capacitor) by at least 1.5 cm. Standby function Pin 21 IC Internal Equivalent Circuit 500 µA or less · Pin 21 is the standby switching pin. The amplifier is turned on by applying a voltage of over 3 V to pin 21 through an external resistor (R1). · If the standby switch applied voltage will exceed 13.2 V, then the current flowing into pin 5 must be held to under 500 µA. Use the following formula to determine the value of R1 that meets this condition. R1 = applied voltage – 1.4 V – 10 kΩ 500 µA About 1.4 V (2VBE) Applied standby voltage BEEP pin (pin 4) · If the BEEP pin is used, use the smallest value of R102 (see figure) possible (but note that this value must be under 100 Ω) to prevent degradation of the IC's output noise voltage (VNO) characteristics. Protection circuits · The LA4906 includes an on-chip thermal protection circuit to prevent destruction of or damage to the IC if abnormal heating occurs. If, due to an inadequate heat sink or other reason, the IC junction temperature (Tj) reaches or exceeds 160°C, the output is gradually attenuated by the operation of the thermal protection circuit. · The overvoltage protection circuit operates if the VCC voltage exceeds 20 V. · While the LA4906 includes a power supply/ground short protection circuit, it does not include a load shorting protection circuit. The idea behind this design is that the thermal shutdown protection circuit will protect the IC itself if the load is shorted. However, since a load short will also cause temperature increases in the external transistor and coil, care is required in handling this case. Beep signal Other notes · Pin 22 is not connected electrically to any other points within the package. No. 5714-6/10 Output power, PO – W Overvoltage protection circuit operation Output pin voltage, VN – V Quiescent current, ICCO – mA LA4906 Both channels operating Supply voltage, VCC –V ed ce ex Response – dB Total harmonic distortion, THD – % Both channels operating Output power, PO – W Output power, PO – W Both channels operating ak Supply voltage, VCC –V Total harmonic distortion, THD – % Total harmonic distortion, THD – % Supply voltage, VCC –V Both channels operating pe Both channels operating IO Output power, PO – W ed ce ex ak pe Both channels operating IO Output power, PO – W ed ed Input level, VIN – mV rms Input frequency, f – Hz Input frequency, f – Hz No. 5714-7/10 Channel separation, CHsep – dB Input frequency, f – Hz Ripple rejection ratio, SVRR – dB Using a 1-µF power-supply capacitor Supply voltage, VCC –V Ripple rejection ratio, SVRR – dB Power supply ripple current voltage, VCCR – Vrms Output power, PO – W f Both channels operating el Both channels operating its Power dissipation, Pd – W Current drain, ICC – A Ripple frequency, fR – Hz Using a 1-µF power-supply capacitor Calculate SVRR from the following formula:SVRR = 20 log (VO/VCCR) IC Using a 1-µF power-supply capacitor he Ripple rejection ratio, SVRR – dB Input resistance, Rg – Ω rt Output noise voltage, VNO – mV rms Input frequency, f – Hz fo Both channels operating Pd Output power, PO – W LA4906 Pd for the external transistor Output power, PO – W No. 5714-8/10 el its IC (Tokin Co., Ltd.) (OS capacitor) In the recommended circuit Quiescent current, ICCO – mA Regulator oscillator frequency, fOSC – kHz Output power, PO – W Supply voltage, VCC – V Both channels operating Ambient temperature, Ta – °C With VST applied to the standby pin (pin 21) through a 10-kΩ resistor Ambient temperature, Ta – °C Total harmonic distortion, THD – % Output power, PO – W he rt fo Pd for the external transistor Pd for the external transistor Output power, PO – W Output pin voltage, VN – V f Both channels operating Pd Power dissipation, Pd – W or t he I C its elf Both channels operating Pd f Power dissipation, Pd – W LA4906 Both channels operating Ambient temperature, Ta – °C With VST applied to pin 21 through a 10-kΩ resistor) · The time until the amplifier turns on after VST is applied Applied standby pin voltage, VST – V No. 5714-9/10 LA4906 ■ No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or indirectly cause injury, death or property loss. ■ Anyone purchasing any products described or contained herein for an above-mentioned use shall: ➀ Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associated with such use: ➁ Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees jointly or severally. ■ Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties. This catalog provides information as of July, 1997. Specifications and information herein are subject to change without notice. No. 5714-10/10