Ordering number : ENA032 LA4902 Monolithic Linear IC Audio Output for TV application 0W BTL Monaural Power Amplifier IC Overview The LA4902 is a high-efficiency monaural BTL power amplifier. The LA4902 holds the number of external components to a minimum and reduces power consumption (thermal loss) in the operating range to one half that of earlier class B power amplifiers by using a signal following switching system for the power supply to the amplifier output stage and by including a nonlinear amplifier in the signal system. The use of a DIP-28H package obviates the need for a separate heat sink and can contribute to internal space savings in end products. Functions High-efficiency 0W monaural BTL power amplifier (VCC = 4V, RL = 8 ) Provided in a DIP-28H package (no heat sink is required) The number of required signal-following switching circuits has been held to a single circuit, thus reducing even further the number of external components required. The output is a fully analog signal, and no switching noise appears on the output lines. Built-in standby switch (amplifier block/headphone block) Built-in headphone amplifier : input/2 output (VG = 6dB, PO = 60mW) Built-in protection circuits (overvoltage and thermal protection circuits) Specifications Maximum Ratings at Ta = 25 C Parameter Symbol Conditions Ratings Unit Maximum supply voltage V CC max No signal 24 V Allowable power dissipation Pd max With a infinity large heat sink 5 W Thermal resistance j-c 3 C/W Maximum junction temperature Tj max 50 C Operating temperature Topr -25 to 75 C Storage temperature Tstg -40 to 50 C Any and all SANYO Semiconductor products described or contained herein do not have specifications that can handle applications that require extremely high levels of reliability, such as life-support systems, aircraft's control systems, or other applications whose failure can be reasonably expected to result in serious physical and/or material damage. Consult with your SANYO Semiconductor representative nearest you before using any SANYO Semiconductor products described or contained herein in such applications. SANYO Semiconductor assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all SANYO Semiconductor products described or contained herein. N506 MS PC B8-483 No.A032-/5
Operating Conditions at Ta = 25 C Parameter Symbol Conditions Ratings Unit Recommended supply voltage V CC 4 V Recommended load resistance R L 8 Operating supply voltage range V CC op The range where the package Pd is not exceeded 8 to 8 V Electrical Characteristics at Ta = 25 C Ratings Parameter Symbol Conditions Unit min typ max [Amplifier Block] V CC = 4V, R L = 8, f = khz, Rg = 600, See the specified board and circuit. Quiescent current I CCO Rg = 0 25 40 80 ma Standby current Ist 0 0 A Voltage gain VG V O = 0dBm 28 30 32 db Output power P O THD = 0% 8 0 W Total harmonic distortion THD P O = W, LPF = 30kHz 0. 0.4 % Output noise voltage V NO Rg = 0, DIN AUDIO 0. 0.3 mv Ripple rejection SVRR Rg = 0, fr = 00Hz, VR = 0dBm, DIN AUDIO 60 70 db Input resistance Ri 2 30 39 k Output offset voltage V N offset Rg = 0-200 200 mv Standby mode on voltage V ST With the amplifier in, and the voltage applied 3 V CC V through a 0k resistor [Headphone Block] V CC = 4V, R L = 32, f = khz, Rg = 600, See the specified board and circuit. Voltage gain VG V O = 0dBm 5 6 7 db Output power P O THD = 0% 50 60 mw Total harmonic distortion THD V O = 0dBm, LPF = 30kHz 0.025 0.05 % Ripple rejection SVRR Rg = 0, fr = 00Hz, VR = 0dBm, DIN AUDIO 75 85 db Output noise voltage V NO Rg = 0, DIN AUDIO 0.0 0.04 mv Package Dimensions unit : mm (typ) 347C 28 5 7 6 Pd max -- Ta R.7 20.0 4 26.75 5 4 With a infinity large heat sink, jc=3 C/W Mounted on the specified circuit board 3.5W 3 Independent IC 2.5W 2 2.W 5W.5W (.8).78 0.6.0 0 0 20 40 60 80 00 20 40 60 Ambient temperature, Ta C SANYO : DIP28H(500mil) No.A032-2/5
Block Diagram Headphone L R ch 00 F/0V HP OUT * 0.047 F 0 47 F/25V SW GND 2 3 Ripple filter V CC VG=6dB Voltage regulator Headphone standby switch Ripple filter 28 HP IN F/0V H/P Standby 27 0k 5V D.C 26 47 F/25V SW GND 4 Amplifier standby switch Switching regulator block 25 AMP Standby 0k 5V Switching transistor A ft=30 to 50MHz SW B 5 Switching drive H. L. S 24 Flywheel diode F/25V (OS capacitor) SW E 200 H SW OUT V CC (SW) 6 7 8 B A *H.L.S Higher Level signal Selector On time muting circuit Impulse noise prevention circuit 23 22 2 ON TIME 22 F/6.3V B 000 F/25V V CC 9 20 PRE GND 0 9 000pF * 0. F * 0. F OUT - OUT 2 3 Output amplifier A B Nonlinear amplifier Input amplifier IN BE EP Beep amplifier 8 7 F/6.3V 6 F/6.3V 4 Output amplifier 5 * Polyester film capacitor No.A032-3/5
High-efficiency technologies used in the LA4902. Signal following switching method The switching regulator technique is adopted in the LA4902's power supply system used for the amplifier's output stage. Power consumption is reduced significantly by having the switching regulator's output voltage follow the signal level. Furthermore, we were able to hold the number of switching regulator circuits required to a single circuit by use in combination with the nonlinear amplifier technique described below. (See figure.) Block Diagram Regulator output Nonlinear amplifier V IN Switching regulator C A B Amplifier's output stage V CC [Figure ] 2. Nonlinear amplifier technique The LA4902 adopts a nonlinear amplifier in the amplifier signal system that has the nonlinear characteristics shown in figure 2. This system eliminates the need for the switching regulator used for the low side signal by lowering the midpoint voltage from the /2 VCC used in normal amplifiers to about 2V. This nonlinear amplifier is formed based on a differential amplifier that has a symmetrical negative feedback circuit. Although the BTL output stage positive phase and reverse phase output waveforms have the compressed/expanded half-wave waveform shown in figure 3, the synthesized output waveform at the negative terminal is the same as that output by earlier products. Nonlinear Amplifier I/O Characteristics OUTPUT [Figure 2] INPUT Output Waveforms Regulator output Output transistor loss Positive phase output (A) Midpoint voltage GND Reverse phase output (B) Between outputs (A - B) [Figure 3] No.A032-4/5
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