TECHNICAL NOTE Speaker / Headphone Amplifier Series 2W + 2W Stereo Speaker / Headphone Amplifier BH7881EFV ●Description The BH7881EFV is a low voltage, low noise, high output speaker/headphone amplifier IC, in which a BiCMOS process is used. An on-chip speaker amplifier circuit that is capable of 2W+2W output can be used as a headphone amplifier by switching the operating mode. This makes it possible to configure an audio system using few external devices. With a built-in, low saturation regulator with programmable output voltage and output current, clear tone quality is obtained even when directly connected to a digital power supply. A peripheral analog circuit can also be regulator driven. Furthermore, the BH7881EFV provides speaker output and VREG output short-circuit detection functions, a thermal shutdown function with hysteresis, and a speaker protection function. ●Features 1) Built-in low saturation type regulator (Digital power supply driver, voltage and current variable, short circuit detection) 2) Bass boost mode, gain switching functions 3) Speaker MUTE function (Headphone mode) 4) Built-in line amplifier output (gain adjustment, LPF setting) active/suspend function (TTL input control pin) 5) Hysteretic thermal shutdown function (Set for approximately 150°C /90°C) 6) IC protection function (SP pin VCC/GND short circuit detection) 7) Speaker protection function (Output voltage amplitude control) ●Applications Notebook computers, LCD TVs, etc. ●Absolute maximum ratings (Ta=25°C) Parameter Limits Unit Supply voltage +6.0 Ｖ Power dissipation 1100 mW Storage temperature -55～+125 °C Operating temperature -10～+70 °C *1 Reduced by 11 mW/C at 25C or higher, when mounting on a 70mmX70mmX1.6mm PCB board). *1 ●Operating range (Ta=25°C) Parameter Supply voltage Limit +3.3～+5.5 Unit V * This IC is not designed to be radiation-resistant. Oct. 2005 ●Electrical characteristics (Unless otherwise noted, VCC=3.3V,Ta=25°C,f=1kHz,R=4Ω,400Hz～30kHzBPF) Specifications Parameter Unit Condition Min. Typ. Max. Circuit current (ACTIVE) - 18 30 mA No signal Circuit current(SUSPEND) - 0 10 μA No signal Voltage gain1 8.5 11.0 13.5 dB SE,Vin=-18dBV Voltage gain 2 14.5 17.0 19.5 dB BTL,Vin=-18dBV - 0.04 1.0 % BTL,Vin=-18dBV 1.5 4.5 - dBV BTL,DSTN=1% Output noise level - -90 -80 dBV SE,DIN-Audio Cross talk - -85 -75 dBV SE,DIN-Audio Output level on mute - -110 -80 dBV BTL,Vin=-18dBV 3.0 5.5 8.0 dB SE,Vin=-18dBV,RL=32Ω - 0.02 1.0 % SE,Vin=-18dBV,RL=32Ω -1.6 1.4 - dBV SE,DSTN=1% ,RL=10kΩ ■1CHIP ■SP AMP Distortion Maximum output level ■HP AMP Voltage gain Distortion Maximum output level Output noise level - -95 -80 dBV SE,DIN-Audio ,RL=32Ω Cross talk - -90 -80 dBV SE,DIN-Audio ,RL=32Ω Output level on mute - -105 -80 dBV SE,Vin=-18dBV,RL=32Ω 1.40 1.65 1.90 V No signal 2.7 3.0 - V No signal - -80 - dBV VCC/3+0.8 - VCC V SP/HP® SUSPEND 0 - 0.8 V SP/HP® ACTIVE VCC/3+0.8 - VCC V SP/HP ON 0 - 0.8 V SP OFF(SP MUTE),HP ON ■BIAS Output voltage ■Regulator Output voltage PSRR VIN=0.28Vpp,1kHz ■CONTROL PIN ACTV/SPND CTRL 2PIN control pin SUSPEND mode ACTIVE mode SP/HP CTRL 12PIN control pin SP&HP mode HP(SP MUTE) mode BASSBOOST CTRL 11PIN control pin Bass-Boost mode VCC/3+0.8 - VCC V SP/HP gain UP Non-Boost mode 0 - 0.8 V SP/HP gain NORMAL 2/8 ●Block diagram Fig.1 ●Control pin descriptions 1．ACTIVE/SUSPEND：2PIN Control input Mode Function H SUSPEND Suspended state (Except REG) L ACTIVE Active state When suspended, the regulator (REG) is in an active state and the SP/HP/LINE amplifier is in a suspended state. Originally, signals from input resistance and feedback resistance leaked into the speaker output even when suspended, because of the series connection of an inverting amplifier. However, since the signals are cut off on their way in this IC, signal leaks do not occur in speaker output. (Signals due to feedback resistance are output in LINE amplifier output.) 2．POWER LEVEL：8PIN Control input Mode Function H Limiter H 3Vf peak limiter ON (Output approx. 1.25 W) OPEN Limiter L 2Vf peak limiter ON(Output approx .0.70W) L Limiter OFF limiter OFF *VCC=5V,RL=4ohm,VIN=-8dBV Since a limiter uses diode characteristics, it has temperature characteristics. On the high temperature side, amplitude tends to decrease, which is a characteristic that protects the IC. Since setting in speaker mode is assumed, it is ineffective (limiter OFF) in headphone mode. Moreover, precautions must be taken when input is so great, that output becomes a square wave, since this could cause local oscillation. 3．BASSBOOST ON/OFF：11PIN Control input Mode Function H ON BASSBOOST:ON L OFF BASSBOOST:OFF The capacitor that constitutes BASSBOOST is eliminated, and also functions as a gain switch. 4．SP/HP：12PIN Control input Mode Function H SP+HP SP:ON, HP:ON L HP SP:OFF,HP:ON By using the headphone mode in a speaker MUTE mode, it is possible to completely cut off the pop noise when switching when VCC ON or OFF, or to ACTV or SPND. For control sequence and other information, see the following pages. ＊Not all control pins have pull up or pull internal resistors. Therefore add pull up or pull down resistors, accordingly (PIN8 is an exception.) 3/8 ●Description of operations (1 of 3) 1. 2. 3. LINE Amplifier 1) The voltage gain of the LINE amplifier is calculated by the following equations: GAIN = 20×LOG(68k/R4 +1k)) [dB] GAIN = 20×LOG(68k/R9 +1k)) [dB] R4 and R9 are resistances connected to PIN4 and PIN9 2) In order to make it operable with mixing input, the LINE amplifier can be realized by connecting multiple resistors to PIN4 and PIN9. Since the input pin is also the feedback of an inverting differential amplifier, each individual signal is simply added. 3) To configure LPF and remove unnecessary frequency components, the LINE amplifier can be realized by connecting capacitors between PIN3 and PIN4, and between PIN9 and PIN10. The LPF cut-off frequency at that time is calculated by the following equation: fc = 1/(2×π×C×68k) [Hz] SP Amplifier (HP Amplifier) 1) The voltage gain of the SP amplifier for Non-Boost is about 12 [dB] (SE: Single end). 2) The voltage gain of the SP amplifier for Bass-Boost is calculated by the following equations: Where R22-23 is the resistance connected between PIN22 and PIN23. GAIN = 20×LOG((40k+R22-23)/10k) [dB] GAIN = 20×LOG((40k+R14-15)/10k) [dB] Where R14-15 is the resistance connected between PIN14 and PIN15. 3) The cut-off frequency for Bass-Boost is calculated by the following equations: fc = 1/(2×π×C22-23×R22-23) [Hz] Where RC22-23 is connected between PIN22 and PIN23. fc = 1/(2×π×C14-15×R14-15) [Hz] Where RC14-15 is connected between PIN14 and PIN15. 4) Apply power to RCHVCC (PIN13), for MONO only. Regulator 1) The REG output voltage is calculated by the following equation, and numeric values are shown below: V = 1.15 [V]×(1+R(VLEV)/R(VREF)) [V] REG setting voltage 3.0 3.3 3.6 4.0 Supply voltage(VCC) 3.3 3.6 4.0 5.0 R(VLEV) 30k 30k 30k 30k R(VREF) 18k 16k 14k 12k Use 1% resistors to eliminate errors in actual output voltages. 4.6 5.0 30k 10k V V Ω Ω 2) The REG maximum output current is determined by the external Tr capability (hFE) of the IC. If more current is necessary, select one ICMAX with large hFE. Drive output current to the base is about 5 mA. 3) When using the regulator, connect REG output to PIN6. The LINE amplifier, BIAS, and other sections essential to tone quality, are driven by the REG voltage. Clear sound output is obtained even if a digital power supply is the VCC. 4) When using the regulator for an application, other than this IC, and driving the IC by VCC only, apply VCC at PIN6. 5) When not using the regulator, it is set to OFF mode by connecting PIN 19 to OPEN and PIN18 to OPEN. Apply VCC at PIN6. 6) Do not set a VCC applied voltage that is smaller than the set voltage of the regulator. Since the REG output transistor operates in a saturation region, an abnormal circuit current occurs. 7) For the REG output transistor, Rohm transistors 2SA1900 and 2SA933 are recommended. 4/8 4. 5. Short circuit detection 1) Overview of SP amplifier VCC/GND short circuit detection If the output pin of the SP amplifier is short circuited to VCC or GND, the detection function operates to suspend the output stage of the SP amplifier. If the SP output pin is short circuited to REG output, the detection function does not operate. It is configured so that it resets automatically if the short circuit is canceled. Moreover, although a short circuit is detected from the DC voltage of the output pin, and there is a short delay distinguishing it from a maximum output amplitude, malfunction may occur due to factors such as power supply voltage and load. In this case, connect “PIN7” to GND. The short circuit function is set to the OFF mode. 2) SP amplifier VCC/GND short circuit detection cautions When the output pin of the SP amplifier is short circuited with VCC or GND, an excessive current flows in the IC and stress is applied to the chip. Accordingly, if it is shorted a number of times, the IC gradually deteriorates and is finally destroyed. The short circuit detection function does not guarantee operation after numerous shorts. 3) Regulator short circuit detection If the output pin of the regulator is short circuited to GND, the detection function operates to suspend the output stage of the regulator. If the output pin of the regulator is short circuited to VCC, an abnormal current does not occur in any circuit. After the short circuit, the regulator resets automatically, due to the pull-up resistance (for example, 2.2 kΩ) connected to PIN1, as shown in the full option example of the sample application circuit. (Example: 3.9 kΩ is the resistance load for lowering the output impedance of the regulator when it is no load.) Pop noise 1) The following table shows the sequence for eliminating the pop noise that occurs from turning the power supply ON or OFF, or turning control pins ON or OFF. 2) Order VCC ACT/SPND SP/HP 1 2 3 4 5 6 7 8 OFF ON ON ON ON ON ON OFF SUSPEND SUSPEND ACTIVE ACTIVE ACTIVE ACTIVE SUSPEND SUSPEND HP HP HP SP+HP SP+HP HP HP HP Power Supply ON Turning on in the suspend SP MUTE～countermeasure MUTE cancellation～operation Operation SP MUTE～counter measure Turning off in the suspend Power Supply OFF In speaker MUTE state, pop noise does not occur even when starting or changing modes. It is recommended to use speaker MUTE (headphone) mode during conditions where pop noise can occur. 3) Any changes of the components values in the sample application circuit can effect the pop noise cut-off function. 6. Bypass and bias capacitor 1) Although this IC is designed so that bypass capacitors are not needed, when bypass capacitors are in fact necessary, place them close to the VCC~GND pins. 2) 7. Similarly, place a bias capacitor close to the GND pin. Capacitive load drive 1) Do not connect a capacitive load to the SP amplifier, HP amplifier, or IC pin. There is a possibility of oscillation. 2) Adding RC to the HP amplifier output, as in the sample application circuit, makes the output noise, voltage, and distortion sensitive to oscillation. 5/8 8. Pop noise at start/end when switching ACTV/SPND Pop noise can be suppressed by mode transition due to software as in “Pop noise” above, or by hardware as shown below. This is realized (in SP mode) by forcibly setting HP mode temporarily, using the CR differential circuit. 9. Power package 1) In order to expand the power dissipation of the package, make the GND pattern, directly below the IC, as wide as possible and solder the GND pattern to the back of the IC. 2) Power dissipation of the package varies greatly depending on factors such as the number of layers, area, film thickness, and material quality of the board used. 10. Other Beween voltages of VCC=1.4 ～ 1.6 V, momentary oscillation sometimes is observed at the SPOUT pin. Nevertheless, this occurrence is not reproduced on a momentary rise or fall of VCC. When slowly raising VCC pay attention to transient voltage. In order to avoid such occurrences, a sample circuit is illustrated below: ●Application circuit (1 of 2) Fig.4 Minimum external components example 6/8 ●Application circuit (2 of 2) ●Operation Notes 1. 2. 3. 4. 5. 6. 7. Numbers and data in entries are representative design values and are not guaranteed values of the items. Although ROHM is confident that the example application circuit reflects the best possible recommendations, be sure to verify circuit characteristics for your particular application. Modification of constants for other externally connected circuits may cause variations in both static and transient characteristics for external components as well as this Rohm IC. Allow for sufficient margins when determining circuit constants. Absolute maximum ratings Use of the IC in excess of absolute maximum ratings, such as the applied voltage or operating temperature range (Topr), may result in IC damage. Assumptions should not be made regarding the state of the IC (short mode or open mode) when such damage is suffered. A physical safety measure, such as a fuse, should be implemented when using the IC at times where the absolute maximum ratings may be exceeded. GND potential Ensure a minimum GND pin potential in all operating conditions. Make sure that no pins are at a voltage below the GND at any time, regardless of whether it is a transient signal or not. Thermal design Perform thermal design, in which there are adequate margins, by taking into account the permissible dissipation (Pd) in actual states of use. Short circuit between terminals and erroneous mounting Pay attention to the assembly direction of the ICs. Wrong mounting direction or shorts between terminals, GND, or other components on the circuits, can damage the IC. Operation in strong electromagnetic field Using the ICs in a strong electromagnetic field can cause operation malfunction. 7/8 ●Selection of order type B H 7 8 8 1 E V F E 2 Tape and Reel information Part No. BH7881EFV HTSSOP-B24 <Tape and Reel information> <Dimension> 7.8 ± 0.1 1 12 1234 1234 1234 1234 1234 1234 +0.05 −0.04 E2 (Correct direction: 1pin of product should be at the upper left when you hold reel on the left hand, and you pull out the tape on the right hand) 1234 0.2 2000pcs +0.05 0.17 −0.03 0.08 S 0.65 Quantity 1234 1.0Max. 0.85 ± 0.05 0.08 ± 0.05 0.325 Embossed carrier tape Direction of feed 0.53 ± 0.15 1 ± 0.2 13 7.6 ± 0.2 5.6 ± 0.1 24 4 +6 −4 Tape 0.08 M Reel （Unit:mm) 1pin Direction of feed ※Orders are available in complete units only. The contents described herein are correct as of October, 2005 The contents described herein are subject to change without notice. For updates of the latest information, please contact and confirm with ROHM CO.,LTD. Any part of this application note must not be duplicated or copied without our permission. Application circuit diagrams and circuit constants contained herein are shown as examples of standard use and operation. Please pay careful attention to the peripheral conditions when designing circuits and deciding upon circuit constants in the set. Any data, including, but not limited to application circuit diagrams and information, described herein are intended only as illustrations of such devices and not as the specifications for such devices. ROHM CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any third party's intellectual property rights or other proprietary rights, and further, assumes no liability of whatsoever nature in the event of any such infringement, or arising from or connected with or related to the use of such devices. Upon the sale of any such devices, other than for buyer's right to use such devices itself, resell or otherwise dispose of the same, implied right or license to practice or commercially exploit any intellectual property rights or other proprietary rights owned or controlled by ROHM CO., LTD. is granted to any such buyer. The products described herein utilize silicon as the main material. The products described herein are not designed to be X ray proof. Published by Application Engineering Group Catalog NO.05T375Be '05.10 ROHM Ⓒ 8/8 Appendix Notes No technical content pages of this document may be reproduced in any form or transmitted by any means without prior permission of ROHM CO.,LTD. The contents described herein are subject to change without notice. The specifications for the product described in this document are for reference only. Upon actual use, therefore, please request that specifications to be separately delivered. Application circuit diagrams and circuit constants contained herein are shown as examples of standard use and operation. Please pay careful attention to the peripheral conditions when designing circuits and deciding upon circuit constants in the set. Any data, including, but not limited to application circuit diagrams information, described herein are intended only as illustrations of such devices and not as the specifications for such devices. ROHM CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any third party's intellectual property rights or other proprietary rights, and further, assumes no liability of whatsoever nature in the event of any such infringement, or arising from or connected with or related to the use of such devices. Upon the sale of any such devices, other than for buyer's right to use such devices itself, resell or otherwise dispose of the same, no express or implied right or license to practice or commercially exploit any intellectual property rights or other proprietary rights owned or controlled by ROHM CO., LTD. is granted to any such buyer. Products listed in this document are no antiradiation design. The products listed in this document are designed to be used with ordinary electronic equipment or devices (such as audio visual equipment, office-automation equipment, communications devices, electrical appliances and electronic toys). Should you intend to use these products with equipment or devices which require an extremely high level of reliability and the malfunction of which would directly endanger human life (such as medical instruments, transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers and other safety devices), please be sure to consult with our sales representative in advance. It is our top priority to supply products with the utmost quality and reliability. However, there is always a chance of failure due to unexpected factors. Therefore, please take into account the derating characteristics and allow for sufficient safety features, such as extra margin, anti-flammability, and fail-safe measures when designing in order to prevent possible accidents that may result in bodily harm or fire caused by component failure. ROHM cannot be held responsible for any damages arising from the use of the products under conditions out of the range of the specifications or due to non-compliance with the NOTES specified in this catalog. Thank you for your accessing to ROHM product informations. More detail product informations and catalogs are available, please contact your nearest sales office. ROHM Customer Support System www.rohm.com Copyright © 2008 ROHM CO.,LTD. THE AMERICAS / EUROPE / ASIA / JAPAN Contact us : webmaster@ rohm.co. jp 21 Saiin Mizosaki-cho, Ukyo-ku, Kyoto 615-8585, Japan TEL : +81-75-311-2121 FAX : +81-75-315-0172 Appendix1-Rev2.0