ROHM BH7881EFV

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 25C 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&REG SUSPEND
0
-
0.8
V
SP/HP&REG 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.
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Appendix1-Rev2.0