BH3852FS [ROHM]
Sound control IC; 声音控制IC
| 型号： | BH3852FS |
| 厂家： | 
ROHM |
| 描述： | Sound control IC |
| 文件： | 总11页 (文件大小：198K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Audio ICs
Sound control IC
BH3852S / BH3852FS
The BH3852S and BH3852FS are signal processing ICs designed for volume and tone control in CD radio cassettes
and other audio products. They can be used without a microcomputer because they use DC current for control.
FApplications
CDradiocassettes, microcomponents, carstereos, tele-
visions
FFeatures
1) Can control volume (main volume) and tone (bass,
treble).
3) Input amp can be used for gain adjustment, and ma-
trix surround yields powerful sound.
2) Volume is produced by a low-distortion, low-noise
VCA, is controlled with DC current, and, due to an in-
ternal reference voltage with temperature com-
pensation, can control two channels with a single
variable resistor.
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions
611
Audio ICs
BH3852S / BH3852FS
FBlock diagram
FPin descriptions
612
Audio ICs
BH3852S / BH3852FS
FInput / output circuits
613
Audio ICs
BH3852S / BH3852FS
614
Audio ICs
BH3852S / BH3852FS
FElectrical characteristics(unless otherwise noted, Ta = 25_C, VCC = 8V, f = 1kHz, BW = 20 X 20kHz,
VOL = Max., TONE = ALL FLAT, Rg = 600Ω, RL = 10kΩ, INPUT_AMP_GAIN = 0dB)
615
Audio ICs
BH3852S / BH3852FS
FMeasurement circuit
616
Audio ICs
BH3852S / BH3852FS
FApplication example
617
Audio ICs
BH3852S / BH3852FS
FOperation notes
(1) Operating power supply voltage range
As long as the operating power supply voltage range and
ambient temperature are kept within the specified range,
the basic circuits are guaranteed to function, but be sure
to check the constants as well as the element settings,
voltage settings, and temperature settings. Also, volume
curves sometimes depart from target values when there
is a combination of low temperature and reduced power.
(2) Primary amp
S The input impedance is 47kΩ.
S A buffer if R and C1 are not present.
S The gain can be set by R and the 20kΩ.
GVC = (R + 20kΩ) / R
Note: Set C2 (input coupling) and C1 (used to set the
gain) depending on the frequency band used.
(3) Bass filter
S The BPF is composed of a multifeedback active filter.
fo can be varied according to the value of C.
(theoretical equation)
1
1
*
1
1
2π
R2
1
R1
2
2
fO =
G =
Q
(C1)C2)
R1R2C1C2
R2C1C2
*
1
C1
Note: Filter gain is calculated using the equation on the left. Total output gain is the
1)
sum of the gain for each of the internal circuits.
5kΩ
C2
(When R1 = 11.5kΩ, R2 = 85kΩ, C1 = C2 = C)
5.1 10*
6
fO =
Q = 1.36 G = 8.5
C
618
Audio ICs
BH3852S / BH3852FS
(4) Treble filter
S Cutoff frequency (fC1) for the bypass filter can be
changed using the attached C3.
1
fC1 =
2π C3 2kΩ
The fC1 for the recommended constant is
approximately 8 kHz.
S fC2 is determined by the band of the built-in amp.
fC2 is approximately 100 kHz.
Tone control is designed to yield a variation of
±15dB (Typ.) when the frequency to be boosted or
cut is at the peak or bottom of the filter frequency
characteristic, so please take the frequency charac-
teristic into consideration in designing the filter.
(5) Signal level setting
The following figure represents the standard setting for
the BH3852FS / BH3852S.
LAs indicated above, if the front volume and rear volume
input level are set so as not to exceed +6dBV (2Vrms),
the pre-amp gain setting can be used to improve the S/N
ratio.
619
Audio ICs
BH3852S / BH3852FS
(6) Matrix surround
(7) DC control
ItisrecommendedthatDCcontroloftheVC, TC, BC, and
SC pins be performed by voltage delivered in variable
volume from the Vref pin (12th pin). When using variable
volume, take the discharge current of each pin into ac-
count in determining its settings.
Note:The voltage range for DC control is 0 (V) to Vref (V).
Be sure not to apply voltage greater than Vref (V) to any
pin.
(8) GND
Thown in the
figure above. Use the equations shown in the figure to
calculate gain.
If several capacitors with good high-frequency charac-
teristics are connected in parallel to the 12th-pin capaci-
tor, the characteristics will be improved with respect to
static electricity noise. (Recommended : ceramic capaci-
tors of 0.001µF to 0.1µF)
620
Audio ICs
BH3852S / BH3852FS
FElectrical characteristic curves
FExternal dimensions (Units: mm)
621
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