Technical Note
2/15
www.rohm.com
2010.10 - Rev.
© 2010 ROHM Co., Ltd. All rights reserved.
BD3870FS,BD3871FS,BD3872FS,BD3873FS
●Electrical characteristics
(Ta=25 ℃ , VCC=8V, f=1kHz, Vi=200mVrms, RL=10kΩ, Rg=600Ω, Input Gain=0dB (BD3870FS, BD3872FS only),
Input Gain=24dB (BD3871FS only), Input Gain=18dB (BD3873FS only),Volume=0dB, Bass=0dB, Treble=0dB,
Surround=OFF, Loud Speaker Equalizer=OFF (BD3872FS only), unless otherwise noted)
Block
Parameter Symbol
Limits
Unit Condition
Min. Typ. Max.
Total
Circuit Current IQ - 8 21 mA At no signal
Total Output Voltage Gain Gv
-2 0 2
dB
BD3870FS, BD3872FS
Gv=20log(VOUT/VIN)
22 24 26
BD3871FS
Gv=20log(VOUT/VIN)
16 18 20
BD3873FS
Gv=20log(VOUT/VIN)
Total Harmonic Distortion ratio THD - 0.01 0.1 % BW=400 to 30kHz
Maximum Output Voltage Vom 1.6 2.1 - Vrms
THD=1%
BW=400 to 30kHz
Total Output Noise Voltage Vno
- 4.5 15
µVrms
BD3870FS, BD3872FS
Rg=0Ω, BW=IHF-A
- 40 80
BD3871FS, BD3873FS
Rg=0Ω, BW=IHF-A
Total Residual Noise Voltage Vmno - 4.5 15 µVrms
Rg=0Ω, BW=IHF-A
Volume=-dB
Cross-talk between Channels CTC - -80 -70 dB
Rg=0Ω, BW=IHF-A
VOUT=1Vrms
Cross-talk between Selectors CTS - -80 -70 dB Rg=0Ω, BW=IHF-A
Input Impedance Rin
35 50 65
kΩ
BD3870FS, BD3871FS, BD3873FS
70 100 130 BD3872FS
Output Impedance Rout - - 50 Ω
Volume
Volume Control Range VRI -90 -87 -84 dB VR=20log(VOUT/VIN)
Maximum Volume Attenuation Vmin - - -90 dB BW=IHF-A
Volume Input Impedance Rvin 39 56 73 kΩ
Bass
Bass Boost Gain GBB 12 14 16 dB GB=20log(VOUT/VIN)
Bass Cut Gain GBC -16 -14 -12 dB GB=20log(VOUT/VIN)
Bass Step Resolution BR - 2 - dB
Treble
Treble Boost Gain GTB
10 12 14
dB
BD3870FS, BD3871FS, BD3873FS
12 14 16 BD3872FS
Treble Cut Gain GTC
-14 -12 -10
dB
BD3870FS, BD3871FS, BD3873FS
-16 -14 -12 BD3872FS
Treble Step Resolution TR - 2 - dB
Surround
Surround In-phase Gain Vsur1 -2 0 2 dB 2ch in-phase inputs
Surround Single-phase Gain Vsur2 4.3 6.3 8.3 dB 1ch input, 1ch grounded
Surround Opposite-phase Gain Vsur3 8 10 12 dB 2ch opposite-phase inputs
SEQ
Loud Speaker Equalizer Gain
(BD3872FS only)
Seq 3 5 7 dB f=10kHz
* For measurement, VP-9690A (Average value wave detection, Effective value display) IHF-A filter by Matsushita Communication Industrial is used.
* Phase relation between Input/Output signal terminals is the same.
* Note: This IC is not designed to be radiation-resistant.