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參數(shù)資料
| 型號： | LM4832 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Digitally Controlled Tone and Volume Circuit with Stereo Audio Power Amplifier, Microphone Preamp Stage and National 3D Sound |
| 中文描述： | 數(shù)字控制音調(diào)和音量立體聲功放，麥克風前置放大器和國家舞臺3D音效電路 |
| 文件頁數(shù)： | 14/22頁 |
| 文件大小： | 688K |
| 代理商： | LM4832 |
Application Information
(Continued)
I
2
C INTERFACE
The LM4832 uses a serial bus, which conforms to the I
2
C
protocol, to control the chip’s functions with two wires: clock
and data. The clock line is uni-directional. The data line is bi-
directional(open-collector) with a pullup resistor (typically
10 k
).The maximum clock frequency specified by the I
2
C
standard is 400 kHz. In this discussion, the master is the
controlling microcontroller and the slave is the LM4832.
The I
2
C address for the LM4832 is determined using the Ad-
dress Bit 1 and Address Bit 2 TTL/CMOS inputs on the chip.
The LM4832’s four possible I
2
C chip addresses are of the
form 10000X
X
0 (binary), where the X
and X
bits are de-
termined by the voltage levels at the Address Bit 2 and Ad-
dress Bit 1 pins, respectively. If the I
2
C interface is used to
address a number of chips in a system and the LM4832’s
chip address can be changed to avoid address conflicts.
The timing diagram for the I
2
C is shown in Figure 2 The data
is latched in on the stable high level of the clock and the data
line should be held high when not in use. The timing diagram
is broken up into six major sections:
The “start” signal is generated by lowering the data signal
while the clock signal is high. The start signal will alert all de-
vices attached to the I
2
C bus to check the incoming address
against their own chip address.
The 8-bit chip address is sent next, most significant bit first.
Each address bit must be stable while the clock level is high.
After the last bit of the address is sent, the master checks for
the LM4832’s acknowledge. The master releases the data
line high (through a pullup resistor). Then the master sends
a clock pulse. If the LM4832 has received the address cor-
rectly, then it holds the data line low during the clock pulse.
If the data line is not low, then the master should send a
“stop” signal (discussed later) and abort the transfer.
The 8 bits of data are sent next, most significant bit first.
Each data bit should be valid while the clock level is stable
high.
After the data byte is sent, the master must generate another
acknowledge to see if the LM4832 received the data.
If the master has more data bytes to send to the LM4832,
then the master can repeat the previous two steps until all
data bytes have been sent.
The “stop” signal ends the transfer. To signal “stop”, the data
signal goes high while the clock signal is high.
3D AUDIO ENHANCEMENT
The LM4832 has a 3D audio enhancement effect that helps
improve the apparent stereo channel separation when, be-
cause of cabinet or equipment limitations, the left and right
speakers are closer to each other than optimal.
An external RC network, shown in Figure 3 is required to en-
able the effect. The amount of the effect is set by the 20 k
resistor.A0.1 μF capacitor is used to reduce the effect at fre-
quencies below 80 Hz. Decreasing the resistor size will
make the 3D effect more pronounced and decreasing the ca-
pacitor size will raise the cutoff frequency for the effect.
The 680 k
resistor across the 0.1 μF capacitor reduces
switching noise by discharging the capacitor when the effect
is not in use.
TONE CONTROL RESPONSE
Bass and treble tone controls are included in the LM4832.
The tone controls use two external capacitors for each ste-
reo channel. Each has a corner frequency determined by the
value of C2 and C3 (see Figure 4) and internal resistors in
the feedback loop of the internal tone amplifier.
Typically, C2 = C3 and for 100 Hz and 10 kHz corner fre-
quencies, C2 = C3 = 0.0082 μF. Altering the ratio between
C2 and C3, changes the midrange gain. For example, if C2
= 2(C3), then the frequency response will be flat at 20 Hz
and 20 kHz, but will have a 6 dB peak at 1 kHz.
With C = C2 = C3, the treble turn-over frequency is nominally
f
TT
= 1/(2
π
C(14 k
))
and the bass turn-over frequency is nominally
f
BT
= 1/(2
π
C(30.4 k
)),
when maximum boost is chosen. The inflection points (the
frequencies where the boost or cut is within 3 dB of the final
value) are, for treble and bass respectively,
f
TI
= 1/(2
π
C(1.9 k
))
f
BI
= 1/(2
π
C(169.6 k
))
Increasing the values of C2 and C3 decreases the turnover
and inflection frequencies: i.e., the Tone Control Response
Curves shown in
Typical Performance Section
will shift left
when C2 and C3 are increased and shift right when C2 and
C3 are decreased. With C2 = C3 = 0.0082 μF, 2 dB steps are
achieved at 100 Hz and 10 kHz. Changing C2 and C3 to
0.01 μF shifts the 2 dB step frequency to 72 Hz and 8.3
kHz.If the tone control capacitors’ size is decreased these
frequencies will increase.With C2 = C3 = 0.0068 μF the 2 dB
steps take place at 130 Hz and 11.2 kHz.
DS100014-28
FIGURE 5. 3D Effect Components
www.national.com
14
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相關代理商/技術參數(shù) |
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| LM4832M | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Digitally Controlled Tone and Volume Circuit with Stereo Audio Power Amplifier, Microphone Preamp Stage and National 3D Sound |
| LM4832M/NOPB | 功能描述:IC AMP AUDIO PWR .25W AB 28SOIC RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機，2-通道（立體聲） 在某負載時最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點:I²C，麥克風，靜音，短路保護，音量控制 安裝類型:表面貼裝 供應商設備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4832MT/NOPB | 功能描述:IC AMP AUDIO PWR .25W AB 28TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機，2-通道（立體聲） 在某負載時最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點:I²C，麥克風，靜音，短路保護，音量控制 安裝類型:表面貼裝 供應商設備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4832MTX/NOPB | 功能描述:IC AMP AUDIO PWR .25W AB 28TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機，2-通道（立體聲） 在某負載時最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點:I²C，麥克風，靜音，短路保護，音量控制 安裝類型:表面貼裝 供應商設備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4832MX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Digitally Controlled Tone and Volume Circuit with Stereo Audio Power Amplifier, Microphone Preamp Stage and National 3D Sound |
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