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參數(shù)資料
| 型號： | LM4831VF |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 消費家電 |
| 英文描述： | Multimedia Computer Audio Chip |
| 中文描述： | SPECIALTY CONSUMER CIRCUIT, PQFP44 |
| 封裝： | TQFP-44 |
| 文件頁數(shù)： | 10/12頁 |
| 文件大?。?/td> | 575K |
| 代理商： | LM4831VF |
Typical Performance Characteristic
(Continued)
Application Information
GROUNDING
Certain grounding techniques should be followed when lay-
ing out the LM4831 circuit. Figure 4 shows how to setup the
grounds for the LM4831. The half-supply bypass ground
should be tied with the input source grounds and brought
back to the power supply ground separately from the output
load grounds. in with the input grounds. Bringing the output
load grounds back to the supply separately will keep large
signal currents from interfering with the stable input ground
references.
LAYOUT
As stated in the Grounding section, placement of ground re-
turn lines is critical for maintaining the highest level of sys-
tem performance. It is not only important to route the correct
ground return lines together, but also important to be aware
of where those ground return lines are routed relative to
each other. The output load ground returns should be physi-
cally located as far as reasonably possible from low signal
level lines and their ground return lines. The layout of the mi-
crophone amplifier signal lines is critical, since these lines
generally work at very low signal levels.
SUPPLY BYPASSING
As with all op amps and power op amps, the LM4831 re-
quires the power supplies to be bypassed to reduce distor-
tion and avoid oscillation. To avoid high frequency instabili-
ties, a 0.1μF metallized-film or ceramic capacitor should be
used to bypass each supply pin as near to the chip as pos-
sible. For low frequency considerations, a 10μF or greater
tantalum or electrolytic capacitor should be paralleled with
the high frequency bypass capacitor.
If power supply bypass capacitors are not sufficiently large,
the current in the power supply leads, which is a rectified ver-
sion of the output current, may be fed back into internal cir-
cuitry. This internal feedback signal can cause high fre-
quency distortion and oscillation.
If power supply lines to the chip are long, larger bypass ca-
pacitors could be required. Long power supply leads have in-
ductance and resistance associated with them, which could
prevent peak low frequency current demands from being
met. The extra bypass capacitance will reduce the peak cur-
rent requirements from the power supply lines.
Under certain conditions, the LM4831 may refuse to come
out of shutdown. A 1M
resistor connected from the power
supply to the bypass pin, as shown in the
Typical Applica-
tion
section circuit, Figure 3 will guarantee startup.
CLICK & POP CIRCUITRY AND THE BYPASS
CAPACITOR
The LM4831 contains circuitry to minimize turn-on tran-
sients. In this case, turn-on refers to either power supply
turn-on or the device coming out of shutdown mode. During
turn-on, an internal current source charges the bypass ca-
pacitor on the bypass pin. Both the inputs and outputs track
the voltage at the bypass pin. As soon as the bypass node is
stable at 1/2 V
DD
, the amplifier will become fully operational.
Although the bypass pin current source cannot be modified,
the size of the bypass capacitor, Cb, can be changed to alter
the device turn-on time and the amount of “click and pop”.
The relationship between the size of Cb and the turn-on time
is linear. By increasing Cb, the amount of turn-on pop can be
reduced. However, the trade-off for using a larger bypass ca-
pacitor is an increase in the turn-on time for the device. Re-
Equalizer Output
Noise Floor
DS100057-8
DS100057-99
FIGURE 4. Grounding Strategy for LM4831
www.national.com
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PDF描述 |
|---|---|
| LM4831 | Multimedia Computer Audio Chip |
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| LM4832 | Digitally Controlled Tone and Volume Circuit with Stereo Audio Power Amplifier, Microphone Preamp Stage and National 3D Sound |
| LM4832M | Digitally Controlled Tone and Volume Circuit with Stereo Audio Power Amplifier, Microphone Preamp Stage and National 3D Sound |
| LM4832N | Digitally Controlled Tone and Volume Circuit with Stereo Audio Power Amplifier, Microphone Preamp Stage and National 3D Sound |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM4831VFX | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Texas Instruments 功能描述: |
| LM4832 | 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 | 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(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機(jī)，2-通道（立體聲） 在某負(fù)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(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)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(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機(jī)，2-通道（立體聲） 在某負(fù)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(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
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