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參數(shù)資料
| 型號： | LM4755MWC |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 11 W, 2 CHANNEL, AUDIO AMPLIFIER, UUC |
| 封裝： | WAFER |
| 文件頁數(shù)： | 19/19頁 |
| 文件大小： | 756K |
| 代理商： | LM4755MWC |
Typical Performance Characteristics(Note 5) (Continued)
Application Information
The LM4755 contains circuitry to pull down the bias line
internally, effectively shutting down the input stage. An ex-
ternal R-C should be used to adjust the timing of the pull-
down. If the bias line is pulled down too quickly, currents
induced in the internal bias resistors will cause a momentary
DC voltage to appear across the inputs of each amplifier’s
internal differential pair, resulting in an output DC shift to-
wards Vsupply. An R-C timing circuit should be used to limit
the pull-down time such that output “pops” and signal
feedthroughs will be minimized. The pull-down timing is a
function of a number of factors, including the internal mute
circuitry, the voltage used to activate the mute, the bias
capacitor, the half-supply voltage, and internal resistances
used in the half-supply generator.
Table 1 shows a list of
recommended values for the external R-C.
TABLE 1. Recommended Values for Mute Circuit
V
MUTE
V
CC
Rm
Cm
5V
12V
18 k
10 F
5V
15V
18 k
10 F
5V
20V
12 k
10 F
5V
24V
12 k
10 F
5V
28V
8.2 k
10 F
5V
30V
8.2 k
10 F
CAPACITOR SELECTION AND FREQUENCY
RESPONSE
With the LM4755, as in all single supply amplifiers, AC
coupling capacitors are used to isolate the DC voltage
present at the inputs (pins 3, 7) and outputs (pins 1, 8). As
mentioned earlier in the External Components section
these capacitors create high-pass filters with their corre-
sponding input/output impedances. The Typical Applica-
tion Circuit shown in
Figure 1 shows input and output
capacitors of 0.1 F and 1,000 F respectively. At the input,
with an 83 k
typical input resistance, the result is a high
pass 3 dB point occurring at 19 Hz. There is another high
pass filter at 39.8 Hz created with the output load resistance
of 4
. Careful selection of these components is necessary to
ensure that the desired frequency response is obtained. The
Frequency Response curves in the Typical Performance
Characteristics section show how different output coupling
capacitors affect the low frequency roll-off.
OPERATING IN BRIDGE-MODE
Though designed for use as a single-ended amplifier, the
LM4755 can be used to drive a load differentially (bridge-
mode). Due to the low pin count of the package, only the
non-inverting inputs are available. An inverted signal must
be provided to one of the inputs. This can easily be done with
the use of an inexpensive op-amp configured as a standard
inverting amplifier. An LF353 is a good low-cost choice. Care
must be taken, however, for a bridge-mode amplifier must
theoretically dissipate four times the power of a single-ended
type. The load seen by each amplifier is effectively half that
of the actual load being used, thus an amplifier designed to
drive a 4
load in single-ended mode should drive an 8
load when operating in bridge-mode.
Power Dissipation vs Output Power
DS100059-60
Power Dissipation vs Output Power
DS100059-61
LM4755
www.national.com
9
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM4755T | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Stereo 11W Audio Power Amplifier with Mute |
| LM4755T/NOPB | 功能描述:IC AMP AUDIO PWR 11W AB TO220-9 RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:- 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) |
| LM4755T/NOPB | 制造商:Texas Instruments 功能描述:Audio Power Amplifier IC |
| LM4755TS | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| LM4755TS/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
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