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参数资料
| 型号： | LM4755MDC |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 音频／视频放大 |
| 英文描述： | 11 W, 2 CHANNEL, AUDIO AMPLIFIER, UUC |
| 封装： | DIE |
| 文件页数： | 19/19页 |
| 文件大小： | 756K |
| 代理商： | LM4755MDC |
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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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM4755T | 制造商:NSC 制造商全称: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 类别:集成电路 (IC) >> 线性 - 音頻放大器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:DirectDrive® 类型:H 类 输出类型:耳机，2-通道（立体声） 在某负载时最大输出功率 x 通道数量:35mW x 2 @ 16 欧姆 电源电压:1.62 V ~ 1.98 V 特点:I²C，麦克风，静音，短路保护，音量控制 安装类型:表面贴装 供应商设备封装:25-WLP（2.09x2.09） 封装/外壳:25-WFBGA，WLCSP 包装:带卷 (TR) |
| LM4755T/NOPB | 制造商:Texas Instruments 功能描述:Audio Power Amplifier IC |
| LM4755TS | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| LM4755TS/NOPB | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
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