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参数资料
| 型号： | LM4913MH/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 音频／视频放大 |
| 英文描述： | 0.09 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO10 |
| 封装： | TSSOP-10 |
| 文件页数： | 2/18页 |
| 文件大小： | 1078K |
| 代理商： | LM4913MH/NOPB |
Application Information
20061799
FIGURE 2. Typical Audio Amplifier Application Circuit
BRIDGE (BTL) OR SINGLE-ENDED (SE)
CONFIGURATION EXPLANATION
As shown in Figure 2, the LM4913 consists of two input mul-
tiplexers (MUX) and two power amplifiers designed to drive
loads that have a minimum impedance of 4 ohms. In mono
BTL mode, AMP1 and AMP2 drive a speaker connected be-
tween their outputs. In stereo SE mode, AMP1 and AMP2
each drive a SE load such as stereo headphones.
In mono BTL mode, R1 works with one of AMP1's internal
62.5
feedback resistors to set this amplifier's gain. AMP2
operates unity gain, set by two internal 20k
resistors. In
stereo SE modes, R2 and R3 work with AMP1's and AMP2's
internal 62.5k
feedback resistors to set each amplifier's
gain. The LM4913 drives a BTL load, such as a speaker, con-
nected between AMP1's and AMP2's outputs. Two SE loads
can also be connected to the LM4913's outputs, one driven
by AMP1 and the other driven by AMP2.
When the LM4913 operates in BTL mode, AMP1's output
serves as AMP2's input through AMP2's input MUX. This re-
sults in AMP1 and AMP2 producing signals identical in mag-
nitude, but 180° out of phase. Taking advantage of this phase
difference, a load placed between ROUT/M+ and LOUT/M- is
driven differentially (commonly referred to as "bridge mode").
This results in a differential, or BTL, gain of
A
V (BTL) = -2(AV(SE))
A
V (SE) = -2(62.5k) / Ri
A
V (BTL) = -125k / Ri
(1)
Bridge mode amplifiers are different from single-ended am-
plifiers that drive loads connected between a single amplifier's
output and ground. At any given supply voltage, bridge mode
has a distinct advantage over the single-ended configuration:
its differential output doubles the voltage swing across the
load. Theoretically, this produces four times the output power
when compared to a single-ended, capacitively coupled am-
plifier under the same conditions. This increase in attainable
output power assumes that an amplifier is not current limited
and that the output signal is not clipped. To ensure minimum
output signal clipping when choosing an amplifier's closed-
loop gain, refer to the Audio Power Amplifier Design section.
POWER DISSIPATION
Power dissipation is a major concern when designing a suc-
cessful single-ended or bridged amplifier. Equation (2) states
the maximum power dissipation point for a single-ended am-
plifier operating at a given supply voltage and driving a spec-
ified output load.
P
DMAX-SE = (VDD)
2
/ 2
π2R
L:
Single-Ended
(2)
www.national.com
10
LM4913
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM4913MHX/NOPB | 制造商:Texas Instruments 功能描述:Audio Amp Headphone/Speaker 1-CH Mono/2-CH Stereo 2W Class-AB 10-Pin TSSOP EP T/R |
| LM4913MM | 制造商:NSC 制造商全称:National Semiconductor 功能描述:2W Monaural, 90mW Stereo Headphone Audio Amplifier |
| LM4914 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:1W Monaural, 85mW Stereo Headphone Audio Amplifier |
| LM4914A WAF | 制造商:Texas Instruments 功能描述: |
| LM4914MH | 制造商:NSC 制造商全称:National Semiconductor 功能描述:1W Monaural, 85mW Stereo Headphone Audio Amplifier |
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