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參數(shù)資料
| 型號： | LM4865IBPX/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻控制 |
| 英文描述： | 1 CHANNEL(S), VOLUME CONTROL CIRCUIT, PBGA8 |
| 封裝： | MICRO SMD-8 |
| 文件頁數(shù)： | 15/16頁 |
| 文件大?。?/td> | 512K |
| 代理商： | LM4865IBPX/NOPB |
Typical Performance Characteristics (Continued)
Output Power vs Supply Voltage
10102531
10102532
Supply Current vs Supply Voltage
10102533
Application Information
BRIDGE CONFIGURATION EXPLANATION
As shown in Figure 1, the LM4865 consists of two opera-
tional amplifiers internally. An external DC voltage sets the
closed-loop gain of the first amplifier, whereas two internal
20k
resistors set the second amplifier’s gain at -1. The
LM4865 can be used to drive a speaker connected between
the two amplifier outputs or a monaural headphone con-
nected between V
O1 and GND.
Figure 1 shows that the output of Amp1 serves as the input
to Amp2. This results in both amplifiers producing signals
that are identical in magnitude, but 180 out of phase.
Taking advantage of this phase difference, a load placed
between V
O1 and VO2 is driven differentially (commonly
referred to as “bridge mode“ ). This mode is different from
single-ended driven loads that are connected between a
single amplifier’s output and ground.
Bridge mode has a distinct advantage over the single-ended
configuration: its differential drive to the load doubles the
output swing for a specified supply voltage. This results in
four times the output power when compared to a
single-ended amplifier under the same conditions. This in-
crease in attainable output assumes that the amplifier is not
current limited or 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 De-
sign section.
Another advantage of the differential bridge output is no net
DC voltage across load. This results from biasing V
O1 and
V
O2 at half-supply. This eliminates the coupling capacitor
that single supply, single-ended amplifiers require. Eliminat-
ing an output coupling capacitor in a single-ended configu-
ration forces a single supply amplifier’s half-supply bias volt-
age across the load. The current flow created by the
half-supply bias voltage increases internal IC power dissipa-
tion and may permanently damage loads such as speakers.
POWER DISSIPATION
Power dissipation is a major concern when designing a
successful bridged or single-ended amplifier. Equation (1)
states
the
maximum
power
dissipation
point
for
a
single-ended amplifier operating at a given supply voltage
and driving a specified output load.
P
DMAX =(VDD)
2/(2
π2R
L)
Single-Ended
(1)
However, a direct consequence of the increased power de-
livered to the load by a bridge amplifier is an increase in
internal power dissipation point for a bridge amplifier oper-
ating at the same given conditions.
P
DMAX = 4*(VDD)
2/(2
π2R
L)
Bridge Mode
(2)
The LM4865 has two operational amplifiers in one package
and the maximum internal power dissipation is 4 times that
LM4865
www.national.com
8
相關PDF資料 |
PDF描述 |
|---|---|
| LM4865IBPX | 1 CHANNEL(S), VOLUME CONTROL CIRCUIT, PBGA8 |
| LM4865MDC | 1 CHANNEL(S), VOLUME CONTROL CIRCUIT, UUC |
| LM4865MWC | 1 CHANNEL(S), VOLUME CONTROL CIRCUIT, UUC |
| LM4866MTE/NOPB | 3.2 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20 |
| LM4866MT/NOPB | 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM4865M | 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 |
| LM4865M | 制造商:Texas Instruments 功能描述:AMP AUDIO/VOLT CONTROL 0.75W 4865 |
| LM4865M/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 |
| LM4865MM | 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 |
| LM4865MM/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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