參數(shù)資料
型號: TPA721DG4
廠商: TEXAS INSTRUMENTS INC
元件分類: 音頻/視頻放大
英文描述: 0.7 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
封裝: GREEN, PLASTIC, MS-012AA, SOIC-8
文件頁數(shù): 4/26頁
文件大小: 663K
代理商: TPA721DG4
www.ti.com
APPLICATION INFORMATION
BRIDGE-TIED LOAD
Power +
V
(RMS)
2
R
L
V
(RMS) +
V
O(PP)
2 2
(1)
RL
2x VO(PP)
VO(PP)
–VO(PP)
VDD
f
(corner) +
1
2p R
L
C
(2)
TPA721
SLOS231E – NOVEMBER 1998 – REVISED JUNE 2004
Figure 23 shows a linear audio power amplifier (APA) in a BTL configuration. The TPA721 BTL amplifier consists
of two linear amplifiers driving both ends of the load. There are several potential benefits to this differential drive
configuration, but initially consider power to the load. The differential drive to the speaker means that as one side
is slewing up, the other side is slewing down, and vice versa. This, in effect, doubles the voltage swing on the
load as compared to a ground-referenced load. Plugging 2
× V
O(PP) into the power equation, where voltage is
squared, yields 4
× the output power from the same supply rail and load impedance (see Equation 1).
Figure 23. Bridge-Tied Load Configuration
In a typical portable handheld equipment sound channel operating at 3.3 V, bridging raises the power into an 8-
speaker from a singled-ended (SE, ground reference) limit of 62.5 mW to 250 mW. In sound power, that is a
6-dB improvement, which is loudness that can be heard. In addition to increased power, there are frequency
response concerns. Consider the single-supply SE configuration shown in Figure 24. A coupling capacitor is
required to block the dc offset voltage from reaching the load. These capacitors can be quite large
(approximately 33 F to 1000 F) so they tend to be expensive, heavy, occupy valuable PCB area, and have the
additional drawback of limiting low-frequency performance of the system. This frequency-limiting effect is due to
the high-pass filter network created with the speaker impedance and the coupling capacitance and is calculated
with Equation 2.
For example, a 68-F capacitor with an 8-
speaker would attenuate low frequencies below 293 Hz. The BTL
configuration cancels the dc offsets, which eliminates the need for the blocking capacitors. Low-frequency
performance is then limited only by the input network and speaker response. Cost and PCB space are also
minimized by eliminating the bulky coupling capacitor.
12
相關PDF資料
PDF描述
TPA721DGNG4 0.7 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
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TPA721DGNRG4 功能描述:音頻放大器 Mono Class-AB w/Active HIgh Shtdwn RoHS:否 制造商:STMicroelectronics 產品: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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