參數(shù)資料
型號: TPA741D
廠商: TEXAS INSTRUMENTS INC
元件分類: 音頻/視頻放大
英文描述: 0.35 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
封裝: GREEN, PLASTIC, MS-012AA, SOIC-8
文件頁數(shù): 7/27頁
文件大?。?/td> 760K
代理商: TPA741D
www.ti.com
COMPONENT SELECTION
Gain-Setting Resistors, RF and RI
BTL gain + * 2
R
F
R
I
(5)
Effective impedance +
R
F
R
I
R
F )
R
I
(6)
(7)
fc +
1
2p R
F
C
F
3 dB
fc
(7)
Input Capacitor, CI
TPA741
SLOS316C – JUNE 2000 – REVISED JUNE 2004
The gain for each audio input of the TPA741 is set by resistors RF and RI according to Equation 5 for BTL mode.
BTL mode operation brings about the factor 2 in the gain equation due to the inverting amplifier mirroring the
voltage swing across the load. Given that the TPA741 is an MOS amplifier, the input impedance is high;
consequently, input leakage currents are not generally a concern, although noise in the circuit increases as the
value of RF increases. In addition, a certain range of RF values is required for proper start-up operation of the
amplifier. Taken together, it is recommended that the effective impedance seen by the inverting node of the
amplifier be set between 5 k
and 20 k. The effective impedance is calculated in Equation 6.
As an example, consider an input resistance of 10 k
and a feedback resistor of 50 k. The BTL gain of the
amplifier would be -10 V/V and the effective impedance at the inverting terminal would be 8.3 k
, which is well
within the recommended range.
For high-performance applications, metal film resistors are recommended because they tend to have lower noise
levels than carbon resistors. For values of RF above 50 k, the amplifier tends to become unstable due to a pole
formed from RF and the inherent input capacitance of the MOS input structure. For this reason, a small
compensation capacitor of approximately 5 pF should be placed in parallel with RF when RF is greater than 50
k
. This, in effect, creates a low-pass filter network with the cutoff frequency defined in Equation 7.
For example, if RF is 100 k and CF is 5 pF, then fc is 318 kHz, which is well outside of the audio range.
In the typical application an input capacitor, CI, is required to allow the amplifier to bias the input signal to the
proper dc level for optimum operation. In this case, CI and RI form a high-pass filter with the corner frequency
determined in Equation 8.
15
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TPA741DGNG4 功能描述:音頻放大器 Mono Diff Input Class-AB 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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel
TPA741DGNR 功能描述:音頻放大器 Mono Diff Input Class-AB 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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel
TPA741DGNRG4 功能描述:音頻放大器 Mono Diff Input Class-AB 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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel