参数资料
型号: TPA721DRG4
厂商: TEXAS INSTRUMENTS INC
元件分类: 音频/视频放大
英文描述: 0.7 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
封装: GREEN, PLASTIC, MS-012AA, SOIC-8
文件页数: 8/26页
文件大小: 663K
代理商: TPA721DRG4
www.ti.com
f
co(lowpass) +
1
2p R
F
C
F
3 dB
fc
(7)
Input Capacitor, CI
f
co(highpass) +
1
2p R
I
C
I
3 dB
fc
(8)
C
I +
1
2p R
I
fco
(9)
Power Supply Decoupling, CS
TPA721
SLOS231E – NOVEMBER 1998 – REVISED JUNE 2004
For example, if RF is 100 k and CF is 5 pF, then fco 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.
The value of CI is important to consider as it directly affects the bass (low-frequency) performance of the circuit.
Consider the example where RI is 10 k and the specification calls for a flat bass response down to 40 Hz.
Equation 8 is reconfigured as Equation 9.
In this example, CI is 0.40 F; so, one would likely choose a value in the range of 0.47 F to 1 F. A further
consideration for this capacitor is the leakage path from the input source through the input network (RI, CI) and
the feedback resistor (RF) to the load. This leakage current creates a dc offset voltage at the input to the amplifier
that reduces useful headroom, especially in high-gain applications. For this reason a low-leakage tantalum or
ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor
should face the amplifier input in most applications as the dc level there is held at VDD/2, which is likely higher
than the source dc level. It is important to confirm the capacitor polarity in the application.
The TPA721 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to
ensure the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also prevents
oscillations for long lead lengths between the amplifier and the speaker. The optimum decoupling is achieved by
using two capacitors of different types that target different types of noise on the power supply leads. For higher
frequency transients, spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) ceramic
capacitor, typically 0.1 F, placed as close as possible to the device VDD lead, works best. For filtering lower
frequency noise signals, a larger aluminum electrolytic capacitor of 10 F or greater placed near the audio power
amplifier is recommended.
16
相关PDF资料
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TPA731DGNR 0.7 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
TPA731DGN 0.7 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
TPA731DR 0.35 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
TPA731D 0.35 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
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