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参数资料
| 型号： | NCP2809BGEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 8/24页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR NCP2809B |
| 设计资源： | NCP2809B Demo Brd Schematic NCP2809B EVB BOM NCP2809BGEVB Gerber Files |
| 标准包装： | 1 |
| 系列： | NOCAP™ |
| 放大器类型： | AB 类 |
| 输出类型： | 耳机，2-通道（立体声） |
| 在某负载时最大输出功率 x 通道数量： | 135mW x 2 @ 16 欧姆 |
| 电源电压： | 2.2 V ~ 5.5 V |
| 板类型： | 完全填充 |
| 已用 IC / 零件： | NCP2809 |
| 已供物品： | 板 |
| 其它名称： | NCP2809BEVBOS NCP2809BEVBOS-ND NCP2809BGEVBOS |
NCP2809 Series
http://onsemi.com
16
Bypass Capacitor Selection (Cbypass)
The bypass capacitor Cby provides halfsupply filtering
and determines how fast the NCP2809 turns on.
A proper supply bypassing is critical for low noise
performance and high power supply rejection ratio.
Moreover, this capacitor is a critical component to
minimize the turnon pop noise. A 1.0
mF bypass capacitor
value should produce clickless and popless shutdown
transitions. The amplifier is still functional with a 0.1
mF
capacitor value but is more sensitive to “pop and click”
noises.
Thus, for optimized performances, a 1.0
mF ceramic
bypassing capacitor is recommended.
Without Output Coupling Capacitor
As described in Figure 42, the internal circuitry of the
NCP2809 device eliminates need of heavy bypassing
capacitors when connecting a stereo headset with 3
connecting points. This circuitry produces a virtual ground
and does not affect either output power or PSRR.
Additionally, eliminating these capacitors reduces cost and
PCB place.
However, user must take care to the connection between
pin REF_I and ground of the headset: this pin is the ground
reference for the headset. So, in order to improve
crosstalk performances, this pin must be plugged
directly to the middle point of the headset connector.
With Output Coupling Capacitor
However, when using a low cost jack connector (with
third connection to ground), the headset amplifier requires
very few external components as described in Figure 43.
Only two external coupling capacitors are needed. The
main concern is in output coupling capacitors, because of
the value and consequently the size of the components
required. Purpose of these capacitors is biasing DC voltage
and very low frequency elimination. Both, coupling
capacitor and output load form a high pass filter. Audible
frequency ranges from 20 Hz to 20 kHz, but headset used
in portable appliance has poor ability to reproduce signals
below 75 or 100 Hz. Input coupling capacitor and input
resistance also form a high pass filter. These two first order
filters form a second order high pass filter with the same
3 dB cut off frequency. Consequently, the below formula
must be followed:
1
2
p
Rin
Cin
[
1
2
p
RL
Cout
(eq. 2)
As for a loudspeaker amplifier, the input impedance
value for calculating filters cut off frequency is the
minimum input impedance value at maximum output
volume.
To obtain a frequency equal to when frequency is 5 times
the cut off frequency, attenuation is 0.5 dB. So if we want
a
±0.5 dB at 150 Hz, we need to have a –3 dB cut off
frequency of 30 Hz:
f3dB w
1
2
p
RL
Cout
(eq. 3)
Cout w
1
2
p
RL
f3dB
(eq. 4)
Cout ≥ 330 mF.
With Cout = 220 mF, ±0.5 dB attenuation frequency will
be 225 Hz with a –3.0 dB cut off frequency of 45 Hz.
Following this, the input coupling capacitor choice is
straightforward. Using formula (2) input coupling
capacitor value would be 68 nF for a 220
mF output
coupling capacitor and 100 nF for a 330
mF output coupling
capacitor.
When using the NCP2809 with this configuration, pins
REF_I and OUT_I must be left unconnected
(see Figure 43).
Optimum Equivalent Capacitance at Output Stage
Cellular phone and wireless portable device designers
normally place several Radio Frequency filtering
capacitors and ESD protection devices between the outputs
and the headset connector. Those devices are usually
connected between amplifier outputs and ground, or
amplifier output and virtual ground. Different headsets
with different impedance can be used with NCP2809. 16,
32 and 64Ohm are standard values. The extra impedance
resulting of parasitic headset inductance and protections
capacitance can affect sound quality.
In order to achieve the best sound quality, we suggest the
optimum value of total equivalent capacitance:
Between each output terminal to the virtual ground
should be less than or equal to 100pF
Between each output terminal to the ground should be
less than or equal to 100pF.
This total equivalent capacitance consists of the radio
frequency filtering capacitors and ESD protection device
equivalent parasitic capacitance. Because of their very low
parasitic capacitance value, diode based ESD protection
are preferred.
If for some reason the above requirements cannot be met,
a series resistor between each NCP2809 output and the
protection device can improve amplifier operation. In
order to keep dynamic output signal range, the resistor
value should be very small compared to the loudspeaker
impedance. For example, a 10Ohm resistor for a 64Ohm
loudspeaker allows up to 400pF parasitic capacitance load.
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相关代理商/技术参数 |
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|---|---|
| NCP2809BMUTXG | 功能描述:音频放大器 HEADSET AUDIO AMPLFR RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| NCP2811 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:NOCAP Advanced Stereo Headphone Amplifier |
| NCP2811ADTBR2G | 功能描述:音频放大器 HEADSET AUDIO AMP RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| NCP2811ADTBRGEVB | 功能描述:BOARD EVAL NCP2811 RoHS:是 类别:编程器，开发系统 >> 评估板 - 音频放大器 系列:* 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- |
| NCP2811AFCT1G | 功能描述:音频放大器 HEADSET AUDIO AMPLIFIER RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
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