参数资料
| 型号： | NCP4894MNR2 |
| 厂商： | ON Semiconductor |
| 文件页数： | 4/19页 |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO PWR 1W DIFF 10-DFN |
| 产品变化通告： | LTB Notification 03/Jan/2008 |
| 标准包装： | 3,000 |
| 类型： | AB 类 |
| 输出类型： | 1-通道（单声道） |
| 在某负载时最大输出功率 x 通道数量： | 1.8W x 1 @ 8 欧姆 |
| 电源电压： | 2.2 V ~ 5.5 V |
| 特点： | 消除爆音，差分输入，短路和热保护，关闭 |
| 安装类型： | 表面贴装 |
| 供应商设备封装： | 10-DFN（3x3） |
| 封装/外壳： | 10-VFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
NCP4894
http://onsemi.com
12
APPLICATION INFORMATION
Detailed Description
The NCP4894 audio amplifier can operate under 2.6 V
until 5.5 V power supply. It delivers 320 mW rms output
power to 4.0
W load (VP = 2.6 V) and 1.0 W rms output
power to 8.0
W load (VP = 5.0 V).
The structure of the NCP4894 is basically composed of
two identical internal power amplifiers. Both are externally
configurable with gainsetting resistors Rin and Rf (the
closedloop gain is fixed by the ratios of these resistors).
The load is driven differentially through OUTA and OUTB
outputs. This configuration eliminates the need for an
output coupling capacitor.
Internal Power Amplifier
The output PMOS and NMOS transistors of the amplifier
were designed to deliver the output power of the
specifications without clipping. The channel resistance
(Ron) of the NMOS and PMOS transistors does not exceed
0.6
W when they drive current.
The structure of the internal power amplifier is
composed of three symmetrical gain stages, first and
medium gain stages are transconductance gain stages to
obtain maximum bandwidth and DC gain.
TurnOn and TurnOff Transitions
A cycle with a turnon and turnoff transition is
illustrated with plots that show both single ended signals on
the previous page.
In order to eliminate “pop and click” noises during
transitions, output power in the load must be slowly
established or cut. When logic high is applied to the
shutdown
pin, the bypass voltage begins to rise
exponentially and once the output DC level is around the
common mode voltage, the gain is established slowly
(20 ms). Using this turnon mode, the device is optimized
in terms of rejection of “pop and click” noises.
A theoretical value of turnon time at 25
°C is given by
the following formula.
Cby: bypass capacitor
R: internal 150 k resistor with a 25% accuracy
Ton = 0.95 * R * Cby
The device has the same behavior when it is turnedoff
by a logic low on the shutdown pin. During the shutdown
mode, amplifier outputs are connected to the ground.
However, to totally cut the output audio signal, you only
need to wait for 20 ms.
Shutdown Function
The device enters shutdown mode once the SD SELECT
and SD MODE pins are in the same logic state. This brings
flexibility to the design, as the SD MODE pin must be
permanently connected to VP or GND on the PCB. If the
SD SELECT pin is not connected to the output of a
microcontroller or microprocessor, it’s not advisable to let
it float. A pulldown or pullup resistor is then suitable.
During the shutdown state, the DC quiescent current has a
typical value of 10 nA.
Current Limit Circuit
The
maximum
output
power
of
the
circuit
(Porms = 1.0 W, VP = 5.0 V, RL = 8.0
W) requires a peak
current in the load of 500 mA.
In order to limit the excessive power dissipation in the
load when a shortcircuit occurs between both outputs, the
current limit in the load is fixed to 800 mA.
Thermal Overload Protection
Internal
amplifiers
are
switched
off
when
the
temperature exceeds 160
°C, and will be switched on again
only when the temperature decreases below 140
°C.
The NCP4894 is unitygain stable and requires no
external components besides gainsetting resistors, an
input coupling capacitor and a proper bypassing capacitor
in the typical application.
Both internal amplifiers are externally configurable (Rf
and Rin) with gain configuration.
The differentialended amplifier presents two major
advantages:
The possible output power is four times larger (the
output swing is doubled) as compared to a singleended
amplifier under the same conditions.
Output pins (OUTA and OUTB) are biased at the same
potential VP/2, this eliminates the need for an output
coupling
capacitor required with a singleended
amplifier configuration.
The differential closed loopgain of the amplifier is
given by Avd + *
Rf
Rin
+
Vorms
Vinrms
.
Vorms is the rms value of
the voltage seen by the load and Vinrms is the rms value of
the input differential signal.
Output power delivered to the load is given by
Porms +
(Vopeak)2
2* RL
(Vopeak is the peak differential
output voltage).
When choosing gain configuration to obtain the desired
output power, check that the amplifier is not current limited
or clipped.
The maximum current which can be delivered to the load
is 500 mA Iopeak +
Vopeak
RL
.
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| NCP4894MNR2G | 功能描述:音频放大器 1.8W Diff Audio PWR Industrial Temp 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 |
| NCP4896 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:1.0 Watt Audio Power Amplifier with Earpiece Driving Capability |
| NCP4896/D | 制造商:未知厂家 制造商全称:未知厂家 功能描述:1W Audio Amplifier with Earpiece Driving Capability |
| NCP4896EVB | 功能描述:音频 IC 开发工具 ANA NCP4896 EVAL BRD RoHS:否 制造商:Texas Instruments 产品:Evaluation Kits 类型:Audio Amplifiers 工具用于评估:TAS5614L 工作电源电压:12 V to 38 V |
| NCP4896FCT1G | 功能描述:音频放大器 1W Audio w/EarPiece Driving Ind. Temp 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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