參數(shù)資料
型號(hào)： LM4867LQ
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 音頻／視頻放大
英文描述： Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function
中文描述： 3 W, 2 CHANNEL, AUDIO AMPLIFIER, PQCC24
封裝： EXPOSED PAD, LLP-24
文件頁(yè)數(shù)： 14/26頁(yè)
文件大?。?/td> 763K
代理商： LM4867LQ
Application Information
(Continued)
Truth Table for Logic Inputs
SHUTDOWN
PIN
Logic Low
Logic Low
Logic Low
Logic Low
Logic High
HP-IN
PIN
MUX CHANNEL
INPUT SELECT
Logic Low
Logic High
Logic Low
Logic High
X
OPERATIONAL MODE (MUX
INPUTCHANNEL #)
Bridged amplifiers (1)
Bridged amplifiers (2)
Single-ended amplifiers (1)
Single-ended amplifiers (2)
Micropower shutdown
= OUTB signal
= OUTB signal
≠
OUTB signal
≠
OUTB signal
X
HP-IN FUNCTION
An internal pullup circuit is connected to the HPIN (pin 20)
headphone amplifier control pin. When this pin is left uncon-
nected, V
is applied to the HPIN. This turns off Amp2B
and switches Amp2A’s input signal from an audio signal to
the V
/2 voltage present on pin 14. The result is muted
bridge-connected loads. Quiescent current consumption is
reduced when the IC is in this singleended mode.
Figure 7 shows the implementation of the LM4867’s head-
phone control function. An internal comparator with a nomi-
nal 400mV offset monitors the signal present at the OUTB
output. It compares this signal against the signal applied to
the HPIN pin. When these signals are equal, as is the case
when a BTL is connected to the amplifier, the comparator
forces the LM4867 to maintain bridgedamplifier operation.
When the HPIN pin is externally floated, such as when
headphones are connected to the jack shown in Figure 7
and internal pullup forces V
on the internal comparator’s
HPIN inputs. This changes the comparator’s output state
and enables the headphone function: it turns off Amp2B,
switches Amp2A’s input signal from an audio signal to the
V
DD
/2
voltage
present
on
bridge-connected loads. Amp1A and Amp1B drive the head-
phones.
Figure 7 also shows the suggested headphone jack electri-
cal connections. The jack is designed to mate with a
threewire plug. The plug’s tip and ring should each carry
one of the two stereo output signals, whereas the sleeve
provides the return to Amp2A. A headphone jack with one
control pin contact is sufficient to drive the HPIN pin when
connecting headphones.
A switch can replace the headphone jack contact pin. When
a switch shorts the HPIN pin to V
, bridgeconnected
speakers are muted and Amp1A and Amp2A drive a pair of
pin
14,
and
mutes
the
headphones. When a switch shorts the HPIN pin to GND,
the LM4867 operates in bridge mode. If headphone drive is
not needed, short the HPIN pin to the OUTB pin.
Single-Ended Output Power Performance and
Measurement Considerations
The LM4867 delivers clean, low distortion SE output power
into loads that are greater than 10
. As an example, output
power for 16
and 32
loads are shown in the
Typical
Performance Characteristic
curves. For loads less than
10
, the LM4876 can typically supply 180mW of low distor-
tion power. However, when higher dissipation is desired in
loads less than 10
, a dramatic increase in THD+N may
occur. This is normal operation and does not indicate that
proper functionality has ceased. When a jump from moder-
ate to excessively high distortion is seen, simply reducing
the output voltage swing will restore the clean, low distortion
SE operation.
The dramatic jump in distortion for loads less than 10
occurs when current limiting circuitry activates. During SE
operation, AMP2A (refer to Figure 4) drives the headphone
sleeve. An on-board circuit monitors this amplifier’s output
current. The sudden increase in THD+N is caused by the
current limit circuitry forcing AMP2A into a highimpedance
output mode. When this occurs, the output waveform has
discontinuities that produce large amounts of distortion. It
has been observed that as the output power is steadily
increased, the distortion may jump from 5% to greater than
35%. Indeed, 10% THD+N may not actually be achievable.
Using the SingleEnded Output for Line Level
Applications
Some samples of the LM4867 may exhibit small amplitude,
high frequency oscillation when the SE output is connected
to a line-level input. This oscillation can be eliminated by
connecting a 5%, 300
resistor betweenAmp2A’s output pin
and each amplifier, AMP1A and AMP1B, output.
L
www.national.com
14
相關(guān)PDF資料
PDF描述
LM4867MT Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function
LM4867MTE Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function
LM4868 Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function
LM4868MTE Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function
LM4868LQ Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM4867LQ/NOPB 制造商:Texas Instruments 功能描述:Audio Amp Headphone/Speaker 2-CH Stereo 3W Class-AB 24-Pin LLP EP T/R
LM4867MT 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function
LM4867MT NOPB 制造商:Texas Instruments 功能描述:Audio Amp Headphone/Speaker 2-CH Stereo 1.5W Class-AB 20-Pin TSSOP Rail
LM4867MT/NOPB 功能描述:IC AMP AUDIO PWR 3W AB 20TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機(jī)，2-通道（立體聲） 在某負(fù)載時(shí)最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點(diǎn):I²C，麥克風(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR)
LM4867MTE 制造商:Texas Instruments 功能描述:Audio Amp Headphone/Speaker 2-CH Stereo 3W Class-AB 20-Pin TSSOP EP Rail
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*