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參數(shù)資料
| 型號： | TEA1085AT |
| 廠商： | NXP SEMICONDUCTORS |
| 元件分類： | 通信及網(wǎng)絡 |
| 英文描述： | Listening-in circuit for line-powered telephone sets |
| 中文描述： | SPECIALTY TELECOM CIRCUIT, PDSO24 |
| 封裝： | PLASTIC, SO-24 |
| 文件頁數(shù)： | 9/32頁 |
| 文件大?。?/td> | 199K |
| 代理商： | TEA1085AT |
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March 1992
9
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
Dynamic limiter (DLC) pin 23
To prevent distortion of the signal at the loudspeaker
outputs the gain of the amplifier is reduced rapidly when:
the peaks of the signal at the loudspeaker outputs
exceed an internally determined threshold (voltage
limiter)
the DC current into SUP is insufficient (current limiter)
the voltage at V
BB
decreases below an internally
determined threshold, typically 2.9 V (V
BB
limiter)
The time in which the gain reduction is effected is the
'attack time'; this is very short in the first and third instance
and relatively long in the second instance. The circuit will
remain in the gain-reduced condition until the peaks of the
output signal remain below the threshold level. The gain
will then return to a nominal level after a time determined
by the capacitor connected to DLC (release time).
MUTE input (MUTE) pin 20; TEA1085A
This MUTE is provided with a logic input to operate with a
microcontroller for instance.
The loudspeaker amplifier is disabled when the MUTE
input is LOW (connected to V
SS
or open input). A HIGH
level at the MUTE input enables the amplifier in the
listening-in mode.
MUTE input (MUTE) pin 20; TEA1085
The MUTE function is provided with a toggle input and is
designed to switch between the standby condition and the
listening-in condition on the rising edge of the input MUTE
signal (see Fig.6).
In the basic application the MUTE input must be LOW
(connected to V
SS
). A simple push-button can be used to
operate the MUTE toggle (see Fig.7). Debouncing can be
realized by means of a small capacitor connected between
MUTE and V
SS
.
An internal start circuit ensures that the circuit always
starts up in the standby condition.
Fig.6 Mute toggle function of the TEA1085.
handbook, full pagewidth
MGR036
LSI1
QLS1
MUTE
standby
standby
listening-in
Fig.7 Mute switch alternatives with the TEA1085.
handbook, full pagewidth
MLA055
MUTE
MUTE
VBB
10 k
(a) Break contact.
(b) Make contact.
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相關代理商/技術參數(shù) |
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| TEA1085T | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Listening-in circuit for line-powered telephone sets |
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| TEA1094 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Hands free IC |
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