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參數(shù)資料
| 型號： | MC34118DW |
| 廠商： | Freescale Semiconductor |
| 文件頁數(shù)： | 2/22頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC VOICE SWITCH SPKPHONE 28-SOIC |
| 標(biāo)準(zhǔn)包裝： | 26 |
| 功能： | 語音切換式揚聲電話 |
| 電路數(shù)： | 1 |
| 電源電壓： | 3.5 V ~ 6.5 V |
| 電流 - 電源： | 5.5mA |
| 工作溫度： | -20°C ~ 60°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 28-SOIC（0.295"，7.50mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 28-SOIC W |
| 包裝： | 管件 |
| 包括： | 背景噪聲監(jiān)視器，芯片禁用，撥號音調(diào)檢測器，驅(qū)動器放大器，電平檢測器，麥克風(fēng)放大器，靜音 |
MC34118
MOTOROLA
10
— To switch to idle quickly (fast idle), the current sources
are turned off, and the internal 2.0 k resistor is switched
in, discharging the capacitor to VB with a time constant
=2.0 kxCT.
— To switch to idle slowly (slow idle), the current sources
are turned off, the switch at the 2.0 k resistor is open,
and the capacitor discharges to VB through the external
resistor RT with a time constant = RT xCT.
Figure 6. CT Attenuator Control Block Circuit
RT
CONTROL
CIRCUIT
60 A
EACH
CT
2.0 k
I2
I1
4
VB
CT
C1 -- C4
TO
ATTENUATORS
VOL. CONTROL
DIAL TONE DET.
AGC
+
--
MICROPHONE AMPLIFIER
The microphone amplifier (Pins 10, 11) has the noninvert-
ing input internally connected to VB, while the inverting input
and the output are pinned out. Unlike most op--amps, the
amplifier has an all--NPN output stage, which maximizes
phase margin and gain--bandwidth. This feature ensures
stability at gains less than unity, as well as with a wide range
of reactive loads. The open loop gain is typically 80 dB
(f < 100 Hz), and the gain--bandwidth is typically 1.0 MHz
(See Figure 16). The maximum p--p output swing is typically
1.0 volt less than VCC with an output impedance of < 10
until current limiting is reached (typically 1.5 mA). Input bias
current at MCI is typically 40 nA out of the pin.
Figure 7. Microphone Amplifier and Mute
RMF
VCC
VB
75 k
MCO
RMI
FROM
MIKE
VCC
75 k
GAIN = –
RMF
RMI
--
+
MCI
The muting function (Pin 12), when activated, will reduce
the gain of the amplifier to ≈-- 39 dB (with RMI = 5.1 k)by
shorting the output to the inverting input (see Figure 7). The
mute input has a threshold of ≈1.5 volts, and the voltage at
this pin must be kept within the range of ground and VCC
should be grounded.
HYBRID AMPLIFIERS
The two hybrid amplifiers (at HTO+, HTO--, and HTI), in
four wire converter for interfacing to the telephone line. The
gain of the first amplifier (HTI to HTO--) is set by external re-
sistors (gain = -- RHF/RHI in Figure 2), and its output drives
the second amplifier, the gain of which is internally set at
-- 1.0. Unlike most op--amps, the amplifiers have an all--NPN
output stage, which maximizes phase margin and gain--
bandwidth. This feature ensures stability at gains less than
unity, as well as with a wide range of reactive loads. The
open loop gain of the first amplifier is typically 80 dB, and the
gain bandwidth of each amplifier is ≈1.0 MHz (see Fig-
ure 16). The maximum p--p output swing of each amplifier is
typically 1.2 volts less than VCC with an output impedance of
<10 until current limiting is reached (typically 8.0 mA). The
output current capability is guaranteed to be a minimum of
5.0 mA. The bias current at HTI is typically 30 nA out of the
pin.
The connections to the coupling transformer are shown in
the Block Diagram (Figure 2). The block labeled ZBal is the
balancing network necessary to match the line impedance.
FILTER
The operation of the filter circuit is determined by the exter-
nal components. The circuit within the MC34118, from pins FI
to FO is a buffer with a high input impedance (> 1.0 M), and
a low output impedance (< 50 ). The configuration of the
external components determines whether the circuit is a
high--pass filter (as shown in Figure 2), a low--pass filter, or a
band--pass filter.
As a high pass filter, with the components shown in Fig-
ure 8, the filter will keep out 60 Hz (and 120 Hz) hum which
can be picked up by the external telephone lines. As a low
pass filter (Figure 9), it can be used to roll off the high end
frequencies in the receive circuit, which aids in protecting
against acoustic feedback problems.
Figure 8. High Pass Filter
R1
56 k
MC34118
260 A
VCC
FO
100 k
FI
C2
C1
R2
220
k
4700 pF
305 Hz
50
fN =
1
2π
1
C2R1R2
FOR C1 = C2
fN
0
-- 3.0
-- 30
VB
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| MC34118-E28-T | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:VOICE SWITCHED SPEAKER-PHONE CIRCUIT |
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| MC34118G-E28-T | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:VOICE SWITCHED SPEAKER-PHONE CIRCUIT |
| MC34118G-S28-R | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:VOICE SWITCHED SPEAKER-PHONE CIRCUIT |
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