- 您現在的位置：買賣IC網 > PDF目錄382703 > U4084B Low-Voltage, Voice-Switched Circuit for Hands-Free Operation PDF資料下載
參數資料
| 型號： | U4084B |
| 英文描述： | Low-Voltage, Voice-Switched Circuit for Hands-Free Operation |
| 中文描述： | 低電壓，語音開關電路免提操作 |
| 文件頁數： | 17/26頁 |
| 文件大小： | 544K |
| 代理商： | U4084B |
U4084B
Preliminary Information
TELEFUNKEN Semiconductors
Rev. A1, 31-Jan-97
17 (26)
Design Hints
Switching Time, Figure 6
The switching time of the U4084B circuit is determined
by C
T
(Pin 11, refer to figure 6), and the capacitors at the
level-detector outputs (RLO1, RLO2, TLO1, TLO2), see
figure 2.
The switching time from idle to receive or transmit mode
is determined by the capacitor at C
T
, together with the
internal current sources. The switching time is:
T
V
C
T
I
240
5
60
20.0 ms
where:
V
=
=
=
240 mV
5 F
60 A
C
T
I
If the circuit switches directly from receive to transmit
mode (or vice-versa), the total switching time is 40 ms.
The switching time depends on the mode selection. If the
circuit is switching to “fast idle”, the time constant is
determined by the C
T
capacitor, and the internal 2.0-k
resistor. With C
T
= 5.0
approximately 10 ms, resulting in a switching time of
approximately 30 ms (for 95% change). Fast idle is mode
may occur if both persons are talking at the same time,
thus trying to get control of the circuit. The switching
time from idle back to either transmit or receive mode is
described above.
F, the time constant is
By switching to “slow idle”, the time constant is
determined by the C
T
capacitor and R
T
, the external
resistor (see figure 6). With C
T
= 5.0 F, and R
T
= 120 k ,
the time constant is approximately 600 ms, resulting a
switching time of approximately 1.8 seconds (for 95%
change). The switching to slow idle starts when both
speakers have stopped talking. The switching time back
to the original mode depends on how fast that person
starts talking again. The sooner the speaking starts during
the 1.8-second period, the faster the switching time since
a smaller voltage excursion is required. The switching
time is determined by the internal current source as
described above.
The above switching times occur after the level detectors
have detected the appropriate signal levels, since their
outputs operate the attenuator control block. The rise time
of the level detectors’ outputs to new speech is quick by
comparison (approximately 1.0 ms), determined by the
internal 350
resistor and the external capacitor
(typically 2.0 F). The output’s decay time is determined
by the external capacitor, and an internal 4.0- A current
source giving a decay rate of 60 ms for a 120 mV
excursion at RLO or TLO. The total response time of the
circuit is not constant as it depends on the relative strength
of the signals at the different level detectors and the
timing of the signals with respect to each other. The
capacitors at the four outputs (RLO1, RLO2, TLO1,
TLO2) must have equal values (
problems in timing and level response.
10%) to prevent
The rise time of the level detector’s outputs is too short
to be of significant. The decay time, however provides a
significant part of the “hold time” necessary to hold the
circuit during the normal pauses in speech.
The components at the inputs of the level detectors (RLI1,
RLI2, TLI1, TLI2) do not affect the switching time but
rather affect the relative signal levels required to switch
the circuit and the frequency response of the detectors.
Design Equations
Following definitions are used @ 1.0 kHz with reference
to figures 2 and 21 whereas coupling capacitors are
omitted for the sake of simplicity:
–
G
MA
is the gain of the microphone amplifier
measured from the microphone output to TI
(typically 35 V/V, or 31 dB);
–
G
T
is the gain of the transmit attenuator,
measured from TI to TO;
–
G
EXT
is the gain of an external transmit amplifier
(typically 10.2 V/V, or 20.1 dB)
–
G
ST
is the side-tone gain;
–
G
EXR
is the gain of an external receive amplifier;
–
G
R
is the gain of the receive attenuator measured
from RI to RECO;
–
G
SA
is the gain of the speaker amplifier, mea-
sured from RECO to the differential output of the
speaker amplifier (typically 22 V/V or 26.8 dB);
–
G
AC
is the acoustic coupling, measured from the
speaker differential voltage to the microphone
output voltage.
相關PDF資料 |
PDF描述 |
|---|---|
| U4087B | Low Voltage Voice Switch Interface Circuit for Hands-free Operation in Telephone |
| U4087B-FP | Low Voltage Voice Switch Interface Circuit for Hands-free Operation in Telephone |
| U4090B-N | Low power dual voltage comparators |
| U4090B-NFN | Low power dual voltage comparators |
| U4090B-NFNG3 | Low power dual voltage comparators |
相關代理商/技術參數 |
參數描述 |
|---|---|
| U4084B-FL | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Speakerphone Circuit |
| U4085B | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Technische Daten Technical Data |
| U4087B | 制造商:TEMIC 制造商全稱:TEMIC Semiconductors 功能描述:Low Voltage Voice Switch Interface Circuit for Hands-free Operation in Telephone |
| U4087B-FP | 制造商:TEMIC 制造商全稱:TEMIC Semiconductors 功能描述:Low Voltage Voice Switch Interface Circuit for Hands-free Operation in Telephone |
| U4089B | 制造商:ATMEL 制造商全稱:ATMEL Corporation 功能描述:MONOLITHIC INTEGRATED FEATUREPHONE CIRCUIT |
發布緊急采購，3分鐘左右您將得到回復。