- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄383995 > TEA1085A (NXP SEMICONDUCTORS) Listening-in circuit for line-powered telephone sets PDF資料下載
參數(shù)資料
| 型號： | TEA1085A |
| 廠商： | NXP SEMICONDUCTORS |
| 元件分類： | 通信及網(wǎng)絡(luò) |
| 英文描述： | Listening-in circuit for line-powered telephone sets |
| 中文描述： | SPECIALTY TELECOM CIRCUIT, PDIP24 |
| 封裝： | 0.600 INCH, PLASTIC, DIP-24 |
| 文件頁數(shù)： | 10/32頁 |
| 文件大?。?/td> | 199K |
| 代理商： | TEA1085A |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁當(dāng)前第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁
March 1992
10
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
Power down input (PD) pin 19
During pulse dialling or register recall (timed loop break)
the telephone line is interrupted, thereby breaking the
supply to the transmission and listening-in circuits. The
capacitor connected to V
BB
provides the supply for the
listening-in circuit during the supply breaks.
By making the PD input HIGH during the loop break the
requirement on the capacitor is eased and, consequently,
the internal (standby) current consumption I
BBO
(Fig.4) at
V
BB
is reduced from 3.8 mA to 400
μ
A typical. So that the
transmission circuit is not affected transistors TR1 and
TR2 are inhibited and the bias current is reduced from
≈
0.4 mA to
≈
55
μ
A with V
SUP
= 4.5 V in the following
equation:
I
SUP(PD)
= I
BIAS(PD)
= (V
SUP
2V
d
) / Ra
(where 4.2 V
<
V
SUP
<
V
BB
+
3 V)
2V
d
= the voltage drop across 2 internal diodes (
≈
1.3 V)
Ra = an internal resistor of typical 60 k
Larsen limiter current stabilizer (SIC) pin 17
A current reference is set by resistor R36 between SIC and
V
SS
. The preferred value is 120 k
. The internal reference
current is given by the following equation:
I
SIC
= 1.25 / R36; when R36 = 120 k
, I
SIC
= 10.5
μ
A
Changing the value of R36 will affect the timing of the
Larsen level limiter system.
Larsen limiter preamplifier (LAI1/LAI2 and QLA) pins
9/10 and 11
This circuit amplifies the microphone signal to a level
suitable for the Larsen limiter detector. The gain is set by
external components (see Fig.8).
Normally the gain is set to the same level as the
microphone amplifier of the transmission circuit, this
ensures that the output signal level at output QLA is equal
to the line signal level.
The gain between QLA and the microphone input is given
by the following equation (the high-pass filter is not taken
into account):
A
pre
= V
QLA
/ V
M
= R29 / R26; in the basic application
R25 = R26 = 10 k
The gain can be adjusted between 30 dB (R29 = 316 k
)
and 52 dB (R29 = 4 M
). The impedance result of R28 and
R27 in parallel must be equal to R29
(e.g. R27 = R28 = 2
×
R29).
Fig.8 Larsen limiter preamplifier and voltage/current converter.
handbook, full pagewidth
MGR037
LAI
+
LAI
+
+
R25
R26
R29
C22
C23
VM
DTI
DCA
IDCA
THL1
THL2
R27
QLA
C24
R30
R33
R32
C25
R31
R35
R34
VQLA
VBB
VSS
VBB
R28
LARSEN
DETECTOR
LLC
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TEA1085AT | Listening-in circuit for line-powered telephone sets |
| TEA1085T | Listening-in circuit for line-powered telephone sets |
| TEA1093 | Hands-free IC |
| TEA1093T | Hands-free IC |
| TEA1094 | Hands free IC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TEA1085AT | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Listening-in circuit for line-powered telephone sets |
| TEA1085T | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Listening-in circuit for line-powered telephone sets |
| TEA1088T | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:SMPS Battery Charger Control Circuit |
| TEA1093 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Hands-free IC |
| TEA1093T | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Hands-free IC |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。