- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄384435 > HM9270D (ELAN Microelctronics Corp .) DTMF RECEIVER PDF資料下載
參數(shù)資料
| 型號： | HM9270D |
| 廠商： | ELAN Microelctronics Corp . |
| 英文描述： | DTMF RECEIVER |
| 中文描述： | 雙音多頻接收器 |
| 文件頁數(shù)： | 8/10頁 |
| 文件大?。?/td> | 66K |
| 代理商： | HM9270D |
DTMF RECEIVER
HM 9270C/D
- 8 -
C
V
C
R
V
DD
V
DD
St/GT
ESt
S
tD
V
DD
V
TST
t
GTP
GTA
t
=(RC) ln (
V
V
DD
=(RC) ln (
V
DD
-
)
)
TST
0.1
μ
f
V
DD
S
t
GT
/
ES
t
C
R2
R1
V
DD
S
t
GT
/
ES
t
C
R2
R1
FIGURE 7. BASIC STEERING CIRCUIT
Guard Time Adjustment
In many situations not requiring independent selection of receive and pause, the simple steering circuit of Fig. 7 is
applicable. Component values are chosen according to the following formulae:
t
= t
+ t
t
= t
+ t
The value of t
is a parameter of the device (see table) and t
is the minimum signal duration to be recognized by
the receiver. A value for C of 0.1 μF is recommended for most applications, leaving R to be selected by the
designer. For example, a suitable value of R for a t
of 40mS would be 300k.
Different steering arrangements may be used to select independently the guard-times for tone-present (t
) and
tone-absent (t
). This may be necessary to meet system specifications which place both accept and reject limits on
both tone duration and interdigital pause.
Guard-time adjustment also allows the designer to tailor system parameters such as talk off and noise immunity.
Increasing t
improves talk-off performance, since it reduces the probability that tones simulated by speech will
maintain signal condition for long enough to be registered. On the other hand, a relatively short t
with a long t
DO
would be appropriate for extremely noisy environments where fast acquisition time and immunity to drop - outs
would be required. Design information for guard-time adjustment is shown in Fig. 8.
tGTP=(Rp C) In (
tGTP=(Rp C) In (
tGTA=(R1 C) In (
R1R2
Rp=
tGTA=(R1 C) In (
Rp=
V
DD
- V
TST
V
DD
V
DD
V
DD
- V
TST
V
DD
V
DD
)
V
TST
)
)
V
TST
)
R1+R2
R1R2
R1+R2
a) Decreasing t
GTP
(t
GTP
< t
GTA
)
b) Decreasing t
GTP
(t
GTP
> t
GTA
)
FIGURE 8. GUARD TIME ADJUSTMENT
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| HMA2701R1 | FULL PITCH MINI-FLAT PACKAGE 4-PIN OPTOCOUPLERS |
| HMA121AR2V | FULL PITCH MINI-FLAT PACKAGE 4-PIN OPTOCOUPLERS |
| HMAA2705R4V | FULL PITCH MINI-FLAT PACKAGE 4-PIN OPTOCOUPLERS |
| HMAA2705V | FULL PITCH MINI-FLAT PACKAGE 4-PIN OPTOCOUPLERS |
| HMAA2705R1 | Circular Connector; Body Material:Aluminum; Series:PT06; Number of Contacts:3; Connector Shell Size:12; Connecting Termination:Solder; Circular Shell Style:Straight Plug; Circular Contact Gender:Socket; Insert Arrangement:12-3 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| HM92M | 制造商:HSMC 制造商全稱:HSMC 功能描述:PNP EPITAXIAL PLANAR TRANSISTOR |
| HM94 | 制造商:HSMC 制造商全稱:HSMC 功能描述:PNP EPITAXIAL PLANAR TRANSISTOR |
| HM965 | 制造商:HSMC 制造商全稱:HSMC 功能描述:NPN EPITAXIAL PLANAR TRANSISTOR |
| HM9-6516BB6129 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| HM9-6516BD6129 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。