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參數(shù)資料
| 型號： | SN74LS122N |
| 廠商： | MOTOROLA INC |
| 元件分類： | 諧振器 |
| 英文描述： | RETRIGGERABLE MONOSTABLE MULTIVIBRATORS |
| 中文描述： | LS SERIES, MONOSTABLE MULTIVIBRATOR, PDIP16 |
| 封裝： | PLASTIC, 648-08, 16 PIN |
| 文件頁數(shù)： | 2/10頁 |
| 文件大?。?/td> | 278K |
| 代理商： | SN74LS122N |
5-198
FAST AND LS TTL DATA
SN54/74LS122
SN54/74LS123
LS122
FUNCTIONAL TABLE
INPUTS
OUTPUTS
CLEAR
A1
A2
B1
B2
Q
Q
L
X
X
X
H
H
H
H
H
H
H
↑
↑
X
H
X
X
L
L
X
X
H
↓
↓
L
X
X
H
X
X
X
X
L
L
↓
↓
H
X
L
X
X
L
X
↑
H
↑
H
H
H
H
H
H
X
X
X
L
H
↑
H
↑
H
H
H
H
H
L
L
L
L
H
H
H
H
LS123
FUNCTIONAL TABLE
INPUTS
OUTPUTS
CLEAR
A
B
Q
Q
L
X
X
H
H
↑
X
H
X
L
↓
L
X
X
L
↑
H
H
L
L
L
H
H
H
TYPICAL APPLICATION DATA
The output pulse tW is a function of the external compo-
nents, Cext and Rext or Cext and Rint on the LS122. For values
of Cext
≥
1000 pF, the output pulse at VCC = 5.0 V and VRC =
5.0 V (see Figures 1, 2, and 3) is given by
tW = K Rext Cext where K is nominally 0.45
If Cext is on pF and Rext is in k
then tW is in nanoseconds.
The Cext terminal of the LS122 and LS123 is an internal
connection to ground, however for the best system perfor-
mance Cext should be hard-wired to ground.
Care should be taken to keep Rext and Cext as close to the
monostable as possible with a minimum amount of inductance
between the Rext/Cext junction and the Rext/Cext pin. Good
groundplane and adequate bypassing should be designed
into the system for optimum performance to insure that no
false triggering occurs.
It should be noted that the Cext pin is internally connected
to ground on the LS122 and LS123, but not on the LS221.
Therefore, if Cext is hard-wired externally to ground, substitu-
tion of a LS221 onto a LS123 socket will cause the LS221 to
become non-functional.
The switching diode is not needed for electrolytic capaci-
tance application and should not be used on the LS122 and
LS123.
To find the value of K for Cext
≥
1000 pF, refer to Figure 4.
Variations on VCC or VRC can cause the value of K to change,
as can the temperature of the LS123, LS122. Figures 5 and
6 show the behavior of the circuit shown in Figures 1 and 2 if
separate power supplies are used for VCC and VRC. If VCC is
tied to VRC, Figure 7 shows how K will vary with VCC and
temperature. Remember, the changes in Rext and Cext with
temperature are not calculated and included in the graph.
As long as Cext
≥
1000 pF and 5K
≤
Rext
≤
260K
(SN74LS122/123) or 5K
≤
Rext
≤
160 K (SN54LS122/123),
the change in K with respect to Rext is negligible.
If Cext
≤
1000 pF the graph shown on Figure 8 can be used
to determine the output pulse width. Figure 9 shows how K will
change for Cext
≤
1000 pF f VCC and VRC are connected to the
same power supply. The pulse width tW in nanoseconds is
approximated by
tW = 6 + 0.05 Cext (pF) + 0.45 Rext (k
) Cext + 11.6 Rext
In order to trim the output pulse width, it is necessary to
include a variable resistor between VCC and the Rext/Cext pin
or between VCC and the Rext pin of the LS122. Figure 10, 11,
and 12 show how this can be done. Rext remote should be kept
as close to the monostable as possible.
Retriggering of the part, as shown in Figure 3, must not
occur before Cext is discharged or the retrigger pulse will not
have any effect. The discharge time of Cext in nanoseconds is
guaranteed to be less than 0.22 Cext (pF) and is typically 0.05
Cext (pF).
For the smallest possible deviation in output pulse widths
from various devices, it is suggested that Cext be kept
≥
1000 pF.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SN74LS122N | 制造商:Texas Instruments 功能描述:Logic - Multivibrator IC |
| SN74LS122N3 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| SN74LS122NE4 | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Retriggerable mono multivibrator RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
| SN74LS122NS | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| SN74LS122NSR | 功能描述:單穩(wěn)態(tài)多諧振蕩器 Retriggerable Mono RoHS:否 制造商:Texas Instruments 每芯片元件:1 邏輯系列:LVC 邏輯類型:Monostable Multivibrator 封裝 / 箱體:SSOP-8 傳播延遲時間:18.6 ns 高電平輸出電流:- 32 mA 低電平輸出電流:32 mA 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
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