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參數(shù)資料
| 型號： | MC145408 |
| 廠商： | Motorola, Inc. |
| 英文描述： | Driver/ Receiver(驅(qū)動器/接收器) |
| 中文描述： | 驅(qū)動器/接收器（驅(qū)動器/接收器） |
| 文件頁數(shù)： | 6/9頁 |
| 文件大?。?/td> | 184K |
| 代理商： | MC145408 |
MC145403
MC145404
MC145405
MC145408
6
MOTOROLA
DI1 – DIn
Data Input Pins
These are the high impedance digital input pins to the driv-
ers. Input voltage levels on these pins are LSTTL compatible
and must be between VCC and GND. A weak pull–up on
each input sets all unused DI pins to VCC, causing the corre-
sponding unused driver outputs to be at VSS.
Tx1 – TXn
Transmit Data Output Pins
These are the EIA–232–E transmit signal output pins,
which swing from VDD to VSS. A logic 1 at the DI input causes
the corresponding Tx output to swing to VSS. A logic 0 at the
DI input causes the corresponding Tx out to swing to VDD.
The actual levels and slew rate achieved will depend on the
output loading (RL
CL).
APPLICATION INFORMATION
POWER SUPPLY CONSIDERATIONS
Figure 4 shows a technique to guard against excessive de-
vice current.
The diode D1 prevents excessive current from flowing
through an internal diode from the VCC pin to the VDD pin
when VDD < VCC by approximately 0.6 V or greater. This high
current condition can exist for a short period of time during
power up/down. Additionally, if the + 12 V supply is switched
off while the + 5 V is on and the off supply is a low impedance
to ground, the diode D1 will prevent current flow through the
internal diode.
The diode D2 is used as a voltage clamp, to prevent VSS
from drifting positive to VCC, in the event that power is re-
moved from VSS (Pin 12). If VSS power is removed, and the
impedance from the VSS pin to ground is greater than
approximately 3 k
, this pin will be pulled to VCC by internal
circuitry causing excessive current in the VCC pin.
If by design, neither of the above conditions are allowed to
exist, then the diodes D1 and D2 are not required.
ESD PROTECTION
ESD protection on IC devices that have their pins accessi-
ble to the outside world is essential. High static voltages ap-
plied to the pins when someone touches them either directly
or indirectly can cause damage to gate oxides and transistor
junctions by coupling a portion of the energy from the I/O pin
to the power supply buses of the IC. This coupling will usually
occur through the internal ESD protection diodes. The key to
protecting the IC is to shunt as much of the energy to ground
as possible before it enters the IC. Figure 4 shows a tech-
nique which will clamp the ESD voltage at approximately
±
15 V using the MMBZ15VDLT1. Any residual voltage which
appears on the supply pins is shunted to ground through the
capacitors C1 – C3. This scheme has provided protection to
the interface part up to
±
10 kV, using the human body model
test.
R
R
R
R
R
VDD
Rx1
Tx1
Rx2
Tx2
Rx3
Tx3
Rx4
Tx4
Rx5
1
2
3
4
5
6
7
8
9
10
DI1
DO2
DI2
DO3
DI3
DO4
DI4
DO5
DI5
GND
22
21
20
19
18
17
16
15
14
13
24
23
11
12
VCC
DO1
VSS
Tx5
+ 5 V
C2
D1
C3
– 12 V
1N5818
1N4001
D2
C1
+ 12 V
1N4001
D
D
D
D
D
Figure 4.
MMBZ15VDLT1 x 10
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| MC145408DWR2 | 制造商:Freescale Semiconductor 功能描述:CMOS DRIVER/RECEIVER, 5 X 5 |
| MC145412P | 制造商:Motorola Inc 功能描述: |
| MC14541BCP | 功能描述:計(jì)時器和支持產(chǎn)品 LOG CMOS OSILATR TIMER RoHS:否 制造商:Micrel 類型:Standard 封裝 / 箱體:SOT-23 內(nèi)部定時器數(shù)量:1 電源電壓-最大:18 V 電源電壓-最小:2.7 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 |
| MC14541BCPG | 功能描述:計(jì)時器和支持產(chǎn)品 3-18V with Auto RoHS:否 制造商:Micrel 類型:Standard 封裝 / 箱體:SOT-23 內(nèi)部定時器數(shù)量:1 電源電壓-最大:18 V 電源電壓-最小:2.7 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 |
| MC14541BD | 功能描述:計(jì)時器和支持產(chǎn)品 LOG CMOS OSILATR TIMER RoHS:否 制造商:Micrel 類型:Standard 封裝 / 箱體:SOT-23 內(nèi)部定時器數(shù)量:1 電源電壓-最大:18 V 電源電壓-最小:2.7 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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