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參數(shù)資料
| 型號： | 4559 |
| 廠商： | Renesas Technology Corp. |
| 英文描述： | SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER |
| 中文描述： | 單芯片4位微機的CMOS |
| 文件頁數(shù)： | 119/148頁 |
| 文件大?。?/td> | 1732K |
| 代理商： | 4559 |
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Rev.1.04
Aug 23, 2007
Page 72 of 146
REJ03B0188-0104
4559 Group
NOTES ON NOISE
Countermeasures against noise are described below.
The following countermeasures are effective against noise in
theory, however, it is necessary not only to take measures as
follows but to evaluate before actual use.
(1) Shortest wiring length
The wiring on a printed circuit board can function as an antenna
which feeds noise into the microcomputer.
The shorter the total wiring length (by mm unit), the less the
possibility of noise insertion into a microcomputer.
(1) Wiring for RESET input pin
Make the length of wiring which is connected to the RESET
input pin as short as possible.
Especially, connect a capacitor across the RESET input pin
and the VSS pin with the shortest possible wiring.
Reason
In order to reset a microcomputer correctly, 1 machine cycle or
more of the width of a pulse input into the RESET pin is
required.
If noise having a shorter pulse width than this is input to the
RESET input pin, the reset is released before the internal state
of the microcomputer is completely initialized.
This may cause a program runaway.
Fig 74. Wiring for the RESET input pin
(2) Wiring for clock input/output pins
Make the length of wiring which is connected to clock I/O
pins as short as possible.
Make the length of wiring across the grounding lead of a
capacitor which is connected to an oscillator and the VSS
pin of a microcomputer as short as possible.
Separate the VSS pattern only for oscillation from other
VSS patterns.
Fig 75. Wiring for clock I/O pins
Reason
If noise enters clock I/O pins, clock waveforms may be
deformed. This may cause a program failure or program
runaway.
Also, if a potential difference is caused by the noise between
the VSS level of a microcomputer and the VSS level of an
oscillator, the correct clock will not be inpu t in the
microcomputer.
(3) Wiring to CNVSS pin
Connect an approximately 5 k
resistor to the VPP pin and
also to the GND pattern supplied to the VSS pin with
shortest possible wiring.
Reason
The CNVSS pin is the power source input pin for the built-in
QzROM. When programming in the built-in QzROM, the
impedance of the CNVSS pin is low to allow the electric
current for writing flow into the QzROM. Because of this,
noise can enter easily. If noise enters the CNVSS pin, abnormal
instruction codes or data are read from the built-in QzROM,
which may cause a program runaway.
Fig 76. Wiring for CNVSS pin
RESET
Reset
circuit
Noise
VSS
N.G.
Reset
circuit
VSS
RESET
VSS
O.K.
Noise
XIN
XOUT
VSS
N.G.
XIN
XOUT
VSS
O.K.
CN V s s
V SS
T h e shorte st
about 5k
N ote : T h is indica te s pin.
(Note)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| 456700000 | Terminal Block; Leaded Process Compatible:Yes |
| 457000000 | Cross Connector; Number of Positions:10; Current Rating:24 VA |
| 45714-0003 | Edge Connector,PCB Mnt,RECEPT,8 Contacts,0.507 Pitch,COMPLIANT FIT Terminal,GUIDE SLOT |
| 45714-0001 | Card Edge Connector; No. of Contacts:4; Pitch Spacing:0.508"; Contact Termination:Press-Fit; Body Material:LCP Liquid Crystal Polymer, Glass-filled; Mounting Type:Through Hole; Series:45714; Color:Black; Voltage Rating:250V RoHS Compliant: Yes |
| 45714-0002 | Card Edge Connector; No. of Contacts:6; Pitch Spacing:0.508"; Contact Termination:Press-Fit; Body Material:LCP Liquid Crystal Polymer, Glass-filled; Mounting Type:Through Hole; Series:45714; Color:Black; Voltage Rating:250V RoHS Compliant: Yes |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 4559_08 | 制造商:RENESAS 制造商全稱:Renesas Technology Corp 功能描述:Standard Characteristics |
| 45-590 | 制造商:GC Electronics 功能描述:Conn D-Subminiature Adapter F/F 9/15 POS ST 1 Port |
| 45-590 4/PK | 功能描述:電纜組件 DB-9F DB-15F HI DEN RoHS:否 制造商:Molex 產(chǎn)品:Power Assemblies 類型:Cable Assembly 連接器端口 A:No Connector 連接器端口 A 管腳計數(shù):4 連接器端口 B:No Connector 連接器端口 B 管腳計數(shù): 型式:Male 線規(guī) - 美國線規(guī)（AWG）:20, 28 長度:0.305 m 顏色:Black, Red |
| 4-5-5906 | 功能描述:TAPE 5906 VHB FOAM 4" X 5YD 制造商:3m (tc) 系列:* 零件狀態(tài):有效 標(biāo)準(zhǔn)包裝:1 |
| 4-5-5907 | 功能描述:TAPE 5907 VHB FOAM 4" X 5YD 制造商:3m (tc) 系列:* 零件狀態(tài):有效 標(biāo)準(zhǔn)包裝:1 |
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