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| 型号： | SP207EET-L/TR |
| 厂商： | Exar Corporation |
| 文件页数： | 16/19页 |
| 文件大小： | 0K |
| 描述： | IC TXRX RS232 ESD LP 24SOIC |
| 标准包装： | 1,500 |
| 类型： | 收发器 |
| 驱动器/接收器数： | 5/3 |
| 规程： | RS232 |
| 电源电压： | 4.5 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 24-SOIC W |
| 包装： | 带卷 (TR) |
Exar Corporation 48720 Kato Road, Fremont CA, 94538 50-668-707 www.exar.com
SP207E_0_052
6
Receiver input thresholds are between .2
to .7 volts typical. This allows the receiver
todetectstandardTTLorCMOSlogic-level
signals as well as RS-232 signals. If a re-
ceiver input is left unconnected or un-driven,
a5kpulldownresistortogroundwillcommit
the receiver to a logic- output state.
Highly Efficient Charge–Pump
The onboard dual-output charge pump is
usedtogeneratepositiveandnegativesignal
voltagesfortheRS-232drivers. Thisenables
fullycompliantRS-232andV.28signalsfrom
a single power supply device.
The charge pumps use four external capaci-
tors to hold and transfer electrical charge.
The
Exar design uses a unique approach
comparedtoolder,less–efficientdesigns.
The pumps use a four–phase voltage shift-
ing technique to attain symmetrical V+ and
V- power supplies. An intelligent control
oscillator regulates the operation of the
chargepumptomaintainthepropervoltages
atmaximumefficiency.
Phase 1
V
SS charge store and double — The positive
terminalsofcapacitorsC
and C2 are charged
from V
CC with their negative terminals initially
connected to ground. C
l+ is then connected
to ground and the stored charge from C
– is
superimposed onto C
2
–. Since C
2+ is still
connectedtoV
CC the voltage potential across
capacitor C
2 is now 2 x VCC.
VCC = +5V
–5V
+5V
VSS Storage Capacitor
VDD Storage Capacitor
C1
C2
C3
C4
+
–
Phase 2
— V
SS transfer and invert — Phase two con-
nects the negative terminal of C
2 to the VSS
storage capacitor and the positive terminal
of C
2 to ground. This transfers the doubled
andinverted(V-)voltageontoC
3. Meanwhile,
capacitor C
charged from VCC to prepare it
for its next phase.
Phase 3
V
DD charge store and double —Phase three
isidenticaltothefirstphase.Thepositive
terminalsofcapacitorsC
and C2 are charged
from V
CC with their negative terminals initially
connected to ground. C
l+ is then connected
to ground and the stored charge from C
– is
superimposed onto C
2–. Since C2+ is still
connectedtoV
CC the voltage potential across
capacitor C
2 is now 2 x VCC.
Phase 4
V
DD transfer — The fourth phase connects
the negative terminal of C
2 to ground and
the positive terminal of C
2 to the VDD stor-
age capacitor. This transfers the doubled
(V+)voltageontoC
4. Meanwhile, capacitor
C
is charged from VCC to prepare it for its
next phase.
Figure . Charge Pump — Phase
VCC = +5V
VSS Storage Capacitor
VDD Storage Capacitor
C1
C2
C3
C4
+
–
-7V
Figure 2. Charge Pump — Phase 2
VCC = +5V
–5V
+5V
VSS Storage Capacitor
VDD Storage Capacitor
C1
C2
C3
C4
+
–
Figure 3. Charge Pump — Phase 3
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP207EET-TR | 制造商:Exar Corporation 功能描述: |
| SP207EH | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High Speed +5V High Performance RS232 Transceivers |
| SP207EHCA | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High Speed +5V High Performance RS232 Transceivers |
| SP207EHCA-L | 制造商:Exar Corporation 功能描述:TRANSCEIVER RS-232 HI SPEED 207 |
| SP207EHCP | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High Speed +5V High Performance RS232 Transceivers |
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