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| 型号： | SP207EET-L |
| 厂商： | Exar Corporation |
| 文件页数： | 17/19页 |
| 文件大小： | 0K |
| 描述： | IC TXRX RS232 ESD LP 24SOIC |
| 标准包装： | 31 |
| 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： | 管件 |
7
Exar Corporation 48720 Kato Road, Fremont CA, 94538 50-668-707 www.exar.com
SP207E_0_052
The Exar charge-pump generates V+ and V-
independently from V
CC. Hence in a no–load
condition V+ and V- will be symmetrical.
Older charge pump approaches generate
V+ and then use part of that stored charge
to generate V-. Because of inherent losses,
the magnitude of V- will be smaller than V+
on these older designs.
Underlightlyloadedconditionstheintelligent
pump oscillator maximizes efficiency by
running only as needed to maintain V+ and
V-. Since interface transceivers often spend
muchoftheirtimeatidle,thispower-efficient
innovation can greatly reduce total power
consumption. This improvement is made
possiblebytheindependentphasesequence
of the Exar charge-pump design.
The clock rate for the charge pump typically
operates at greater than 15kHz, allowing
thepumptorunefficientlywithsmall0.1F
capacitors.Efficientoperationdependson
rapidly charging and discharging C
and
C
2, therefore capacitors should be mounted
closetotheICandhavelowESR(equivalent
seriesresistance).Lowcostsurfacemount
ceramiccapacitors(suchasarewidelyused
forpower-supplydecoupling)areidealfor
use on the charge pump.
However the charge pumps are designed
to be able to function properly with a wide
range of capacitor styles and values. If
polarizedcapacitorsareused,thepositive
and negative terminals should be connected
as shown.
Figure 4. Charge Pump — Phase 4
VCC = +5V
+10V
VSS Storage Capacitor
VDD Storage Capacitor
C1
C2
C3
C4
+
–
+7V
Voltage potential across any of the capaci-
tors will never exceed 2 x V
CC. Therefore
capacitors with working v
oltages as low as
0V rating may be used with a nominal V
CC
supply. C
will never see a potential greater
than V
CC , so a working voltage of 6.3V is
adequate. The reference terminal of the
V
DD capacitor may be connected either to
V
CC or ground, but if connected to ground a
minimum 6V working voltage is required.
Higherworkingvoltagesand/orcapacitance
values may be advised if operating at higher
V
CC or to provide greater stability as the
capacitors age.
+7V
a) C
2
+
gND
b) C
2
–
–7V
Figure 5. Typical waveforms seen on ca-
pacitor C2 when all drivers are at maximum
load.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP207EET-L/TR | 功能描述:RS-232接口集成电路 +/-15KV 5DRVR/3RCVR RS-232 -40-85C RoHS:否 制造商:Exar 数据速率:52 Mbps 工作电源电压:5 V 电源电流:300 mA 工作温度范围:- 40 C to + 85 C 安装风格:SMD/SMT 封装 / 箱体:LQFP-100 封装: |
| 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 |
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