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| 型号： | SP211EHET-L/TR |
| 厂商： | Exar Corporation |
| 文件页数： | 15/16页 |
| 文件大小： | 0K |
| 描述： | IC TXRX RS232 MULTI-CH 28SOIC |
| 标准包装： | 1,500 |
| 类型： | 收发器 |
| 驱动器/接收器数： | 4/5 |
| 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： | 28-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 28-SOIC W |
| 包装： | 带卷 (TR) |
Exar Corporation 48720 Kato Road, Fremont CA, 94538 50-668-707 www.exar.com
SP2EH_23EH_0_060
8
Charge–Pump
The charge pump is a
Exar-patenteddesign
(5,306,954) and uses a unique approach
compared to older less-efficient designs.
The charge pumps still requires four external
capacitors, but uses a four-phase voltage
shifting technique to attain symmetrical 0V
power supplies. Figure 3a shows the wave-
form found on the positive side of capacitor
C2, and Figure 3b shows the negative side
of capacitor C2. There is a free-running
oscillator that controls the four phases of
the voltage shifting. A description of each
phaseisasfollows:
+10V
a) C
2
+
gND
b) C
2
–
–10V
Figure 5. Typical waveforms seen on ca-
pacitor C2 when all drivers are at maximum
load.
Phase 1
— V
SS charge storage —During this phase of
theclockcycle,thepositivesideofcapacitors
C
and C2 are initially charged to +5V. C
+
is
then switched to ground and charge on C
–
is
transferred to C
2
–
. Since C
2
+
is connected to
+5V, the voltage potential across capacitor
C
2 is now 0V.
Phase 2
— V
SS transfer — Phase two of the clock con-
nects the negative terminal of C
2 to the VSS
storage capacitor and the positive terminal
of C
2 to ground, and transfers the generated
–l0V to C
3. Simultaneously, the positive side
of capacitor C
is switched to +5V and the
negative side is connected to ground.
Phase 3
— V
DD charge storage — The third phase
of the clock is identical to the first phase
— the charge transferred in C
produces
–5V in the negative terminal of C
, which
is applied to the negative side of capacitor
C
2. Since C2
+
is at +5V, the voltage potential
across C
2 is l0V.
Phase 4
— V
DD transfer — The fourth phase of the
clock connects the negative terminal of C
2
to ground and transfers the generated l0V
across C
2 to C4, the VDD storage capacitor.
Again, simultaneously with this, the positive
side of capacitor C
is switched to +5V and
the negative side is connected to ground,
and the cycle begins again.
Since both V+ and V– are separately gen-
erated from V
CC in a no–load condition, V+
and V– will be symmetrical. Older charge
pump approaches that generate V– from
V+ will show a decrease in the magnitude
of V– compared to V+ due to the inherent
inefficienciesinthedesign.
The clock rate for the charge pump typically
operates at 5kHz. The external capacitors
must be a minimum of 0.F with a 6V
breakdown rating.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP211ET | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:+5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP211ET/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:+5V High-Speed RS-232 Transceivers with 0.1mF Capacitors |
| SP211ET-L | 功能描述:RS-232接口集成电路 5V 4-DRVR/5-RCVR 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: |
| SP211ET-L/TR | 功能描述:RS-232接口集成电路 5V 4-DRVR/5-RCVR 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: |
| SP211H | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:+5V High-Speed RS-232 Transceivers |
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