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參數(shù)資料
| 型號(hào)： | SP3238EEEA |
| 元件分類： | RS-232 |
| 英文描述： | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| 中文描述： | 5V的高速RS - 232收發(fā)器與0.1uF電容 |
| 文件頁數(shù)： | 10/20頁 |
| 文件大?。?/td> | 248K |
| 代理商： | SP3238EEEA |
Date: 02/24/05
SP3238EE Intelligent +3.0V to +5.5V RS-232 Transceiver
Copyright 2005 Sipex Corporation
10
noisy transmission lines. Should an input be left
unconnected, an internal 5k
pulldown resistor
to ground will commit the output of the receiver
to a HIGH state.
Charge Pump
The charge pump is a Sipex–patented design
(U.S. #5,306,954) and uses a unique approach
compared to older less–efficient designs. The
charge pump still requires four external
capacitors, but uses a four–phase voltage
shifting technique to attain symmetrical 5.5V
power supplies. The internal power supply
consists of a regulated dual charge pump that
provides output voltages 5.5V regardless of the
input voltage (V
CC
) over the +3.0V to +5.5V
range. This is important to maintain compliant
RS-232 levels regardless of power supply
fluctuations.
The charge pump operates in a discontinuous
mode using an internal oscillator. If the output
voltages are less than a magnitude of 5.5V, the
charge pump is enabled. If the output voltages
exceed a magnitude of 5.5V, the charge pump is
disabled. This oscillator controls the four phases
of the voltage shifting (Figure 13). A descrip-
tion of each phase follows.
Phase 1
(Figure 11)
— V
SS
charge storage — During this phase of
the clock cycle, the positive side of capacitors
C
1
and C
2
are initially charged to V
CC
. C
l+
is
then switched to GND and the charge in C
1–
is
transferred to C
2–
. Since C
2+
is connected to
V
CC
, the voltage potential across capacitor C
2
is
now 2 times V
CC
.
Phase 2
(Figure 12)
— V
SS
transfer — Phase two of the clock
connects the negative terminal of C
2
to the V
SS
storage capacitor and the positive terminal of C
2
to GND. This transfers a negative generated
voltage to C
3
. This generated voltage is
regulated to a minimum voltage of -5.5V.
Simultaneous with the transfer of the voltage to
C
3
, the positive side of capacitor C
1
is switched
to V
CC
and the negative side is connected to
GND.
Phase 3
(Figure 14)
— V
DD
charge storage — The third phase of the
clock is identical to the first phase — the charge
transferred in C
1
produces –V
CC
in the negative
terminal of C
1
, which is applied to the negative
side of capacitor C
2
. Since C
2+
is at V
CC
, the
voltage potential across C
2
is 2 times V
CC
.
Phase 4
(Figure 15)
— V
DD
transfer — The fourth phase of the clock
connects the negative terminal of C
2
to GND,
and transfers this positive generated voltage
across C
2
to C
4
, the V
DD
storage capacitor. This
voltage is regulated to +5.5V. At this voltage,
the internal oscillator is disabled. Simultaneous
with the transfer of the voltage to C
4
, the
positive side of capacitor C
1
is switched to V
CC
and the negative side is connected to GND,
allowing the charge pump cycle to begin again.
The charge pump cycle will continue as long as
the operational conditions for the internal
oscillator are present.
Since both V
+
and V
–
are separately generated
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 inefficiencies in the design.
The clock rate for the charge pump typically
operates at 500kHz. The external capacitors can
be as low as 0.1
μ
F with a 16V breakdown
voltage rating.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP3238EEEY | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP3238EECA | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP3238EECA-L | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP3238EECY | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP3238EECY-L | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP3238EEEA/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Intelligent +3.0V to +5.5V RS-232 Transceiver |
| SP3238EEEA-L | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Intelligent +3.0V to +5.5V RS-232 Transceiver |
| SP3238EEEA-L/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Intelligent +3.0V to +5.5V RS-232 Transceiver |
| SP3238EEEY | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Intelligent +3.0V to +5.5V RS-232 Transceiver |
| SP3238EEEY/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Intelligent +3.0V to +5.5V RS-232 Transceiver |
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