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參數(shù)資料
| 型號(hào)： | SP3222CY |
| 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)： | 10/19頁 |
| 文件大小： | 138K |
| 代理商： | SP3222CY |
Date: 06/22/04 SP3222EH/3232EH 3.3V, 460 Kbps RS-232 Transceivers
Copyright 2004 Sipex Corporation
10
Receivers
The receivers convert EIA/TIA-232 levels to
TTL or CMOS logic output levels. The
SP3222EH receivers have an inverting tri-state
output.Receiver outputs (RxOUT) are tri-stated
when the enable control EN = HIGH. In the
shutdown mode, the receivers can be active or
inactive. EN has no effect on TxOUT. The truth
table logic of the
SP3222EH
driver and receiver
outputs can be found in
Table 2
.
Since receiver input is usually from a transmis-
sion line where long cable lengths and system
interference can degrade the signal and inject
noise, the inputs have a typical hysteresis margin
of 300mV. Should an input be left unconnected,
a 5k
pulldown resistor to ground forces the
output of the receiver HIGH.
Charge Pump
The
Sipex
patented charge pump (5,306,954)
uses a four–phase voltage shifting technique to
attain symmetrical 5.5V power supplies and
requires four external capacitors. The internal
power supply consists of a regulated dual charge
pump that provides an output voltage of 5.5V
regardless of the input voltage (V
CC
) over the
+3.0V to +5.5V range.
In most circumstances, decoupling the power
supply can be achieved adequately using a
0.1
μ
F bypass capacitor at C5 (refer to
Figures 6
and
7
). In applications that are sensitive to
power-supply noise,V
and ground can be
decoupled with a capacitor of the same value
as charge-pump capacitor C1. It is always
important to physically locate bypass capacitors
close to the IC.
The charge pump operates in a discontinuous
mode using an internal oscillator. If the output
voltage is less than 5.5V, the charge pump is
enabled. If the output voltage exceeds 5.5V,
the charge pump is disabled. An oscillator
controls the four phases of the voltage shifting.
A description of each phase follows.
Phase 1: V
Charge Storage
(Figure 12)
During this phase of the clock cycle, the positive
side of capacitors C
and C
are charged to V
.
C
l
C
to V
, the voltage potential across capacitor C
2
is now 2 times V
CC
.
+
is then switched to GND and the charge in
–
is transferred to C
–
. Since C
+
is connected
Phase 2: V
Transfer
(Figure 13)
Phase two of the clock connects the negative
terminal of C
to the V
storage capacitor and
the positive terminal of C
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
, the positive side
of capacitor C
is switched to V
CC
and the
negative side is connected to GND.
Phase 3: V
Charge Storage
(Figure 15)
The third phase of the clock is identical to the
first phase — the charge transferred in C
1
produces –V
in the negative terminal of C
1
,
which is applied to the negative side of capacitor
C
. Since C
across C
2
is 2 times V
CC
.
+
is at V
CC
, the voltage potential
Table 2. Truth Table Logic for Shutdown and Enable
Control
N
D
H
S
N
E
T
U
O
x
T
T
U
O
x
R
0
0
e
T
e
v
A
0
1
e
T
e
T
1
0
e
v
A
e
v
A
1
1
e
v
A
e
T
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP3222E | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP3222EET | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP3222EEY | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP3222EH | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| SP3222EHCT | 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 |
|---|---|
| SP3222E | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:The SP3222E/3232E series is an RS-232 transceiver solution intended for portable or handheld applications such as notebook or palmtop computers. |
| SP3222EA | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:True +3.0V to +5.5V RS-232 Transceivers |
| SP3222EB | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:CorporationTrue +3.0V to +5.5V RS-232 Transceivers |
| SP3222EB_0511 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:CorporationTrue +3.0V to +5.5V RS-232 Transceivers |
| SP3222EBCA | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:CorporationTrue +3.0V to +5.5V RS-232 Transceivers |
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