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PDF SP3224E Data sheet ( Hoja de datos )
| Número de pieza | SP3224E | |
| Descripción | 3.0V to 5.5V RS-232 Transceivers | |
| Fabricantes | Exar | |
| Logotipo |  |
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SP3224E-SP3227E
3.0V to 5.5V RS-232 Transceivers with Auto On-Line® Plus
FEATURES
■ 15kV ESD protected RS-232 I/O pins
■ Auto On-line® Plus automatic power saving mode
■ Meets true EIA/TIA-232-F standards from +3.0V to
+5.5V power supply.
■ Adheres to EIA/TIA-562 for interoperability with
EIA/TIA-232 down to a +2.7V supply voltage
■ Regulated charge pump yields stable
RS-232 outputs
■ Drop-in replacement to MAX3224, ICL3224,
MAX3225, ICL3225, MAX3226, ICL3226,
MAX3227 and ICL3227
■ SP3224E and SP3226E reduced EMI with a slew
rate controlled 250kbps data rate
READY 1
C1+ 2
20 SHUTDOWN
19 VCC
V+ 3
18 GND
C1- 4
17 T1OUT
C2+
5
SP3224E
SP3225E
16
R1IN
C2- 6
15 R1OUT
V- 7
14 ONLINE
T2OUT 8
13 T1IN
R2IN 9
12 T2IN
R2OUT 10
11 STATUS
Typical Applications
■ Diagnostic/Serial ports on
■ SP3225E and SP3227E- high speed data rate of
1 Mbps.
■ Available in RoHS compliant, Lead Free
Packaging
embedded applications
■ Handheld Test Equipment
■ PC related Peripherals and
Equipment
■ Battery Powered Equipment
■ Point-of-sale Equipment
■ Set-top Box
DESCRIPTION
The SP3224E/3225E are 2-driver/2-receiver devices and the SP3226E/SP3227E are 1-
driver/1-receiver devices. All are ideal for computer peripherals, point-of-sale equipment,
consumer and embedded applications. These devices use an internal high-efficiency,
charge-pump power supply that requires only 0.1μF capacitors in 3.3V operation. This
charge pump and Exar’s driver architecture allow it to deliver compliant RS-232 perfor-
mance from a single power supply ranging from +3.0V to +5.5V. At voltages between 2.7V
and 3.0V the driver outputs are compliant with RS-562 and can interface to RS-232 over
short cables.
The Auto On-line® Plus feature allows the device to automatically “wake-up” during a shut-
down state upon detecting activity and to enter a low power shutdown if idle. This power
saving feature functions without system intervention or modifications to software or driv-
ers.
SElection TABLE
All devices feature 3.0V to 5.5V power supply, 4 small charge pump capacitors, and 15kV ESD
protection.
Device
Data Rate (bps)
No. of
READY pin Low-Power Shutdown
Drivers/Receivers
Package
SP3224E
SP3225E
250k
1M
2/2 Yes Auto On-Line® Plus 20 SSOP/TSSOP
2/2 Yes Auto On-Line® Plus 20 SSOP/TSSOP
SP3226E
250k
1/1 Yes Auto On-Line® Plus 16 SSOP/TSSOP
SP3227E
1M
1/1 Yes Auto On-Line® Plus 16 SSOP/TSSOP
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP3224E,3225E,3226E,3227E_101_081711
1 page  
TYPICAL PERFORMANCE CHARACTERISTICS:Curves
2.5
2
1.5
1
0.5
TxIn to RxOut Propagation Delay (us)
0
0
1000
2000
3000
Load Capacitance (pF)
4000
5000
SP3224E/SP3226E Transmitter Input to
Receiver Output Propagation Delay vs.
Load Capacitance
1.6
1.4
1.2
1
0.8
0.6
0.4
Tx0In.2to RxOut Propagation Delay (us)
0
0
1000
2000
3000
Load Capacitance (pF)
4000
5000
SP3225E/SP3227E Transmitter Input to
Receiver Output Propagation Delay vs.
Load Capacitance
30
25
20
SRneg
15
SRavg
10 SRpos
5
Transmitter Output Slew Rate (V/us)
0
0
1000
2000
3000
Load Capacitance (pF)
4000
5000
SP3224E/SP3226E Transmitter Output
Slew Rate vs. Load Capacitance
45
40
35
30 SRavg
25 SRneg
20
SRpos
15
10
Tra5nsmitter Output Slew Rate (V/us)
0
0
1000
2000
3000
Load Capacitance (pF)
4000
5000
SP3225E/SP3227E Transmitter Output
Slew Rate vs. Load Capacitance
6
V+
4
2
0
-2
Tr-a4nsmitter Output Voltage (V)
V-
-6
0
1000
2000
3000
Load Capacitance (pF)
4000
5000
SP3224E/SP3226E Transmitter Output
Voltage vs. Load Capacitance
6
V+
4
2
0
-2
Trasmitter Output Voltage (V)
-4
V-
-6
0 1000 2000 3000 4000 5000
Load Capacitance (pF)
SP3225E/SP3227E Transmitter Output
Voltage
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP3224E,3225E,3226E,3227E_101_081711
5 Page 
Description
The SP3224E and SP3225E are 2-driver/
2-receiver devices. The SP3226E and
SP3227E are 1-driver/1-receiver devices.
All are ideal for serial ports in embedded,
consumer, portable, or handheld applica-
tions. The transceivers meet the EIA/TIA-
232 and ITU-T V.28/V.24 communication
protocols for reliable serial communication.
The devices feature Exar’s proprietary and
patented (U.S. 5,306,954) on-board charge
pump circuitry that generates ±5.5V RS-
232 voltage levels from a single +3.0V to
+5.5V power supply.
THEORY OF OPERATION
rates fully loaded with 3KΩ in parallel with
1000pF (SP3224E/SP3226E), or 3KΩ in
parallel with 250pF (SP3225E/SP3227E)
ensuring compatibility with PC-to-PC com-
munication software. The slew rate of the
driver output on the SP3224E/SP3226E is
internally limited to a maximum of 30V/μs
in order to meet the EIA standards (EIA
RS-232D 2.1.7, Paragraph 5). The Slew
Rate of SP3225E/SP3227E is not limited
to enable higher speed data transfers. The
transition of the loaded output from HIGH
to LOW also meets the monotonic signal
transition requirements of the standard.
The SP3224E-SP3227E are ideal choic-
es for power sensitive designs. With the
Auto On-line® Plus enabled, the SP3224E-
SP3227E reduce supply current to 1µA
whenever the transceivers are in idle. In
shutdown, the internal charge pump and
the drivers will shut down. This feature al-
lows design engineers to address power
saving concerns without major design
changes.
Theory Of Operation
The SP3224E-SP3227E are made up of
four basic circuit blocks: 1. Drivers, 2. Re-
ceivers, 3. the Exar proprietary charge
pump, and 4. Auto On-line® Plus circuitry.
Drivers
The drivers are inverting level transmit-
ters that convert TTL or CMOS logic lev-
els to 5.0V EIA/TIA-232 levels with an
inverted sense relative to the input logic
levels. Typically, the RS-232 output volt-
age swing is +5.4V with no load and +5V
minimum fully loaded. The driver outputs
are protected against infinite short-circuits
to ground without degradation in reliabili-
ty. These drivers comply with the EIA-TIA-
232-F and all previous RS-232 versions.
Unused driver inputs should be connected
to GND or VCC.
The drivers can guarantee output data
Receivers
The receivers convert EIA/TIA-232 signal
levels to TTL or CMOS logic output lev-
els. Receivers remain active during device
shutdown. Since receiver input is usually
from a transmission line where long cable
lengths and system interference can de-
grade the signal, the inputs have a typical
hysteresis margin of 500mV. This ensures
that the receiver is virtually immune to noisy
transmission lines. Should an input be left
unconnected, an internal 5KΩ pulldown re-
sistor to ground will commit the output of
the receiver to a HIGH state.
Charge Pump
The charge pump is a Exar–patented de-
sign (US Patent #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 in-
put voltage (Vcc) over the +3.0V to +5.5V
range. This is important to maintain com-
pliant RS-232 levels regardless of power
supply fluctuations.
The charge pump operates in a discontinu-
ous mode using an internal oscillator. If the
output voltages are less than a magnitude
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
11
SP3224E,3225E,3226E,3227E_101_081711
11 Page | ||
| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet SP3224E.PDF ] | |
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