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SP3223ECA-L Datasheet, PDF (10/23 Pages) Sipex Corporation – Intelligent +3.0V to +5.5V RS-232 Transceivers | |||
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DEVICE: SP3223
SHUTDOWN
EN
0
0
TXOUT
High Z
0
1
High Z
1
0
Active
1
1
Active
RXOUT
Active
High Z
Active
High Z
Table 2. SHUTDOWN and EN Truth Tables
Note: In AUTO ON-LINE® Mode where ONLINE =
GND and SHUTDOWN = VCC, the device will shut down
if there is no activity present at the Receiver inputs.
Receivers
The receivers convert ±5.0V EIA/TIA-232
levels to TTL or CMOS logic output levels.
Receivers have an inverting output that can be
disabled by using the EN pin.
Receivers are active when the AUTO ON-LINE®
circuitry is enabled or when in shutdown.
During the shutdown, the receivers will continue
to be active. If there is no activity present at the
receivers for a period longer than 100µs or when
SHUTDOWN is enabled, the device goes into a
standby mode where the circuit draws 1µA.
Driving EN to a logic HIGH forces the outputs of
the receivers into high-impedance. The truth
table logic of the SP3223 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, the inputs
have a typical hysteresis margin of 300mV. This
ensures that the receiver is virtually immune to
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.
+3V to +5V
+
C5 0.1µF
+
C1 0.1µF
+
C2 0.1µF
2 C1+
4 C1-
5 C2+
6 C2-
TTL/CMOS
INPUTS
T1IN
TXIN
19
VCC
V+ 3
SP3223
V- 7
T1OUT
TXOUT
+
C3 0.1µF
C4 0.1µF
+
TTL/CMOS
OUTPUTS
R1OUT
R1IN
5Kâ¦
VCC
To µP Supervisor
Circuit
RXOUT
1 EN
RXIN
5Kâ¦
20 SHUTDOWN
14 ONLINE
11 STATUS
GND
18
1000pF
1000pF
Figure 12. Loopback Test Circuit for RS-232 Driver
Data Transmission Rates
Charge Pump
The charge pump is a Sipexâpatented design
(U.S. 5,306,954) and uses a unique approach
compared to older lessâefficient designs. The
charge pump still requires four external
capacitors, but uses a fourâphase voltage
shifting technique to attain symmetrical 5.5V
power supplies. The internal power supply
T1 IN
T1 OUT
R1 OUT
Date: 12/16/04
Figure 13. Loopback Test Circuit result at 235Kbps
(All Drivers Fully Loaded)
SP3223 +3.0V to +5.5V RS-232 Transceivers
10
© Copyright 2004 Sipex Corporation
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