SP3221E Datasheet, PDF (8/18 Pages) Sipex Corporation – Intelligent +3.0V to +5.5V RS-232 Transceiver

DEVICE: SP3221E
SHUTDOWN
EN
0
0
T_XOUT
High Z
R_XOUT
Active
0
1
High Z High Z
1
0
Active
Active
1
1
Active
High Z
Table 2. SHUTDOWN and EN Truth Tables
Note: In Auto-Online Mode where ONLINE = GND and
SHUTDOWN = V_CC, the device will shut down if there is
no activity present at the Receiver inputs.
Receivers
The receiver converts ±5.0V EIA/TIA-232
levels to TTL or CMOS logic output levels. The
receiver has an inverting output that can be
disabled by using the EN pin.
The receiver is active when the Auto-Online
circuitry is enabled or when in shutdown.
During the shutdown, the receiver will continue
to be active.
Driving EN to a logic HIGH forces the output of
the receiver into high-impedance.
+3V to +5V
+
C5 0.1µF
+
C1 0.1µF
+
C2 0.1µF
2 _C1+
4 C1-
5 C2+
6 C2-
19
VCC
SP3221E
V+ ³
+
C3 0.1µF
V- ⁷
C4 0.1µF
+
TTL/CMOS
INPUTS
11 T₁IN
T₁OUT 13
TTL/CMOS
OUTPUTS
9 ^R1^OUT
R₁IN ₈
5KΩ
1000pF
VCC
To µP Supervisor
Circuit
1 _EN
20 _SHUTDOWN
14 _ONLINE
11 _STATUS
GND
18
Figure 6. Loopback Test Circuit for RS-232 Driver Data
Transmission Rates
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 5KΩ pulldown resistor
to ground will commit the output of the receiver
to a HIGH state.
T1 IN 1
[
T
]
T
T1 OUT 2
T
T
R1 OUT 3
Ch1 5.00V Ch2 5.00V M 5.00µs Ch1
0V
Ch3 5.00V
[
T
]
T
T1 IN 1
T1 OUT 2
T
T
R1 OUT 3
Ch1 5.00V Ch2 5.00V M 2.50µs Ch1
0V
Ch3 5.00V
Figure 7. Loopback Test Circuit Result at 250Kbps
(Driver Fully Loaded)
Figure 8. Loopback Test Circuit result at 235Kbps
(Driver Fully Loaded)
Date: 7/21/04
SP3221E +3.0V to +5.5V RS-232 Transceiver
8
© Copyright 2004 Sipex Corporation