SP3222EUCY-L/TR Exar Corporation, SP3222EUCY-L/TR Datasheet - Page 9

• Manufacturer Part Number: SP3222EUCY-L/TR
• Description: 1Mbps, 3.0V To 5.5V RS-232 2-driver/2-receiver, Low-power Shutdown
• Manufacturer: Exar Corporation
• Type: Transceiverr

Specifications of SP3222EUCY-L/TR

• Number Of Drivers/receivers: 2/2
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP (0.173", 4.40mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 12. Loopback Test results at 250kbps
Figure 11. SP3222EU/SP3232EU Driver Loopback
Test Circuit
Figure 13. Loopback Test results at 1000Kbps
OUTPUTS
INPUTS
LOGIC
LOGIC
C2
C5
C1
+
+
+
0.1µF
0.1µF
0.1µF
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
C1+
C2+
C2-
TxIN
C1-
RxOUT
EN*
SP3222EU
SP3232EU
V
V
GND
CC
CC
5kΩ
*SHDN
TxOUT
* SP3222EU only
RxIN
250pF or 1000pF
V+
V-
V
C3
C4
CC
+
+
0.1µF
0.1µF
9
Since receiver input is usually from a trans-
mission 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.
Table 2. SP3222EU Truth Table Logic for Shutdown
and Enable Control
Charge Pump
The charge pump is an Exar-patended
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 sym-
metrical 5.5V power supplies. The internal
power supply consists of a regulated dual
charge pump that provides output voltages
of +/-5.5V regardless of the input voltage
(Vcc) over the +3.0V to +5.5V range.
In most circumstances, decoupling the
power supply can be achieved adequately
using a 0.1µF bypass capacitor at C5 (refer
to figures 9 and 10). In applications that are
sensitive to power-supply noise, decouple
Vcc to ground with a capacitor of the same
value as charge-pump capacitor C1. Physi-
cally connect bypass capcitors as close to
the IC as possible.
SHDN
0
0
1
1
EN
0
1
0
1
Tri-state
Tri-state
SP3222EU/SP3232EU_100_120810
TxOUT
Active
Active
DESCRIPTION
Tri-state
Tri-state
RxOUT
Active
Active