MAX3223ECAP+ Maxim Integrated Products, MAX3223ECAP+ Datasheet - Page 12

• Manufacturer Part Number: MAX3223ECAP+
• Description: IC TXRX RS232 250KBPS SD 20SSOP
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX3223ECAP+

• Number Of Drivers/receivers: 2/2
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 20-SSOP
• Propagation Delay Time Ns: 0.15 us
• Operating Supply Voltage: 3 V to 5.5 V
• Supply Current: 0.3 mA
• Operating Temperature Range: 0 C to + 70 C
• Data Rate: 250 Kbps
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
When using the minimum required capacitor values,
make sure the capacitor value does not degrade exces-
sively with temperature. If in doubt, use capacitors with a
larger nominal value. The capacitor’s equivalent series
resistance (ESR) usually rises at low temperatures and
influences the amount of ripple on V+ and V-.
In most circumstances, a 0.1µF V
adequate. In applications that are sensitive to power-
supply noise, use a capacitor of the same value as the
charge-pump capacitor C1. Connect bypass capacitors
as close to the IC as possible.
Figure 8 shows two transmitter outputs when exiting
shut down mode. As they become active, the two trans-
mitter outputs are shown going to opposite RS-232 lev-
els (one transmitter output is high, the other is low).
Each transmitter is loaded with 3kΩ in parallel with
1000pF. The transmitter outputs display no ringing or
undesirable transients as they come out of shutdown,
and are enabled only when the magnitude of V-
exceeds approximately -3V.
The MAX3221E/MAX3223E/MAX3243E maintain the RS-
232 ±5.0V minimum transmitter output voltage even at
high data rates. Figure 9 shows a transmitter loopback
test circuit. Figure 10 shows a loopback test result at
120kbps, and Figure 11 shows the same test at 250kbps.
For Figure 10, all three transmitters were driven simulta-
neously at 120kbps into RS-232 loads in parallel with
1000pF. For Figure 11, a single transmitter was driven at
250kbps, and all three transmitters were loaded with an
RS-232 receiver in parallel with 1000pF.
The MAX3243E has been specifically designed to power
serial mice while operating from low-voltage power sup-
plies. It has been tested with leading mouse brands such
AutoShutdown Plus is a trademark of Maxim Integrated Products, Inc.
12
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Mouse Driveability (MAX3243E)
Power-Supply Decoupling
when Exiting Shutdown
Transmitter Outputs
CC
bypass capacitor is
High Data Rates
as Logitech and Microsoft. When tested, the MAX3243E
successfully drove all serial mice and met their respective
current and voltage requirements. The MAX3243E’s regu-
lated dual charge pump ensures the transmitters will sup-
ply at least ±5V during worst-case conditions. Figure 12a
shows the transmitter outputs under increasing load cur-
rent. The AutoShutdown feature does not work with a
mouse, so FORCEOFF and FORCEON should be con-
nected to V
a mouse driver test circuit. To achieve mouse driveability
with 1µA supply current when the port is inactive, use
parts with the AutoShutdown Plus™ feature (such as the
MAX3244E and MAX3245E).
Table 3. Required Capacitor Values
Figure 8. Transmitter Outputs Exiting Shutdown or Powering Up
5V/div
2V/div
3.15 to 3.6
3.0 to 3.6
4.5 to 5.5
3.0 to 5.5
V
(V)
CC
V
C1–C4 = 0.1μF
CC
CC
= 3.3V
. Figure 12b (on the following page) shows
C1, C
40μs/div
0.047
0.22
0.22
(µF)
0.1
BYPASS
C2, C3, C4
(µF)
0.22
0.33
0.1
FORCEON =
FORCEOFF
T2OUT
T1OUT
1