1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
High Data Rates
The MAX3224/MAX3226/MAX3244 maintain the RS-232
±5.0V minimum transmitter output voltage even at high
data rates. Figure 7 shows a transmitter loopback test
circuit. Figure 8 shows a loopback test result at
120kbps, and Figure 9 shows the same test at
250kbps. For Figure 8, all transmitters were driven
simultaneously at 120kbps into RS-232 loads in parallel
with 1000pF. For Figure 9, a single transmitter was dri-
ven at 250kbps, and all transmitters were loaded with
an RS-232 receiver in parallel with 250pF.
The MAX3225/MAX3227/MAX3245 maintain the RS-232
±5.0V minimum transmitter output voltage at data rates
up to 1Mbps (MegaBaud). Figure 10 shows a loopback
test result with a single transmitter driven at 1Mbps and
all transmitters loaded with an RS-232 receiver in paral-
lel with 250pF.
MAX3224–MAX3227/MAX3244/MAX3245
†
Mouse Driveability
The MAX3244/MAX3245 are specifically designed to
power serial mice while operating from low-voltage
power supplies. They have been tested with leading
mouse brands from manufacturers such as Microsoft
and Logitech. The MAX3244/MAX3245 successfully
T1IN
5V/div
T1IN
5V/div
5V/div
T1OUT
T1OUT
5V/div
R1OUT
V
CC
= 3.3V
2μs/div
5V/div
R1OUT
V
CC
= 3.3V
200ns/div
5V/div
Figure 8. MAX3224/MAX3226/MAX3244 Loopback Test Result
at 120kbps
Figure 10. MAX3225/MAX3227/MAX3245 Loopback Test
Result at 1Mbps
TRANSMITTER OUTPUT VOLTAGE (V)
T1IN
5V/div
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
0
V
CC
= 3.0V
V
OUT+
V
OUT+
T1OUT
5V/div
V
CC
V
OUT-
V
OUT-
R1OUT
V
CC
= 3.3V
2μs/div
5V/div
1
2
3
4
5
6
7
8
9
10
LOAD CURRENT PER TRANSMITTER (mA)
Figure 9. MAX3224/MAX3226/MAX3244 Loopback Test Result
at 250kbps
Figure 11a. MAX324_ Transmitter Output Voltage vs. Load
Current per Transmitter
13
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
