1 µA S u p p ly Cu rre n t , 1 Mb p s , 3 .0 V t o 5 .5 V,
RS -2 3 2 Tra n s c e ive rs w it h Au t o S h u t d o w n P lu s
–7/MAX3245
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.
Mo u s e Drive a b ilit y
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
drove all serial mice tested and met their respective
c urre nt a nd volta g e re q uire me nts . The MAX3244/
MAX3245 dual charge pump ensures the transmitters
will supply at least ±5V during worst-case conditions.
Figure 11a shows the transmitter output voltages under
increasing load current. Figure 11b shows a typical
mouse connection.
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.
5V/div
5V/div
5V/div
5V/div
5V/div
5V/div
T1IN
T1IN
T1OUT
T1OUT
R1OUT
R1OUT
V
CC
= 3.3V
V
CC
= 3.3V
200ns/div
2µs/div
Figure 8. MAX3224/MAX3226/MAX3244 Loopback Test Result
at 120kbps
Figure 10. MAX3225/MAX3227/MAX3245 Loopback Test
Result at 1Mbps
6
5
V
4
3
OUT+
V
= 3.0V
5V/div
5V/div
5V/div
T1IN
T1OUT
R1OUT
CC
2
V
1
OUT+
0
-1
-2
-3
-4
-5
-6
V
CC
V
OUT-
V
OUT-
V
CC
= 3.3V
0
1
2
3
4
5
6
7
8
9
10
2µs/div
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
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
