±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V,

Up to 1Mbps, True RS-232 Transceivers

______________________________________________________________________________________

13

Figure 7. Loopback Test Circuit

2

µs/div

T1IN

T1OUT

R1OUT

5V/div

5V/div

5V/div

C1–C4 = 0.1

µF

Figure 8. MAX3241E Loopback Test Result at 120kbps

2

µs/div

T1IN

T1OUT

R1OUT

5V/div

5V/div

5V/div

µF

Figure 9. MAX3241E Loopback Test Result at 250kbps

+5V

0

+5V

0

-5V

+5V

0

T_IN

T_OUT

5k

Ω + 250pF

R_OUT

400ns/div

C1–C4 = 0.1

µF

Figure 10. MAX3237E Loopback Test Result at 1000kbps

MAX3222E

MAX3232E

MAX3237E

MAX3241E

MAX3246E

5k

Ω

R_ IN

R_ OUT

C2-

C2+

C1-

C1+

V-

V+

C4

C3

C1

C2

0.1

µF

T_ OUT

T_ IN

GND

1000pF

Transmitter Outputs Recovering

from Shutdown

Figure 3 shows two transmitter outputs recovering from

shutdown mode. As they become active, the two trans-

mitter outputs are shown going to opposite RS-232 levels

(one transmitter input is high; the other is low). Each

transmitter is loaded with 3k

Ω in parallel with 2500pF.

The transmitter outputs display no ringing or undesir-

able transients as they come out of shutdown. Note that

the transmitters are enabled only when the magnitude

of V- exceeds approximately -3.0V.

Mouse Drivability

The MAX3241E is designed to power serial mice while

operating from low-voltage power supplies. It has

been tested with leading mouse brands from manu-

facturers such as Microsoft and Logitech. The

MAX3241E successfully drove all serial mice tested

and met their current and voltage requirements.