Transceivers Using Four 0.1µF External Capacitors
Power-Supply Decoupling
In most circumstances, a 0.1µF bypass capacitor isadequate. In applications that are sensitive to power-supply noise, decouple VCCto ground with a capacitorof the same value as charge-pump capacitor C1. Connectbypass capacitors as close to the IC as possible.
MAX3222/MAX3232/MAX3237/MAX3241
Operation Down to 2.7V
Transmitter outputs will meet EIA/TIA-562 levels of±3.7V with supply voltages as low as 2.7V.
Transmitter Outputs when
Exiting Shutdown
Figure 3 shows two transmitter outputs when exitingshutdown mode. As they become active, the two trans-mitter outputs are shown going to opposite RS-232 lev-els (one transmitter input is high, the other is low).Each transmitter is loaded with 3k in parallel with2500pF. The transmitter outputs display no ringing orundesirable transients as they come out of shutdown.Note that the transmitters are enabled only when themagnitude of V- exceeds approximately 3V.
Mouse Driveability
The MAX3241 has been specifically designed to powerserial mice while operating from low-voltage power sup-plies. It has been tested with leading mouse brands frommanufacturers such as Microsoft and Logitech. TheMAX3241 successfully drove all serial mice tested andmet their respective current and voltage requirements.Figure 4a shows the transmitter output voltages underincreasing load current at 3.0V. Figure 4b shows a typicalmouse connection using the MAX3241.
Figure 3. Transmitter Outputs when Exiting Shutdown or Powering Up
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