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USB232 Converter User Guide
1.7.5 RS232 Transceiver
The SP3244E/3245E (or MAX3243) is a 3-driver/5-receiver device. These devices use an internal high-
efficiency, charge-pump power supply that requires only 0.1µF capacitors for 3.3V single-supply operation.
This charge pump and Sipex’s driver architecture allow the SP3244E/3245E to deliver compliant RS-232
performance from a +5VDC power supply.
The Auto On-line® Plus feature (shutdown) allows the device to automatically enter a low power shutdown
mode if all receiver and driver inputs have been idle for 30 seconds. The device will “wake-up” from this
automatic shutdown state upon detecting activity. This power saving feature functions without system
intervention or modifications to software or drivers.
SP3244E supports serial data rates of 250kbps minimum under full load and while maintaining slew rates of
less than 30V/µs. SP3245E is capable of high speed communication of up to 1Mbps.
ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered
during handling and assembly. The driver output and receiver inputs of the SP3244E/3245E have extra
protection against static electricity. Sipex uses state-of-the-art structures to protect these pins against ESD of
±15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown,
and powered down. After an ESD event, the SP3244E/3245E will keep working without latch-up or
damage.
The transmitter outputs and receiver inputs of the SP3244E/3245E are characterized for protection to the
following limits:
• ±15kV using the Human Body Model
• ±8kV using the Contact Discharge method specified in IEC 1000-4-2
• ±15kV using the Air-Gap Discharge method specified in IEC 1000-4-2
