资 源 简 介
The TRS3243E device consists of three line drivers, five line receivers, and a dual charge-pump circuit with± 15-kV ESD (HBM and IEC61000-4-2, Air-Gap Discharge) and ± 8-kV ESD (IEC61000-4-2, Contact Discharge)protecTIon on serial-port connecTIon pins. The device meets the requirements of TIA/EIA-232-F and provides theelectrical interface between an asynchronous communicaTIon controller and the serial-port connector. Thiscombination of drivers and receivers matches that needed for the typical serial port used in an IBM PC/AT, orcompatible. The charge pump and four small external capacitors allow operation from a single 3-V to 5.5-Vsupply. In addition, the device includes an always-active noninverting output (ROUT2B), which allowsapplications using the ring indicator to transmit data while the device is powered down. The device operates atdata signaling rates up to 250 kbit/s and a maximum of 30-V/ µ s driver output slew rate.Flexible control options for power management are available when the serial port is inactive. Theauto-powerdown feature functions when FORCEON is low and FORCEOFF is high. During this mode ofoperation, if the device does not sense a valid RS-232 signal, the driver outputs are disabled. If FORCEOFF isset low, both drivers and receivers (except ROUT2B) are shut off, and the supply current is reduced to 1 µ A.Disconnecting the serial port or turning off the peripheral drivers causes the auto-powerdown condition to occur.Auto-powerdown can be disabled when FORCEON and FORCEOFF are high, and should be done when drivinga serial mouse. With auto-powerdown enabled, the device is activated automatically when a valid signal isapplied to any receiver input. The INVALID output is used to notify the user if an RS-232 signal is present at anyreceiver input. INVALID is high (valid data) if any receiver input voltage is greater than 2.7 V or less than – 2.7 Vor has been between – 0.3 V and 0.3 V for less than 30 µ s. INVALID is low (invalid data) if all receiver inputvoltages are between – 0.3 V and 0.3 V for more than 30 µ s. Refer to Figure 5 for receiver input levels.The TRS3243EC is characterized for operation from 0 ° C to 70 ° C. The TRS3243EI is characterized for operationfrom – 40 ° C to 85 ° C.
