MAX232

The MAX232 was proposed by Charlie Allen and designed by Dave Bingham. ==Versions==

The later MAX232A is backward compatible with the original MAX232 but may operate at higher baud rates and can use smaller external capacitors 0.1 μF in place of the 1.0 μF capacitors used with the original device. The newer MAX3232 and MAX3232E are also backwards compatible, but operates at a broader voltage range, from 3 to 5.5 V. Pin-to-pin compatible versions from other manufacturers are ICL232, SP232, ST232, ADM232 and HIN232. Texas Instruments makes compatible chips, using MAX232 as the part number. ==Voltage levels==

The MAX232 translates a TTL logic 0 input to between +3 and +15 V, and changes TTL logic 1 input to between −3 and −15 V, and vice versa for converting from TIA-232 to TTL. (The TIA-232 uses opposite voltages for data and control lines, see RS-232 voltage levels.) ==Applications==

The MAX232(A) has two receivers that convert from RS-232 to TTL voltage levels, and two drivers that convert from TTL logic to RS-232 voltage levels. As a result, only two out of all RS-232 signals can be converted in each direction. Typically, the first driver/receiver pair of the MAX232 is used for TX and RX signals, and the second one for CTS and RTS signals. There are not enough drivers/receivers in the MAX232 to also connect the DTR, DSR, and DCD signals. Usually, these signals can be omitted when, for example, communicating with a PC's serial interface, or when special cables render them unnecessary. If the DTE requires these signals, a second MAX232 or some other IC from the MAX232 family can be used. ==Derivatives==

The MAX232 family was subsequently extended by Maxim to versions with four transmitters (the MAX234) and a version with four receivers and four transmitters (the MAX248), as well as several other combinations of receivers and transmitters. A notable addition is the MAX316x which is able to be electrically reconfigured between differential 5 V (RS-422 and RS-485) and single-ended RS-232 albeit at reduced voltage. ==References==