Explore MAX232 pins, signal names, electrical functions and connection guidance for each package.
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Click a lead or use the arrow keys. The notch marks the top; pin 1 is at the upper left.
Positive connection of the flying capacitor C1.
Connect C1 (1 µF) between pins 1 and 3; positive terminal to pin 1 if polarized.
Use 1 µF flying capacitors for this MAX232. Ceramic capacitors avoid polarity concerns; follow the marked +/− connections for polarized parts.
Positive voltage reservoir of the internal charge pump.
Connect the positive reservoir capacitor as shown in the manufacturer’s typical application. This is not a general-purpose supply.
Positive charge-pump reservoir. Use it for the reservoir capacitor, not as an external power output.
Negative connection of the flying capacitor C1.
Connect to the other side of C1 at pin 1.
Use 1 µF flying capacitors for this MAX232. Ceramic capacitors avoid polarity concerns; follow the marked +/− connections for polarized parts.
Positive connection of the inverting capacitor C2.
Connect C2 (1 µF) between pins 4 and 5; positive terminal to pin 4 if polarized.
Use 1 µF flying capacitors for this MAX232. Ceramic capacitors avoid polarity concerns; follow the marked +/− connections for polarized parts.
Negative connection of the inverting capacitor C2.
Connect to the other side of C2 at pin 4.
Use 1 µF flying capacitors for this MAX232. Ceramic capacitors avoid polarity concerns; follow the marked +/− connections for polarized parts.
Negative voltage reservoir of the internal charge pump.
Connect the negative reservoir capacitor to ground; observe capacitor polarity. Not a general-purpose supply.
Negative charge-pump reservoir. For a polarized reservoir capacitor, the positive terminal goes to ground.
Channel 2 transmit output at RS-232 voltage levels.
Connect to the remote receiver. Inverts the logic applied to T2IN (pin 10).
Bipolar RS-232 output. Typical levels are about ±7 V at 5 V supply, 25 °C and a 3 kΩ load. Keep it off microcontroller GPIO inputs.
Channel 2 receive input from an RS-232 line.
Connect to the remote transmitter. Its converted logic appears at R2OUT (pin 9).
RS-232 input only; specified input range is −30 to +30 V. The paired logic output is inverted.
Channel 2 receive output at TTL/CMOS logic levels.
Connect to the local UART receive input; paired with R2IN (pin 8).
Logic-level output for the local UART. A negative RS-232 input produces HIGH; a positive input produces LOW.
Channel 2 transmit input from TTL/CMOS logic.
Connect to the local UART transmit output; paired with T2OUT (pin 7).
LOW: 0.8 V or below. HIGH: 2 V or above. The paired RS-232 output is inverted; do not apply RS-232 voltage to this logic input.
Channel 1 transmit input from TTL/CMOS logic.
Connect to the local UART transmit output; paired with T1OUT (pin 14).
LOW: 0.8 V or below. HIGH: 2 V or above. The paired RS-232 output is inverted; do not apply RS-232 voltage to this logic input.
Channel 1 receive output at TTL/CMOS logic levels.
Connect to the local UART receive input; paired with R1IN (pin 13).
Logic-level output for the local UART. A negative RS-232 input produces HIGH; a positive input produces LOW.
Channel 1 receive input from an RS-232 line.
Connect to the remote transmitter; paired with R1OUT (pin 12).
RS-232 input only; specified input range is −30 to +30 V. The paired logic output is inverted.
Channel 1 transmit output at RS-232 voltage levels.
Connect to the remote receiver. Inverts the logic applied to T1IN (pin 11).
Bipolar RS-232 output. Typical levels are about ±7 V at 5 V supply, 25 °C and a 3 kΩ load. Keep it off microcontroller GPIO inputs.
Common ground reference for logic and the transceiver.
Connect to circuit ground and the serial connector’s signal ground.
0 V reference. Connect the local logic ground and the remote interface’s signal ground.
Positive supply input: 5 V nominal.
Use a regulated 4.5–5.5 V supply. Place the supply bypass capacitor close to VCC and GND.
5 V nominal; keep the supply within 4.5–5.5 V. Use a common supply with the connected logic circuit.
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