What Is the MAX232? RS-232 Level Converter: Pinout and Uses
The MAX232 is an interface IC that converts an MCU's TTL/CMOS UART signal to RS-232 (±) voltage levels. From a single 5 V, its charge pump makes the ± voltages, for which 4 external capacitors (typically 1 µF) are mandatory. It connects an MCU to a PC COM port or RS-232 devices; it has 2 drivers + 2 receivers.
The MAX232 is an interface IC that converts a microcontroller's TTL/CMOS serial (UART) signal to RS-232 voltage levels. From a single 5 V supply, its internal charge pump produces the ± voltages RS-232 needs. For the concept, see what is UART.
What is the MAX232 used for?
Connecting an MCU to a PC's RS-232 (COM) port or to industrial devices that use RS-232. An MCU UART uses 0–5 V logic; RS-232 uses ± (typically ±12 V). The MAX232 shifts levels both ways (2 drivers + 2 receivers).
MAX232 pinout (DIP-16)
| Pin | Function | Pin | Function |
|---|---|---|---|
| 1 | C1+ | 16 | VCC (+5 V) |
| 2 | V+ | 15 | GND |
| 3 | C1− | 14 | T1OUT (RS-232) |
| 4 | C2+ | 13 | R1IN (RS-232) |
| 5 | C2− | 12 | R1OUT (TTL) |
| 6 | V− | 11 | T1IN (TTL) |
| 7 | T2OUT | 10 | T2IN |
| 8 | R2IN | 9 | R2OUT |
Four external capacitors (typically 1 µF) connect to the C1–C2 and V+/V− pins — the charge pump uses them to make the ± voltages.
Limitations
- The 4 external capacitors are mandatory (it will not work without them).
- Point-to-point and short distance only; for multi-drop/long distance use RS-485 (MAX485).
- On a 3.3 V system use the MAX3232.
Equivalents and alternatives
- MAX3232 / SP3232: 3.3 V-compatible versions.
- ADM3202 / ICL232: close equivalents.
- MAX485: RS-485 for long distance/multi-drop.
Find it in our catalog
Use the MAX232 search.