# MAX232

**Texas Instruments** · RS-232 transceiver · SOIC-16

Dual EIA/TIA-232 (RS-232) driver/receiver with an on-chip capacitive charge-pump voltage generator, in a SOIC-16 package. It produces the bipolar +/- line levels RS-232 needs from a single 5 V supply, so a UART's TTL TX/RX can talk to a legacy serial port. Two drivers and two receivers, with four external charge-pump capacitors. The classic TTL-to-RS-232 level shifter.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | C1+ | passive | Positive lead of the C1 charge-pump flying capacitor (typ. 1µF). Connect to C1- (pin 3) through the external capacitor. Part of the voltage-doubler stage that generates VS+. |
| 2 | VS+ | power_out | Positive charge-pump output for the reservoir storage capacitor only. Nominally +8 to +10 V above GND, sourced through the C1 doubler. Bypass to GND with a 1µF capacitor; do not use as an external supply rail. |
| 3 | C1- | passive | Negative lead of the C1 charge-pump flying capacitor (typ. 1µF). Pairs with C1+ (pin 1) via the external capacitor to form the +5V→+10V doubler. |
| 4 | C2+ | passive | Positive lead of the C2 charge-pump flying capacitor (typ. 1µF). Connect to C2- (pin 5) through the external capacitor. Part of the inverter stage that generates VS−. |
| 5 | C2- | passive | Negative lead of the C2 charge-pump flying capacitor (typ. 1µF). Pairs with C2+ (pin 4) via the external capacitor to form the +10V→−10V inverter. |
| 6 | VS- | power_out | Negative charge-pump output for the reservoir storage capacitor only. Nominally −8 to −10 V below GND, generated by the C2 inverter stage. Bypass to GND with a 1µF capacitor; do not use as an external supply rail. |
| 7 | T2OUT | output | Driver-2 RS-232 line output to the remote RS-232 system. Swings between VS− and VS+ (typ. ±7V into a 3kΩ load), meeting TIA/EIA-232-F line levels. Short-circuit protected. |
| 8 | R2IN | input | Receiver-2 RS-232 line input from the remote RS-232 system. Accepts ±30V, typical input resistance 5 kΩ (3–7 kΩ), switching thresholds 1.2V (typ.) with 0.5V hysteresis. |
| 9 | R2OUT | output | Receiver-2 logic (TTL/CMOS) output to the local UART. VOH ≥ 3.5V at IOH = −1 mA; VOL ≤ 0.4V at IOL = 3.2 mA. |
| 10 | T2IN | input | Driver-2 logic (TTL/CMOS) data input from the local UART. VIH ≥ 2V, VIL ≤ 0.8V referenced to VCC = 5V. |
| 11 | T1IN | input | Driver-1 logic (TTL/CMOS) data input from the local UART. VIH ≥ 2V, VIL ≤ 0.8V referenced to VCC = 5V. |
| 12 | R1OUT | output | Receiver-1 logic (TTL/CMOS) output to the local UART. VOH ≥ 3.5V at IOH = −1 mA; VOL ≤ 0.4V at IOL = 3.2 mA. |
| 13 | R1IN | input | Receiver-1 RS-232 line input from the remote RS-232 system. Accepts ±30V, typical input resistance 5 kΩ (3–7 kΩ), switching thresholds 1.2V (typ.) with 0.5V hysteresis. |
| 14 | T1OUT | output | Driver-1 RS-232 line output to the remote RS-232 system. Swings between VS− and VS+ (typ. ±7V into a 3kΩ load), meeting TIA/EIA-232-F line levels. Short-circuit protected. |
| 15 | GND | power_in | Device ground / 0V reference for all supply rails and signal levels. |
| 16 | VCC | power_in | Positive supply voltage. Recommended 4.5–5.5V (nom. 5V); absolute max 6V. Typical supply current ICC = 8 mA with all outputs open. Decouple to GND close to the pin. |

## Key specifications

| Parameter | Value |
|---|---|
| Type | Dual RS-232 driver/receiver |
| Supply voltage | 5 V (single) |
| Line levels | Bipolar ± via charge pump |
| Channels | 2 drivers + 2 receivers |
| External caps | 4 (1 µF; 0.1 µF for MAX232A) |
| Standard | TIA/EIA-232-F |
| Package | SOIC-16 |
| Body (L×W×H) | 9.9 × 3.9 × 1.75 mm |

## Ordering variants

Same part, different packaging or reel option.

- `MAX232D (SOIC-16, tube)`
- `MAX232DR (SOIC-16, tape & reel)`

## CAD (KiCad official)

- Symbol: `Interface_UART:MAX232`
- Footprint: `Package_SO:SOIC-16_3.9x9.9mm_P1.27mm`
- 3D model: SOIC-16 (KiCad packages3D)
- 3D model files: `max232-etched.step` / `max232-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `max232.step` / `max232.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/max232.pdf) (27 pp, sha256 `47d45fefa0db5981`, retrieved 2026-08-17, tier: manufacturer)
- **Extractor:** `ds2sf` (Claude) — every pin and dimension is cited to a datasheet page; refuses to fabricate.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/max232-datasheet.pdf)