The **UT3223L-R20-R** is a high-speed, low-power transceiver designed for RS-232 serial communication. It is commonly used in portable electronics and battery-powered systems due to its integrated charge pump and power-saving features. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Component Type** | RS-232 Transceiver | | **Number of Drivers/Receivers** | 3 Drivers / 5 Receivers | | **Operating Voltage** | 3.0V to 5.5V | | **Data Rate** | Up to 250 kbps (Min) | | **Package Type** | SSOP-20 (Shrink Small Outline Package) | | **Operating Temperature** | -40°C to +85°C | --- ### 2. Functional Characteristics #### A. Internal Charge Pump The device features a regulated internal charge pump that requires only four small external capacitors (0.1µF). This allows the chip to generate the necessary RS-232 output voltages (±5.5V) from a single low-voltage supply (3.3V or 5V). #### B. Auto-Powerdown Feature The "L" version often signifies high-efficiency power management. The UT3223L includes an **Auto-Powerdown** function: - It automatically enters a low-power state (1µA) when the serial cable is disconnected or the connected transmitters are inactive. - It wakes up automatically when a valid signal is detected on any receiver input. #### C. ESD Protection The I/O pins are typically reinforced with enhanced Electrostatic Discharge (ESD) protection to safeguard the internal circuitry from voltage spikes during cable plugging/unplugging. --- ### 3. Pinout Configuration (SSOP-20) *While exact pin numbers depend on the datasheet, the general distribution is as follows:* 1. **C1+, C1-, C2+, C2-**: Connections for external charge pump capacitors. 2. **V+, V-**: Boosted voltage outputs from the charge pump. 3. **T1IN - T3IN**: TTL/CMOS level inputs (from the MCU). 4. **T1OUT - T3OUT**: RS-232 level outputs (to the DB9/Connector). 5. **R1IN - R5IN**: RS-232 level inputs (from the outside world). 6. **R1OUT - R5OUT**: TTL/CMOS level outputs (to the MCU). 7. **EN / SHDN**: Enable and Shutdown control pins. --- ### 4. Typical Applications * **Battery-powered equipment:** Handheld terminals, scanners, and PDAs. * **Telecommunications:** Modems and diagnostic ports. * **Industrial Control:** Interfacing microcontrollers (TTL) with legacy industrial hardware (RS-232).