## ADM223ARS: Overview and Technical Details The **ADM223ARS** is a high-speed, multi-channel RS-232 line driver/receiver designed by Analog Devices. It is part of the ADM2xx family, which is widely used for serial communication interfaces between data terminal equipment (DTE) and data circuit-terminating equipment (DCE). --- ### 1. Key Technical Specifications The ADM223ARS is characterized by its integrated charge pump circuitry, allowing it to operate from a single +5V power supply while generating the necessary positive and negative voltages for RS-232 levels. | Parameter | Specification | | :--- | :--- | | **Supply Voltage (Vcc)** | +5V (±10%) | | **Data Rate** | Up to 120 kbps | | **Drivers (Transmitters)** | 4 | | **Receivers** | 5 | | **Package Type** | SSOP-28 (Shrink Small Outline Package) | | **Operating Temperature** | -40°C to +85°C | | **ESD Protection** | ±2 kV (Human Body Model) | --- ### 2. Core Functional Components The internal architecture of the ADM223ARS consists of three primary sections: 1. **On-Chip Charge Pump:** Consists of an internal oscillator and four external capacitors ($0.1\mu F$). It converts the +5V input into +10V and -10V to meet RS-232 output voltage requirements. 2. **Transmitter Section (Drivers):** Converts TTL/CMOS input levels into RS-232 voltage levels (typically ±9V). These drivers have internal current limiting and thermal shutdown protection. 3. **Receiver Section:** Converts incoming RS-232 signals (which can be as high as ±25V) back into 5V TTL/CMOS logic levels. --- ### 3. Pinout Configuration (Summary) The ADM223ARS utilizes a 28-lead SSOP. Below is a grouping of the essential pins: | Pin Category | Description | | :--- | :--- | | **C1+, C1-, C2+, C2-** | Connections for the external charge pump capacitors. | | **V+ / V-** | Outputs of the internal voltage converters. | | **T_IN / T_OUT** | Transmitter Logic Inputs and RS-232 Outputs. | | **R_IN / R_OUT** | RS-232 Receiver Inputs and Logic Outputs. | | **$\overline{SD}$ (Shutdown)** | Places the device into a low-power mode (<1 $\mu A$). | | **$\overline{EN}$ (Enable)** | Controls the receiver outputs (High Impedance state). | --- ### 4. Typical Application Circuit To use the ADM223ARS, you must connect four external capacitors as shown in the logic block below: ```text [5V Supply] ----> Vcc | [ADM223ARS] C1+ ---| 0.1uF |--- C1- C2+ ---| 0.1uF |--- C2- V+ ---| 0.1uF |--- GND V- ---| 0.1uF |--- GND | [TTL/CMOS IN] --> T_IN | T_OUT --> [RS-232 DB9] [Logic OUT] <-- R_OUT | R_IN <-- [RS-232 DB9] ``` --- ### 5. Features and Use Cases * **Low Power Shutdown:** Ideal for battery-powered peripherals. In shutdown mode, all drivers are disabled, but some receivers can remain active to "wake up" the system. * **Compatibility:** Fully meets EIA-232-E and CCITT V.28 specifications. * **Common Applications:** * Industrial PC serial ports. * Modems and POS terminals. * Diagnostic ports on embedded systems.