The part number **75185-P20-R** typically refers to a high-speed integrated circuit designed for serial communication, most commonly known as a **Multiple RS-232 Driver and Receiver**. This specific IC is widely used to interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE). --- ### 1. General Specifications The 75185 series is designed to comply with the EIA/TIA-232-E standard. It combines multiple drivers and receivers into a single package to save board space. | Feature | Specification | | :--- | :--- | | **Component Type** | RS-232 Transceiver (Driver/Receiver) | | **Driver Count** | 3 Drivers | | **Receiver Count** | 5 Receivers | | **Data Rate** | Up to 120 kbps (standard) | | **Supply Voltage (Vcc)** | 4.5V to 5.5V | | **Positive Supply (Vdd)** | 7.5V to 15V | | **Negative Supply (Vss)** | -7.5V to -15V | | **Package Style** | TSSOP-20 (Thin Shrink Small Outline Package) | --- ### 2. Functional Description The device serves as a voltage level translator. It converts the low-voltage TTL/CMOS logic signals from a microcontroller or UART into the high-voltage bipolar signals required by the RS-232 standard. * **Drivers (Transmitters):** These take TTL/CMOS inputs and convert them to RS-232 levels (typically ±9V). They feature current-limiting outputs to protect against short circuits. * **Receivers:** These take RS-232 input levels and convert them back to 5V TTL/CMOS logic. They usually include hysteresis to provide noise immunity. --- ### 3. Pinout Configuration (20-Pin) The "P20" in the part number indicates a 20-pin configuration. Below is a generalized breakdown of the pin assignments: | Pin Category | Description | | :--- | :--- | | **Vcc / GND** | Logic power supply and ground. | | **Vdd / Vss** | Positive and negative power rails for RS-232 voltage levels. | | **Driver Inputs (DY)** | TTL/CMOS signal inputs from the controller. | | **Driver Outputs (DA)** | RS-232 signal outputs to the DB9/DB25 connector. | | **Receiver Inputs (RA)** | RS-232 signal inputs from the external device. | | **Receiver Outputs (RY)** | TTL/CMOS signal outputs to the controller. | --- ### 4. Part Number Suffix Breakdown * **75185:** The core functional family (Multiple RS-232 Transceiver). * **P20:** Indicates the pin count (20 pins). * **R:** Usually denotes **Tape and Reel** packaging for automated surface-mount assembly (SMT). --- ### 5. Common Applications * **Desktop PCs:** Older motherboard COM ports. * **Modems:** Interfacing digital logic with analog transmission equipment. * **Industrial Equipment:** Connecting PLCs or sensors to a central monitoring system. * **Embedded Systems:** Adding serial debugging ports to custom PCBs.