The **U74HC245G-R20-R** is a specific part number typically associated with **Unisonic Technologies (UTC)**. It represents an 8-bit bidirectional transceiver with 3-state outputs, based on High-Speed CMOS (HC) technology. --- ### ## 1. Part Number Breakdown Understanding the suffix and prefix helps in identifying the exact physical and electrical characteristics. | Component Segment | Description | | :--- | :--- | | **U74HC** | High-speed CMOS logic family (compatible with 74LS series). | | **245** | Functional type: Octal Bus Transceiver with 3-State Outputs. | | **G** | Halogen-free and Lead-free (Green) package. | | **R20** | Package Code (Typically indicates an **SSOP-20** package). | | **R** | Packing method (Tape and Reel). | --- ### ## 2. Core Functional Specifications The device is designed for asynchronous two-way communication between data buses. * **Direction Control (DIR):** Determines the direction of data flow (from A to B, or B to A). * **Output Enable ($\overline{OE}$):** When HIGH, it places the I/O pins in a high-impedance state (effectively disconnecting from the bus). * **Voltage Range:** Typically operates between **2.0V to 6.0V**. * **Current Output:** High current outputs can drive up to 15 LSTTL loads. --- ### ## 3. Pin Configuration Table (SSOP-20) The 74HC245 follows a standard industry pinout for 20-pin packages. | Pin Number | Symbol | Description | | :--- | :--- | :--- | | 1 | **DIR** | Direction Control Input | | 2 to 9 | **A1 - A8** | Data Inputs / Outputs (Side A) | | 10 | **GND** | Ground (0V) | | 11 to 18 | **B8 - B1** | Data Inputs / Outputs (Side B) | | 19 | **$\overline{OE}$** | Output Enable (Active Low) | | 20 | **Vcc** | Supply Voltage | --- ### ## 4. Technical Characteristics Below are the typical electrical parameters for the HC series transceiver: ```yaml Electrical_Properties: Vcc_Range: 2.0V to 6.0V Input_Logic_High: 0.7 * Vcc (Min) Input_Logic_Low: 0.3 * Vcc (Max) Propagation_Delay: ~8-12ns (at 5V Vcc) Operating_Temperature: -40°C to +85°C Output_Drive: +/- 6mA at 4.5V ``` --- ### ## 5. Common Applications * **Bus Interfacing:** Connecting a micro-controller to a shared data bus. * **Voltage Level Shifting:** Driving 5V CMOS logic from slightly lower voltage systems (within Vcc limits). * **Isolation:** Using the $\overline{OE}$ pin to isolate sections of a circuit to prevent data collisions.