## 54ABT373CSCQB: Technical Overview The **54ABT373CSCQB** is a high-performance, radiation-hardened (or high-reliability) octal transparent latch with 3-state outputs. It belongs to the **Advanced BiCMOS Technology (ABT)** family, which combines the high drive capabilities of bipolar transistors with the low power consumption of CMOS technology. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Logic Type** | Octal D-Type Transparent Latch | | **Technology** | BiCMOS (ABT) | | **Voltage Supply Range** | 4.5V to 5.5V | | **Output Type** | 3-State (High Impedance) | | **Propagation Delay** | ~3.5 ns to 5.0 ns (Typical) | | **Operating Temperature** | -55°C to +125°C (Military Grade) | | **Package Type** | CQFP (Ceramic Quad Flat Pack) | | **Pins** | 20-pin / 28-pin variants (depending on package) | --- ### 2. Functional Components This device consists of eight identical latches with common control logic: 1. **D-Inputs (D0-D7):** Data inputs that receive the digital signal. 2. **Latch Enable (LE):** * When **High**, the latch is "transparent," and the outputs follow the inputs. * When **Low**, the data is latched (stored) and the outputs remain stable regardless of input changes. 3. **Output Enable (OE):** * When **Low**, the outputs are active. * When **High**, the outputs are placed in a high-impedance state (High-Z), effectively disconnecting them from the bus. 4. **3-State Outputs (Q0-Q7):** The final stage that drives the external bus. --- ### 3. Part Number Breakdown (Nomenclature) Understanding the suffix helps identify its specific application: * **54**: Indicates the Military/Aerospace temperature range (-55°C to 125°C). * **ABT**: Advanced BiCMOS Technology. * **373**: The specific logic function (Octal Transparent Latch). * **CSC**: Ceramic Surface Mount (referring to the package material). * **QB**: Quality level, often indicating a **Mil-Prf-38535** compliant device (Class Q). --- ### 4. Typical Applications Due to its high reliability and robust temperature range, this part is commonly used in: * **Avionics and Aerospace:** Data buffering for flight computers. * **Military Systems:** Secure communication hardware. * **Space Applications:** Handling data bus signals in harsh radiation environments. * **High-Speed Bus Interfacing:** Connecting microprocessors to memory or peripherals where low noise and high drive are required. --- ### 5. Truth Table Summary | OE | LE | D | Output (Q) | Mode | | :---: | :---: | :---: | :---: | :--- | | L | H | H | H | Transparent (High) | | L | H | L | L | Transparent (Low) | | L | L | X | Q0 | Latched (No Change) | | H | X | X | Z | High-Impedance | *(L=Low, H=High, X=Don't Care, Z=High Impedance)*