The **74ABT373CMSAMQB** is a high-performance integrated circuit (IC) belonging to the **Advanced BiCMOS Technology (ABT)** family. It is a transparent octal D-type latch with 3-state outputs, designed specifically for driving high-capacitance loads or low-impedance backplanes. --- ## 1. Technical Specifications Overview | Parameter | Value / Description | | :--- | :--- | | **Logic Family** | ABT (Advanced BiCMOS) | | **Function** | Octal D-Type Transparent Latch | | **Output Type** | 3-State (Tri-state) | | **Operating Voltage ($V_{CC}$)** | 4.5V to 5.5V | | **Current Drive ($I_{OH}/I_{OL}$)** | -32 mA / 64 mA (High Output Drive) | | **Propagation Delay** | ~3.5 ns to 5.0 ns (Typical) | | **Package Type** | MSOP/SSOP (Surface Mount) | | **Military/Space Grade** | Likely designated by "MQB" suffix (Mil-Spec) | --- ## 2. Key Internal Components & Features ### A. The Transparent Latch (D-Type) The device contains eight independent D-type latches. - When the **Latch Enable (LE)** input is **HIGH**, the $Q$ outputs follow the $D$ inputs (transparent mode). - When **LE** transitions to **LOW**, the data present at the $D$ inputs is latched and held at the $Q$ outputs. ### B. 3-State Output Control The device features an **Output Enable ($\overline{OE}$)** pin. - **$\overline{OE}$ LOW:** The latched data is presented to the output pins. - **$\overline{OE}$ HIGH:** The outputs enter a high-impedance (Hi-Z) state, effectively disconnecting the IC from the bus. ### C. BiCMOS Technology This chip combines **Bipolar** and **CMOS** technologies: - **CMOS** provides low static power consumption. - **Bipolar** provides high-speed switching and high current drive capabilities. --- ## 3. Pinout Configuration (Standard 20-Pin) | Pin Name | Function | | :--- | :--- | | $D_0 - D_7$ | Data Inputs | | $Q_0 - Q_7$ | 3-State Latch Outputs | | $LE$ | Latch Enable (Active High) | | $\overline{OE}$ | Output Enable (Active Low) | | $V_{CC}$ | Positive Supply Voltage | | $GND$ | Ground | --- ## 4. Part Number Breakdown (Suffix Meaning) The specific string `CMSAMQB` often denotes high-reliability or military-grade standards: * **74ABT373**: Core logic family and function. * **MSAM**: Often refers to a specific package variant (Small Outline / SSOP). * **QB**: Usually signifies Military Standard (MIL-STD-883) Class B processing, meaning the part is screened for extreme temperature ranges and reliability. --- ## 5. Logic Truth Table | $\overline{OE}$ | $LE$ | $D$ | Output ($Q$) | Status | | :---: | :---: | :---: | :---: | :--- | | L | H | H | H | Transparent (Output = Input) | | L | H | L | L | Transparent (Output = Input) | | L | L | X | $Q_0$ | Latched (Holds previous state) | | H | X | X | Z | High Impedance (Disconnected) | ---