The **SN74LS85ML1** (commonly referred to in the 74-series family as the SN74LS85) is a high-speed **4-Bit Magnitude Comparator**. It is a TTL (Transistor-Transistor Logic) integrated circuit designed to compare two 4-bit binary or BCD words and determine their relative magnitude. --- ### 1. Functional Overview The device compares two 4-bit inputs: Word **A** ($A_3, A_2, A_1, A_0$) and Word **B** ($B_3, B_2, B_1, B_0$). It provides three outputs indicating whether: * $A > B$ * $A < B$ * $A = B$ ### 2. Pin Configuration & Key Components The IC typically comes in a 16-pin package. Below is a breakdown of the pin functions: | Pin Type | Name | Description | | :--- | :--- | :--- | | **Data Inputs** | $A_0 - A_3$ | Four bits of Word A | | **Data Inputs** | $B_0 - B_3$ | Four bits of Word B | | **Cascading Inputs** | $I_{A>B}, I_{AB}, Q_{AB$ inputs must be tied **LOW**. --- ### 4. Technical Specifications (LS Series) As part of the **Low-power Schottky (LS)** family, this chip balances speed and power consumption. | Parameter | Typical Value | | :--- | :--- | | **Supply Voltage ($V_{CC}$)** | 4.75V to 5.25V | | **Propagation Delay** | ~15ns to 24ns | | **Power Dissipation** | ~52 mW | | **Logic Level** | TTL (High > 2.0V, Low < 0.8V) | --- ### 5. Application Example (Simplified Logic) If you were using this in a digital thermostat, the SN74LS85 would compare the "Set Temperature" (Word A) against the "Current Temperature" (Word B). ```text Inputs: A = 1010 (Decimal 10) B = 0110 (Decimal 6) Result: - Pin (A > B) = HIGH - Pin (A < B) = LOW - Pin (A = B) = LOW ```