### Overview of the LTC1380IS The **LTC1380IS** is a high-performance, single-ended 8-channel analog multiplexer (MUX) manufactured by Analog Devices (formerly Linear Technology). It is specifically designed to interface with 2-wire serial buses (I2C compatible), allowing a microcontroller to select one of eight analog inputs using a digital serial interface. --- ### Key Specifications | Parameter | Specification | | :--- | :--- | | **Channels** | 8 Single-Ended | | **Interface** | 2-Wire Serial (I2C Compatible) | | **Supply Voltage Range** | 2.7V to ±5V or 10V Single Supply | | **On-Resistance ($R_{ON}$)** | 70 $\Omega$ (Typical) | | **Package Type** | 16-Lead Plastic SO (Narrow) | | **Operating Temperature** | -40°C to 85°C (Industrial Grade) | --- ### Functional Components & Features #### 1. Serial Interface (I2C) Unlike standard multiplexers that use parallel GPIO pins for channel selection, the LTC1380IS uses a **2-wire interface (SDA/SCL)**. This significantly reduces the pin count required on the host microcontroller. It supports four programmable addresses using two address pins ($A0, A1$), allowing up to four LTC1380s on the same bus. #### 2. Analog Switch Matrix The core of the device consists of high-quality CMOS switches. * **Low Charge Injection:** Minimizes glitches and "sampling" noise when switching between channels. * **Rail-to-Rail Range:** The analog signals can swing across the entire power supply range. #### 3. Power-On Reset (POR) The device includes internal circuitry that ensures all switches are **OFF** (open) during power-up. This prevents accidental short circuits or undefined signal paths during system initialization. #### 4. Low Power Consumption The LTC1380IS is optimized for battery-powered applications, consuming very little supply current (typically in the microampere range) when the serial bus is idle. --- ### Typical Application Circuit Below is a conceptual representation of how the LTC1380IS integrates into a system: ```text [Microcontroller] [LTC1380IS] [Analog Sensors] SDA <--------------> SDA | CH0 <---- Sensor 1 SCL ---------------> SCL | CH1 <---- Sensor 2 | ... GND ---------------- GND | CH7 <---- Sensor 8 | VCC ---------------- VCC | COM ----> To ADC Input ``` ### Pinout Summary 1. **S0-S7:** Analog Inputs (Channels). 2. **COM:** Common Analog Output (Linked to the selected S-pin). 3. **V+ / V-:** Positive and Negative Power Supplies. 4. **SDA / SCL:** I2C Data and Clock lines. 5. **A0 / A1:** I2C Address Select pins. ---