ANALOG MULTIPLEXER/DEMULTIPLEXER# Technical Documentation: HCF4097BEY 8-Channel Analog Multiplexer/Demultiplexer
Manufacturer : STMicroelectronics
Document Version : 1.0
Last Updated : October 2023
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## 1. Application Scenarios
### 1.1 Typical Use Cases
The HCF4097BEY is a monolithic integrated circuit fabricated in Metal Oxide Semiconductor technology, serving as an 8-channel analog multiplexer/demultiplexer with three address inputs (A0, A1, A2) and an active-low enable input (E). Its primary function is to route analog or digital signals from multiple sources to a single destination (multiplexing) or from a single source to multiple destinations (demultiplexing).
Key operational modes include:
- Signal Routing in Data Acquisition Systems : Connecting multiple sensors (temperature, pressure, voltage) to a single ADC input, reducing component count and system cost.
- Audio/Video Signal Switching : Selecting between multiple audio or low-frequency video sources in consumer electronics or professional AV equipment.
- Programmable Gain Amplifier Configuration : Switching between different feedback resistors in op-amp circuits to create variable gain stages.
- Digital Logic Expansion : Extending I/O capabilities of microcontrollers with limited pins by multiplexing control signals.
- Battery Monitoring Systems : Sequentially measuring voltages of individual cells in battery packs using a single measurement circuit.
### 1.2 Industry Applications
Industrial Automation:
- PLC input/output expansion modules
- Multi-sensor monitoring in process control
- Motor control signal routing
Automotive Electronics:
- Infotainment system input selection
- Diagnostic port signal routing
- Climate control sensor multiplexing
Medical Devices:
- Patient monitoring equipment with multiple lead inputs
- Diagnostic equipment signal conditioning paths
- Portable medical instruments with limited space
Consumer Electronics:
- Home theater input switching
- Gaming peripheral interfaces
- Smart home controller signal routing
Telecommunications:
- Low-frequency signal routing in PBX systems
- Test equipment channel selection
- Modem line interface switching
### 1.3 Practical Advantages and Limitations
Advantages:
- Wide Voltage Range : Operates from 3V to 20V supply, compatible with both 5V and 3.3V systems
- Low Power Consumption : Typical quiescent current of 1μA at 5V, suitable for battery-powered applications
- High Noise Immunity : CMOS technology provides excellent noise rejection (0.45VDD noise margin typical)
- Break-Before-Make Switching : Prevents short-circuiting of input signals during channel transitions
- Bidirectional Operation : Can function as multiplexer or demultexer without circuit modification
- Wide Analog Signal Range : Can handle analog signals from VSS to VDD
Limitations:
- Limited Bandwidth : -3dB bandwidth typically 30MHz at 15V supply, unsuitable for high-frequency RF applications
- On-Resistance Variation : 270Ω typical on-resistance with ±100Ω variation across channels and temperature
- Charge Injection : Approximately 10pC typical, can cause voltage spikes in high-impedance circuits
- Maximum Switching Frequency : 12MHz typical at 10V, limiting high-speed applications
- No Overvoltage Protection : Inputs must remain within supply rails to prevent latch-up
- Temperature Sensitivity : On-resistance increases by approximately 0.5%/°C
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## 2. Design Considerations
### 2.1 Common Design Pitfalls and Solutions
Pitfall 1: Signal Degradation Due to On-Resistance
- Problem : Voltage drop across switch resistance affects signal integrity, especially in high-impedance circuits
- Solution : Buffer high-imped
