I/O Expanders
I/O expander interface integrated circuits are key components used to expand the number of input/output ports of a microcontroller or processor.
1. What are the Core Functions of I/O Expanders Interface ICs?
Port Expansion: Through bus interfaces such as I²C and SPI, additional GPIO (general input/output) ports are added to the main control chip (such as MCU) to solve the problem of insufficient native I/O resources.
Signal Conversion and Isolation: Provide level conversion (such as 1.8V↔5V) and data buffering to adapt to peripherals with different voltages; achieve bus isolation through tri-state buffering to avoid signal conflicts.
Flexible Configuration: Support the dynamic setting of port direction (input/output), output level, and interrupt trigger mode to enhance system control flexibility.
2. What are I/O Expanders Interface ICs Mainly Used for?
IoT Devices: Connect multiple sensors (temperature, humidity, light, etc.) or actuators to meet complex data acquisition and control needs.
Industrial Automation: Expand the I/O interface of PLC to control field devices such as relays and motor drivers; support industrial Ethernet communication.
Consumer Electronics: used for interface expansion of smart home, robots, and other equipment, simplifying the complexity of PCB wiring.
3. What are the Technical Features of I/O Expanders Interface ICs?
Communication Protocol: mainstream support I²C (pin saving), SPI (high-speed transmission), compatible with SMBus and other standards.
Electrical Performance: wide voltage operating range (1.65V–5.5V), high drive current (directly drive LED), low power mode.
Enhanced Function: built-in polarity reversal register (support high/low level valid), interrupt output pin, hardware address pin (multi-device cascade).
4. System Integration Method of I/O Expanders Interface ICs
1) Addressing and Expansion: unified addressing or independent addressing is adopted, and the system bus is connected through the line selection method and full address decoding method.
2) Expansion Scheme:
Parallel Expansion: simple I/O expansion is realized by a latch (such as 74LS373), which is low cost but occupies wiring resources.
Serial Expansion: efficient expansion through I²C/SPI interface chip (such as TCA9535) to reduce pin occupation.
5. Typical Model Examples of I/O Expanders Interface ICs
TCA9535: 16-bit I²C expander, supports 1.65V–5.5V wide voltage, provides interrupt output and address pin configuration.
Other Common Solutions: PCA9555 (built-in pull-up resistor), MAX7313 (SPI interface), etc.
6. What are the Design Advantages of I/O Expanders Interface ICs?
Simplified wiring: Only 2 wires (I²C) are required to achieve multi-channel I/O control, reducing PCB complexity.
Cost and power optimization: Reduce the pin requirements of the main control chip, and support low-power mode to extend battery life.
I/O expander interface IC has become a core component for solving I/O resource bottlenecks in embedded systems and industrial control through flexible interface expansion capabilities, especially suitable for multi-peripheral and high-integration application scenarios.