This section provides an overview for io expanders as well as their applications and principles. Also, please take a look at the list of 6 io expander manufacturers and their company rankings.
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An IO expander is a semiconductor device used as a peripheral IC for a microcontroller.
Generally, the number of IO ports available as pin terminals of a microcontroller is limited. For example, if a microcontroller is to be used in multiple products, it is necessary to support both products with limited functions and products with advanced functions.
In such a case, the cost of the microcontroller is reduced by minimizing the number of pins of the microcontroller itself, and the microcontroller is mounted on a low-priced product. If the same microcontroller is used in a high-end product, the number of control pins will be insufficient, so IO expander is used to expand the IO ports.
The combination of a microcontroller and an IO expander can expand the system's expandability.
After a system, including a microcontroller, has been designed and released as a product, if the number of IO ports built into the microcontroller becomes insufficient when functionality is changed or expanded, an IO expanders are used to compensate for the missing IO ports.
Possible applications include, for example, controlling a 7-segment LED that requires many control pins, or as a very general input/output port.
IO expanders operate under control from a microcontroller, but since serial buses such as the I2C bus are generally used, they are not suitable for applications that require switching IO expander ports at high speed or reading data at high speed.
IO expanders are controlled by a microcontroller via a serial bus such as the I2C bus. In general, IO expanders are equipped with 8-Bit or 16-bit IO ports.
The microcontroller sets the input or output in bit units to the direction register for the port in the IO expanders.
After that, data is written or read by writing the specified data to the port input/output register. When set as an output port, the set data is output from each port of the IO expanders, and when set as an input port, data can be read from the set input port.
Furthermore, some types of IO expanders have a terminal that accepts interrupt input.
When a predetermined condition set in advance is met, the output of the interrupt pin of the IO expanders is activated.
By connecting this pin to the microcontroller's interrupt input, it is possible to activate the microcontroller's built-in interrupt. This function is useful when you want the microcontroller to respond instantly to an external event and control the system.
*Including some distributors, etc.
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Diodes Incorporated is a supplier for the consumer electronics, computing, communications, industrial, and automotive markets. Diodes Incorporated designs, manufactures, and supplies application-specific standard products in the discrete, logic, analog, and mixed-signal semiconductor markets worldwide. It focuses on low pin count semiconductor devices. Diodes specializes in semiconductor products, such as MOSFET, TVS, and performance Schottky rectifiers, transient voltage suppressors and other devices. It also provides analog products, such as power management devices comprising AC-DC and DC-DC converters, signaling devices, CMOS devices, and analog switches. Diodes Incorporated was incorporated in 1959 and is headquartered in Plano, Texas.
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