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  • 8-bit I2C and SMBus low power I/O Port

  • Created: Jan 27, 2014

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The System Management Bus (SMBus) is a single-ended simple two-wire bus for the purpose of lightweight communication. Most commonly it is found in computer motherboards for communication with the power source for ON/OFF instructions. It is derived from I²C for communication with low-bandwidth devices on a motherboard, especially power related chips such as a laptop's rechargeable battery subsystem. Other devices might include temperature, fan or voltage sensors, lid switches and clock chips. PCI add-in cards may connect to an SMBus segment. While I²C is a multimaster serial single-ended computer bus invented by the Philips semiconductor division, today NXP Semiconductors, and used for attaching low-speed peripherals to a motherboard, embedded system, cellphone, or other digital electronic devices.

The PCA9538 is a 16-pin CMOS device that provides 8 bits of General Purpose parallel Input/output (GPIO) expansion with interrupt and reset for I²C -bus/SMBus applications and was developed to enhance the NXP Semiconductors family of I²C-bus Input/Output expanders. The Input/Output expanders provide a simple solution when additional Input/Output is needed for ACPI power switches, sensors, push buttons, LEDs, fans, etc. The PCA9538 consists of an 8-bit Configuration register (input or output selection), 8-bit Input Port register, 8-bit Output Port register and an 8-bit Polarity Inversion register (active HIGH or active LOW operation). The system master can enable the Input/Outputs as either inputs or outputs by writing to the I/O configuration bits. The data for each input or output is kept in the corresponding Input Port or Output Port register. The polarity of the Input Port register can be inverted with the Polarity Inversion register.

These peripherals are foundation for innovation and development which will lead to a new technology. As it progress, complexity to its internal structure will be at its peak. But having all these integrated together will yield a successful result and its byproduct will be a more powerful I²CBus and SMBus system.



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