Dallas, Tex. Texas Instruments Inc. has released three 16-bit configurable I²C and SMBus I/O expanders, the PCA9555, PCA9535, and PCA9539.
The 16-bit I/O devices are designed to expand general-purpose I/O functions (GPIO) for most microprocessor families. GPIOs are becoming more valuable on microprocessors as more features and processing requirements, such as LED control, hardware control monitors and humidity sensors in the computing space, are added to applications.
TI's 16-bit I/O expanders enable designers to use the microprocessor GPIOs for important functions and use the 16-bit I/O expander for other duties, including system monitoring.
While all three devices are similar in function, the PCA9539 offers a /RESET input. In an I²C system, the /RESET input can be used to initialize the PCA9539 to its default state without de-powering it. This is useful when the I²C bus has a glitch that can alter data transmission between the microprocessor and slave devices. Any incorrect data in the PCA9539 can be eliminated by resetting it.
Other slave devices without a /RESET input require their power supply to be lowered to 0-V and then powered back up to Vcc in order for them to return to their default state. According to TI, that process can be inefficient and time consuming in the application.
All three devices will be released in the ultra small QFN package for space-constrained applications. The PCA9555 and PCA9535 are available in the industry standard SSOP, TSSOP, SOIC, and TVSOP packages. Budgetary pricing for the PCA9555DGVR (TVSOP) and PCA9535DGVR (TVSOP) is set at $1.25 in quantities of 1,000.
The PCA9539 is also available in the industry standard SSOP, TSSOP, SOIC, and TVSOP packages. Budgetary pricing for the PCA9539DGVR (TVSOP) is set at $1.38 in quantities of 1,000.
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Texas Instruments Inc., 1-972-644-5580, www.ti.com