I/O Expanders suit space constrained applications.

Press Release Summary:



Utilizing NiPdAu RoHS-compliant finish, 16-Bit Configurable I²C and SMBus I/O expanders, Models PCA9555, PCA9535, and PCA9539 provide general-purpose I/O expansion for most microprocessor families, allowing designers to save GPIOs for other functions. Model PCA9539 offers /RESET input, which can be used to initialize unit to its default state without de-powering it. All 3 devices are housed in QFN package.



Original Press Release:



TI Adds Three Configurable 16-Bit I/O Expanders to its Growing I2C Logic Portfolio



DALLAS (December 2, 2005) - Texas Instruments Incorporated (TI) (NYSE: TXN) today announced the release of three new 16-Bit Configurable I2C and SMBus I/O expanders. The PCA9555, PCA9535, and the PCA9539 16-bit I/O expanders provide general-purpose I/O expansion for most microprocessor families allowing designers to save the GPIOs on microprocessors for other important functions. These three I2C slave devices also utilize the industry preferred Nickel Palladium Gold (NiPdAu) RoHS compliant finish. (See: www.ti.com/i2c.)

As more features and processing requirements, such as LED control, hardware control monitors and humidity sensors in the computing space are added to applications, the limited numbers of GPIOs on microprocessors are becoming more valuable. By implementing these I/O Expanders, designers can utilize the microprocessor GPIOs for important functions and use the 16-Bit I/O expander for other duties, including system monitoring.

While all three devices have similar functionality, the PCA9539 is the premier part in this series of parts because it 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 in situations where the I2C bus has a glitch which prevents proper transmission of data between the microprocessor and slave devices (such as the PCA9539). Any incorrect data in the PCA9539 can then be eliminated through resetting it. Other slave devices without a /RESET input require their power supply to be lowered to 0V and then powered back up to Vcc for the slave device to return to its default state which can be inefficient and time consuming in the application.

Packaging, Pricing, and Availability
All three devices will be released in the ultra small QFN package making them ideal for space constrained applications. Currently, the PCA9555 is available in the industry standard SSOP, TSSOP, SOIC, and TVSOP packages. Budgetary pricing for the PCA9555DGVR (TVSOP) is set at $1.25 in quantities of 1,000. The PCA9535 is available in the industry standard SSOP, TSSOP, SOIC, and TVSOP packages. Budgetary pricing for the PCA9535DGVR (TVSOP) is set at $1.25 in quantities of 1,000. The PCA9539 is 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.

These new devices join other I2C devices in the Standard Linear and Logic Must Have (www.ti.com/musthave) product offerings. TI's Must Have products are a select group of Standard Linear and Logic products that provide a focused priority for the customer.

The inter-integrated circuit (I²C) bus consists of two active wires; the bidirectional serial data (SDA) line and the bidirectional serial clock (SCL) line.

PCF
The PCF8574 and PCF8574A provide an interface to most microcontroller families via the I²C bus for general purpose remote I/O expansion. With these devices, the SCL line is unidirectional, from the microprocessor to the device. The PCF8574 and PCF8574A are functionally the same, but differ in their I²C addresses. By using the PCF8574 or PCF8574A or both, circuit designers can greatly simplify complex glue-logic interface circuit, increase I/O pin-count, reduce PCB area used, and improve system reliability.

PCA
Texas Instruments offers the PCA8550 nonvolatile 5-bit register, designed for the specific application of multiplexing hardware signals with software-controllable configuration data. The PCA8550 is designed to multiplex four bits of data from parallel inputs or from I²C input data stored in a nonvolatile register. An additional bit of register output also is provided, which is latched to prevent changes in the output value during the write cycle. The factory default for the contents of the register is all low. These stored values can be read from, or written to, using the I²C bus. The ability to control writing to the register is provided by the write protect (WP) input. The override (OVERRIDE) input forces all the register outputs to a low.

I²C Portfolio
PCA8550 Non-Volatile 5-Bit Registered Multiplexer with I²C Interface
PCA9306 Dual Bi-Directional I²C-Bus and SMBus Voltage Level-Translator
PCA9535 Remote 16-Bit I²C And SMBus, Low-Power I/O Expander With Interrupt Output And Config. Registers
PCA9539 Remote 16-Bit I²C And SMBus, Low-Power I/O Expander With Interrupt Output, Reset, & Config. Registers
PCA9546A 4-Channel I²C and SMBus Multiplexer with Reset Functions
PCA9555 4-Channel I²C And SMBus Multiplexer With Reset Functions
PCF8574 Remote 8-Bit I/O Expander for I²C-Bus
PCF8574A Remote 8-Bit I/O Expander for I²C-Bus
PCF8575 Remote 16-Bit I²C and SMBus I/O Expander with Interrupt Output
PCF8575C Remote 16-Bit I²C and SMBus I/O Expander with Interrupt Output

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