PCA9535PWR

This 16-bit expander for the two-wire bidirectional bus (I2C) is designed to operate between 2.3V and 5.5V VCC. Through the I2C interface [serial clock (SCL), serial data (SDA)], it provides general-purpose remote I/O expansion for most microcontroller families. The PCA9535 consists of two 8-bit configuration (input or output selectable), input port, output port, and polarity inversion (active-high or active-low operation) registers. Upon power-up, the I/Os are configured as inputs. The system master controller can enable the I/Os as inputs or outputs by writing to the I/O configuration bits. The data for each input or output is stored in the corresponding input or output port register. The polarity of the input port register can be inverted using the polarity inversion register. All registers can be read by the system master. In case of a timeout or other improper operation, the system master can reset the PCA9535 by using the power-on reset function to place the registers in their default state and initialize the I2C/SMBus state machine. The PCA9535 open-drain interrupt (INT) output is activated when any input state differs from its corresponding input port register state and is used to indicate to the system master that the input state has changed. The INT can be connected to the interrupt input of a microcontroller. By sending an interrupt signal on this line, the remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via the I2C bus. Thus, the PCA9535 can remain a simple slave device. The device outputs (latched) have high-current drive capability for directly driving LEDs. The device has low current consumption. Although pin-to-pin and I2C address compatible with the PCF8575, software changes are required due to the enhancements. The PCA9535 is identical to the PCA9555, except for the removal of the internal I/O pullup resistor, which greatly reduces power consumption when the I/Os are held low. Three hardware pins (A0, A1, and A2) are used to program and vary the fixed I2C address and allow up to eight devices to share the same I2C bus or SMBus. The fixed I2C address of the PCA9535 is the same as the PCA9555, PCF8575, PCF8575C, and PCF8574, allowing up to eight of these devices in any combination to share the same I2C bus or SMBus.

Key features

• 1 μA low standby current consumption (maximum)
• I2C to parallel port expander
• Open-drain active-low interrupt output
• 5V-tolerant I/O ports
• Compatible with most microcontrollers
• 400kHz fast I2C bus
• 3 hardware address pins for addressing up to 8 devices
• Polarity inversion register
• Latched outputs with high-current drive capability for direct LED driving
• Latch-up performance exceeds 100mA per JESD 78 Class II
• ESD protection exceeds JESD 22 requirements
• 2000V Human Body Model (A114-A)
• 1000V Charged Device Model (C101)