Overview
The PCA9555PWRE4, produced by Texas Instruments, is a 16-bit I2C-bus and SMBus I/O port expander designed to provide general-purpose remote I/O expansion for various microcontroller families. This device operates within a supply voltage range of 2.3 V to 5.5 V and is compatible with most microcontrollers via the I2C interface. It features 16 bits of parallel Input/Output (GPIO) expansion, making it suitable for applications requiring additional I/O ports such as ACPI power switches, sensors, push buttons, LEDs, and fans.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC Supply Voltage | 2.3 | - | 5.5 | V |
| SCL, SDA Input Voltage | -0.5 | - | 5.5 | V |
| IOH High-Level Output Current | - | - | -10 | mA |
| IOL Low-Level Output Current | - | - | 25 | mA |
| TA Operating Free-Air Temperature | -40 | - | 85 | °C |
| SCL Clock Frequency | 0 | - | 400 | kHz |
| Standby Current Consumption | - | - | 1 | μA |
Key Features
- Low Standby-Current Consumption of 1 μA Max
- I2C to Parallel Port Expander
- Open-Drain Active-Low Interrupt Output
- 5-V Tolerant I/O Ports
- Compatible With Most Microcontrollers
- 400-kHz Fast I2C Bus
- Address by Three Hardware Address Pins for Use of up to Eight Devices
- Polarity Inversion Register
- Latched Outputs With High-Current Drive Capability for Directly Driving LEDs
- ESD Protection Exceeds JESD 22 Standards (2000-V Human-Body Model, 200-V Machine Model, 1000-V Charged-Device Model)
- Internal Power-On Reset
- No Glitch on Power-Up
- Noise Filter on SCL/SDA Inputs
Applications
The PCA9555 is versatile and can be used in various applications, including:
- Servers
- ACPI power switches
- Sensors and monitoring systems
- Push buttons and user interfaces
- LED indicators and lighting systems
- Fans and motor control systems
Q & A
- What is the operating voltage range of the PCA9555?
The PCA9555 operates within a supply voltage range of 2.3 V to 5.5 V.
- What is the maximum clock frequency for the I2C bus on the PCA9555?
The maximum clock frequency for the I2C bus is 400 kHz.
- How many devices can share the same I2C bus using the PCA9555?
Up to eight devices can share the same I2C bus using the three hardware address pins (A0, A1, A2).
- What is the purpose of the Polarity Inversion Register in the PCA9555?
The Polarity Inversion Register allows the polarity of the Input Port register to be inverted, enabling active HIGH or active LOW operation.
- How does the PCA9555 handle power-on reset?
The PCA9555 has an internal power-on reset that sets the registers to their default values and initializes the device state machine when power is applied.
- What is the function of the open-drain interrupt output in the PCA9555?
The open-drain interrupt output is activated when any input state differs from its corresponding input port register state, indicating to the system master that an input state has changed.
- What kind of ESD protection does the PCA9555 offer?
The PCA9555 offers ESD protection that exceeds JESD 22 standards, including 2000-V Human-Body Model, 200-V Machine Model, and 1000-V Charged-Device Model.
- Can the PCA9555 directly drive LEDs?
Yes, the PCA9555 has latched outputs with high-current drive capability, allowing it to directly drive LEDs.
- Is the PCA9555 compatible with other I2C devices like the PCF8575?
The PCA9555 is pin-to-pin and I2C-address compatible with the PCF8575, but software changes are required due to the enhancements.
- What is the standby current consumption of the PCA9555?
The standby current consumption of the PCA9555 is 1 μA Max.
