Overview
The PCA9545APWT is a 4-channel, bidirectional translating I2C and SMBus switch produced by Texas Instruments. This device is designed to enable communication between a single I2C master device and multiple I2C slave devices, while also providing interrupt and reset functionalities. The PCA9545APWT supports voltage translation, allowing devices with different voltage levels (1.8-V, 2.5-V, 3.3-V, and 5-V) to communicate without additional protection. It features an active-low RESET input and four active-low interrupt inputs, which can be used to detect interrupts from connected slave devices.
Key Specifications
| Parameter | Min | Max | Unit |
|---|---|---|---|
| Operating Temperature | -40 | 85 | °C |
| VCC Voltage | 1.8 | 5.5 | V |
| Propagation Delay Time (RON = 20 Ω, CL = 15 pF) | 0.3 | ns | |
| Propagation Delay Time (RON = 20 Ω, CL = 50 pF) | 1 | ns | |
| Interrupt Valid Time | 4 | μs | |
| Interrupt Reset Delay Time | 2 | μs | |
| RESET Time | 500 | ns | |
| Package Type | TSSOP (20 pins) | ||
| Package Size | 6.5 mm x 4.4 mm |
Key Features
- I2C bus and SMBus compatible
- Four active-low interrupt inputs and one active-low interrupt output
- Active-low reset input to recover from stuck I2C bus conditions
- Voltage translation capability to allow communication between devices with different voltage levels (1.8-V, 2.5-V, 3.3-V, and 5-V)
- All I/O terminals are 5.5 V tolerant
- External pull-up resistors to set the desired voltage level for each channel
- Power-on reset (POR) function to reset the state machine by cycling the power supply
Applications
- Multi-master I2C bus systems where multiple masters need to communicate with multiple slaves
- Systems requiring voltage translation between different I2C or SMBus devices
- Embedded systems, industrial automation, and automotive applications where multiple I2C devices need to be managed
- Consumer electronics and IoT devices that require efficient I2C bus management
Q & A
- What is the PCA9545APWT used for?
The PCA9545APWT is used as a 4-channel, bidirectional translating I2C and SMBus switch to enable communication between a single I2C master device and multiple I2C slave devices.
- What voltage levels does the PCA9545APWT support?
The device supports voltage translation between 1.8-V, 2.5-V, 3.3-V, and 5-V devices.
- How does the reset function work on the PCA9545APWT?
The active-low RESET input resets the I2C state machine and causes all channels to be deselected. Additionally, a power-on reset (POR) function resets the state machine by cycling the power supply.
- What is the purpose of the interrupt inputs and output on the PCA9545APWT?
The four active-low interrupt inputs allow the master to detect interrupts from connected slave devices, and the single active-low interrupt output acts as an AND of the four interrupt inputs.
- What package types are available for the PCA9545APWT?
The PCA9545APWT is available in various packages including TSSOP (20 pins), TVSOP, SOIC, VQFN, and BGA.
- What is the operating temperature range of the PCA9545APWT?
The operating temperature range is from -40°C to 85°C.
- How does the PCA9545APWT handle propagation delay?
The propagation delay time is dependent on the load capacitance and the ON-state resistance of the switch, with specified times for different load capacitances (e.g., 0.3 ns for CL = 15 pF and 1 ns for CL = 50 pF).
- What is the significance of the power-on reset (POR) function?
The POR function resets the state machine by cycling the power supply, ensuring all channels are deselected upon power-up.
- Can the PCA9545APWT be used in multi-master I2C bus systems?
Yes, the PCA9545APWT is suitable for multi-master I2C bus systems where multiple masters need to communicate with multiple slaves.
- Are the I/O terminals of the PCA9545APWT voltage tolerant?
Yes, all I/O terminals are 5.5 V tolerant.
