Overview
The PCA9545A, manufactured by Texas Instruments, is a quad bidirectional translating switch designed for I2C and SMBus applications. This device allows a single I2C master to communicate with up to four downstream I2C slave devices. It features a programmable control register that enables the selection of any individual or combination of the four downstream channels. The PCA9545A also includes interrupt logic and a reset function, making it versatile for various system designs. The device supports voltage translation, enabling communication between devices operating at different voltage levels (1.8V, 2.5V, 3.3V, and 5V) without additional protection.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Supply Voltage Range | 2.3 V to 5.5 V | V |
| On-State Resistance (RON) | Up to 16 Ω | Ω |
| Propagation Delay Time (tpd) | 0.3 ns (CL = 15 pF), 1 ns (CL = 50 pF) | ns |
| Interrupt Valid Time (tiv) | 4 μs | μs |
| Interrupt Reset Delay Time (tir) | 2 μs | μs |
| Operating Temperature Range | -40°C to 85°C | °C |
| Package Type | 20-TSSOP, SOIC, TSSOP, VQFN, BGA | - |
| I/O Tolerance | 5.5 V tolerant | V |
Key Features
- 1-of-4 bidirectional translating switches for I2C and SMBus compatibility
- Four active-low interrupt inputs and one active-low interrupt output
- Active-low reset input to recover from stuck I2C bus conditions
- Two address terminals allowing up to four devices on the I2C bus
- Channel selection via I2C bus in any combination
- Power-up with all switch channels deselected
- Voltage translation capability to support different bus voltages (1.8V, 2.5V, 3.3V, and 5V)
- External pull-up resistors for bus voltage adjustment
Applications
- I2C and SMBus multiplexing in embedded systems
- Voltage translation between different voltage domains
- Interrupt handling in multi-device I2C/SMBus networks
- Industrial automation and control systems
- Consumer electronics with multiple I2C/SMBus devices
- Automotive systems requiring robust I2C/SMBus communication
Q & A
- What is the primary function of the PCA9545A?
The PCA9545A is a quad bidirectional translating switch that allows a single I2C master to communicate with up to four downstream I2C slave devices.
- What are the supported voltage ranges for the PCA9545A?
The PCA9545A supports supply voltage ranges from 2.3 V to 5.5 V and can translate between different bus voltages such as 1.8V, 2.5V, 3.3V, and 5V.
- How does the PCA9545A handle interrupts?
The PCA9545A has four active-low interrupt inputs and one active-low interrupt output that acts as an AND of the four interrupt inputs.
- What is the purpose of the reset function in the PCA9545A?
The active-low reset input allows the PCA9545A to recover from a situation where one of the downstream I2C buses is stuck in a low state.
- What types of packages are available for the PCA9545A?
The PCA9545A is available in various packages including 20-TSSOP, SOIC, TSSOP, VQFN, and BGA.
- Is the PCA9545A tolerant to higher input voltages?
- How is channel selection done on the PCA9545A?
- What happens during power-up of the PCA9545A?
- Can the PCA9545A be reset using power cycling?
- What are some common applications of the PCA9545A?
