Overview
The SN74ACT245PW is an octal bus transceiver with 3-state outputs, manufactured by Texas Instruments. This device is designed for asynchronous two-way communication between data buses, minimizing external timing requirements. It operates within a VCC range of 4.5V to 5.5V, making it suitable for various applications where reliable bus communication is essential.
Key Specifications
| Parameter | Min | Max | Unit |
|---|---|---|---|
| VCC Supply Voltage | 4.5 | 5.5 | V |
| VIH High-level Input Voltage | 2 | 2 | V |
| VIL Low-level Input Voltage | 0.8 | 0.8 | V |
| IOH High-level Output Current | -24 | -24 | mA |
| IOL Low-level Output Current | 24 | 24 | mA |
| TA Operating Free-air Temperature | -40 | 85 | °C |
| tPLH Propagation Delay Time (A to B or B to A) | 1 | 8 | ns |
| tPHL Propagation Delay Time (A to B or B to A) | 1 | 9 | ns |
Key Features
- Operates within a VCC range of 4.5V to 5.5V
- Inputs accept voltages up to 5.5V
- Maximum propagation delay time of 8ns at 5V
- Inputs are TTL-voltage compatible
- 3-state outputs for bus isolation
- Low drive and slow edge rates to minimize output ringing
- Control-function implementation minimizes external timing requirements
Applications
- Professional Audio Systems
- Video and Signage Systems
- Appliances
- Factory Automation and Control Systems
- Bus interface applications where output ringing is a concern
Q & A
- What is the operating VCC range of the SN74ACT245PW?
The SN74ACT245PW operates within a VCC range of 4.5V to 5.5V.
- What is the maximum propagation delay time at 5V?
The maximum propagation delay time at 5V is 8ns.
- Are the inputs TTL-voltage compatible?
- How do the 3-state outputs function?
The 3-state outputs can be placed in a high-impedance state to isolate the buses when the output-enable (OE) is high.
- What is the purpose of the direction-control (DIR) input?
The direction-control (DIR) input determines the direction of data flow between the A and B buses.
- How should the output-enable (OE) be managed during power up or power down?
The output-enable (OE) should be tied to VCC through a pullup resistor to ensure the high-impedance state during power up or power down.
- What are the recommended bypass capacitor values for the power supply?
A 0.1 μF capacitor is recommended for single supply pins, and 0.01 μF or 0.022 μF for each power pin if there are multiple VCC pins.
- Why is it important to prevent inputs from floating?
Preventing inputs from floating is crucial to avoid excess ICC and ICCZ and to ensure proper device operation.
- What are some common applications of the SN74ACT245PW?
Common applications include professional audio systems, video and signage systems, appliances, and factory automation and control systems.
- What is the significance of the low drive and slow edge rates in the SN74ACT245PW?
The low drive and slow edge rates minimize output ringing, overshoot, and undershoot on the outputs.
