Overview
The SN74ACT245NSR is an octal bus transceiver with 3-state outputs, designed and manufactured by Texas Instruments. This component is optimized for asynchronous two-way communication between data buses, minimizing external timing requirements. The device allows data transmission from the A bus to the B bus or from the B bus to the A bus, depending on the logic level at the direction-control (DIR) input. The output-enable (OE) input can be used to disable the device, effectively isolating the buses. This makes it a versatile component for various bus interface applications where output ringing is a concern.
Key Specifications
| Parameter | Min | Typ | 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 | 4 | 7.5 | ns |
| tPHL Propagation Delay Time (A to B or B to A) | 1 | 4 | 8 | ns |
Key Features
- VCC operation range: 4.5V to 5.5V
- Inputs accept voltages up to 5.5V
- Maximum propagation delay time (tpd) of 8ns at 5V
- Inputs are TTL-voltage compatible
- Low drive and slow edge rates to minimize output ringing
- Output-enable (OE) input for bus isolation
- Direction-control (DIR) input for data direction control
Applications
- Pro Audio
- Video and Signage
- Appliances
- Factory Automation and Control
- Bus interface applications where output ringing is a concern
Q & A
- What is the primary function of the SN74ACT245NSR? The primary function is to facilitate asynchronous two-way communication between data buses.
- What is the operating voltage range of the SN74ACT245NSR? The operating voltage range is from 4.5V to 5.5V.
- How does the direction-control (DIR) input work? The DIR input determines the direction of data transmission between the A and B buses.
- What is the purpose of the output-enable (OE) input? The OE input can be used to disable the device, effectively isolating the buses.
- What are the typical applications of the SN74ACT245NSR? Typical applications include Pro Audio, Video and Signage, Appliances, and Factory Automation and Control.
- How does the SN74ACT245NSR minimize output ringing? It uses low drive and slow edge rates to minimize output ringing.
- What is the maximum propagation delay time (tpd) at 5V? The maximum propagation delay time is 8ns at 5V.
- Are the inputs TTL-voltage compatible? Yes, the inputs are TTL-voltage compatible.
- What is the recommended power supply configuration? Each VCC pin should have a good bypass capacitor to prevent power disturbance.
- How should the OE input be handled during power-up or power-down? The OE input should be tied to VCC through a pullup resistor to ensure a high-impedance state.
