Overview
The SN74HC245NS 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, making it ideal for various bus interface applications. The SN74HC245NS 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. Additionally, the output-enable (OE) input can be used to disable the device, effectively isolating the buses.
Key Specifications
| Parameter | Min | Nom | Max | Unit |
|---|---|---|---|---|
| VCC Supply Voltage | 2 | 5 | 6 | V |
| VIH High-level Input Voltage (VCC = 2 V) | 1.5 | 1.5 | 1.5 | V |
| VIH High-level Input Voltage (VCC = 4.5 V) | 3.15 | 3.15 | 3.15 | V |
| VIH High-level Input Voltage (VCC = 6 V) | 4.2 | 4.2 | 4.2 | V |
| VIL Low-level Input Voltage (VCC = 2 V) | 0.5 | 0.5 | 0.5 | V |
| VIL Low-level Input Voltage (VCC = 4.5 V) | 1.35 | 1.35 | 1.35 | V |
| VIL Low-level Input Voltage (VCC = 6 V) | 1.8 | 1.8 | 1.8 | V |
| Δt/Δv Input Transition Rise/Fall Time (VCC = 2 V) | 1000 | 1000 | 1000 | ns |
| Δt/Δv Input Transition Rise/Fall Time (VCC = 4.5 V) | 500 | 500 | 500 | ns |
| Δt/Δv Input Transition Rise/Fall Time (VCC = 6 V) | 400 | 400 | 400 | ns |
| TA Operating Free-Air Temperature | −40 | 85 | °C |
Key Features
- Wide operating voltage range from 2 V to 6 V
- High-current 3-state outputs capable of driving bus lines directly or up to 15 LSTTL loads
- Control-function implementation minimizes external timing requirements
- 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 DIR input
- Output-enable (OE) input to disable the device and isolate the buses
- Low drive and slow edge rates to minimize output ringing, overshoot, and undershoot
Applications
The SN74HC245NS is suitable for a multitude of bus interface type applications where output ringing is a concern. It can be used in systems requiring asynchronous two-way communication between data buses, such as in microcontroller-based systems, LED drivers, relays, and other system boards.
Q & A
- What is the primary function of the SN74HC245NS?
The primary function of the SN74HC245NS is to facilitate asynchronous two-way communication between data buses (A and B) based on the logic level at the direction-control (DIR) input.
- What is the operating voltage range of the SN74HC245NS?
The operating voltage range of the SN74HC245NS is from 2 V to 6 V.
- How does the output-enable (OE) input function?
The output-enable (OE) input can be used to disable the device, effectively isolating the buses.
- What are the key features of the SN74HC245NS in terms of output capabilities?
The SN74HC245NS has high-current 3-state outputs that can drive bus lines directly or up to 15 LSTTL loads.
- Why is the SN74HC245NS useful in minimizing output ringing?
The SN74HC245NS has low drive and slow edge rates, which minimize output ringing, overshoot, and undershoot.
- What are some typical applications of the SN74HC245NS?
Typical applications include microcontroller-based systems, LED drivers, relays, and other system boards where bus interface is critical.
- What is the significance of the DIR input in the SN74HC245NS?
The DIR input determines the direction of data transmission between the A and B buses.
- How should unused inputs be handled to ensure proper device operation?
All unused inputs of the device must be held at VCC or GND to ensure proper device operation.
- What are the thermal characteristics of the SN74HC245NS?
The device has specified junction-to-ambient thermal resistance depending on the package type, such as 92.1°C/W for SSOP and 77.0°C/W for SOIC.
- What are the available package options for the SN74HC245NS?
The SN74HC245NS is available in various packages including SOIC (DW), SOP (NS), SSOP (DB), TSSOP (PW), and PDIP (N).
