Overview
The SN74LVC4245A, produced by Texas Instruments, is an 8-bit (octal) noninverting bus transceiver designed for asynchronous communication between data buses. This device features two separate supply rails: the B port operates at 3.3 V (VCCB), and the A port operates at 5 V (VCCA), enabling translation between 3.3-V and 5-V environments. The device can transmit data from the A bus to the B bus or vice versa, controlled by the direction-control (DIR) input. Additionally, the output-enable (OE) input allows the device to be disabled, effectively isolating the buses. The control circuitry is powered by VCCA.
Key Specifications
| Parameter | Test Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| VCCA Supply Voltage Range | - | -0.5 | - | 6.5 | V |
| VI Input Voltage Range (A port) | - | -0.5 | - | VCCA + 0.5 | V |
| VO Output Voltage Range (A port) | - | -0.5 | - | VCCA + 0.5 | V |
| Continuous Output Current | - | - | - | ±50 | mA |
| Continuous Current through Each VCCA or GND | - | - | - | ±100 | mA |
| Tstg Storage Temperature Range | - | -65 | - | 150 | °C |
| tPHL (A to B) | VCCA = 5 V ± 0.5 V, VCCB = 2.7 V to 3.6 V | 6.1 | - | - | ns |
| tPLH (A to B) | VCCA = 5 V ± 0.5 V, VCCB = 2.7 V to 3.6 V | 6.3 | - | - | ns |
| tPHL (B to A) | VCCA = 5 V ± 0.5 V, VCCB = 2.7 V to 3.6 V | 6.1 | - | - | ns |
| tPLH (B to A) | VCCA = 5 V ± 0.5 V, VCCB = 2.7 V to 3.6 V | 5 | - | - | ns |
Key Features
- 8-bit (octal) noninverting bus transceiver with two separate supply rails (VCCA = 5 V, VCCB = 3.3 V) for voltage translation between 3.3-V and 5-V environments.
- Direction-control (DIR) input to select data transmission direction between A and B buses.
- Output-enable (OE) input to disable the device and isolate the buses.
- Control circuitry powered by VCCA.
- 24 mA drive at 3-V supply, suitable for heavier loads and longer traces.
- Low VIH allows for 3.3-V to 5-V translation.
- CMOS technology with balanced output drive.
- Available in DB (SSOP), DW (SOIC), and PW (TSSOP) packages.
Applications
The SN74LVC4245A is designed for various bus interface applications where output drive or PCB trace length is a concern. It is particularly useful in systems that require asynchronous communication between data buses operating at different voltage levels.
- Bus interface applications in mixed-voltage systems.
- Data translation between 3.3-V and 5-V environments.
- Systems requiring high drive capability for longer traces or heavier loads.
- General-purpose logic circuits where voltage translation is necessary.
Q & A
- What is the primary function of the SN74LVC4245A?
The SN74LVC4245A is an 8-bit noninverting bus transceiver designed for asynchronous communication between data buses, allowing translation between 3.3-V and 5-V environments.
- What are the supply voltage ranges for the A and B ports?
The A port operates at VCCA = 4.5 V to 5.5 V, and the B port operates at VCCB = 2.7 V to 3.6 V.
- How is the direction of data transmission controlled?
The direction of data transmission is controlled by the direction-control (DIR) input.
- What is the purpose of the output-enable (OE) input?
The output-enable (OE) input can be used to disable the device, effectively isolating the buses.
- What are the package options available for the SN74LVC4245A?
The device is available in DB (SSOP), DW (SOIC), and PW (TSSOP) packages.
- What is the maximum continuous output current per pin?
The maximum continuous output current per pin is ±50 mA.
- What is the storage temperature range for the SN74LVC4245A?
The storage temperature range is –65°C to 150°C.
- What are the typical propagation delay times for the SN74LVC4245A?
The typical propagation delay times range from 5 ns to 6.7 ns depending on the direction of data transmission and load conditions.
- Why is the SN74LVC4245A suitable for applications with longer traces or heavier loads?
The device is suitable due to its 24 mA drive capability at 3-V supply, making it good for heavier loads and longer traces.
- What should be considered during the design and implementation of the SN74LVC4245A?
Care should be taken to avoid bus contention, and routing and load conditions should be considered to prevent ringing due to the high drive and fast edges.
