Overview
The SN74AVC8T245PW is an 8-bit dual-supply bus transceiver designed by Texas Instruments. This device is optimized for asynchronous communication between data buses and supports configurable voltage-level shifting. It operates with two separate power-supply rails, VCCA and VCCB, each of which can be set within the range of 1.2 V to 3.6 V. This flexibility allows for universal low-voltage bidirectional translation between various voltage nodes such as 1.2 V, 1.5 V, 1.8 V, 2.5 V, and 3.3 V. The device features 3-state outputs and is packaged in a 24-pin TSSOP (PW) package.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Package | TSSOP (PW) | - |
| Pins | 24 | - |
| Operating Temperature Range | -40 to 125 | °C |
| Supply Voltage Range (VCCA and VCCB) | 1.2 to 3.6 | V |
| Maximum Data Rates | 170 Mbps (VCCA < 1.8 V or VCCB < 1.8 V), 320 Mbps (VCCA ≥ 1.8 V and VCCB ≥ 1.8 V) | Mbps |
| I/O Voltage Tolerance | 4.6 V | V |
| Latch-Up Performance | Exceeds 100 mA per JESD 78, Class II | - |
| ESD Protection | 8000-V Human-Body Model, 200-V Machine Model, 1000-V Charged-Device Model | - |
Key Features
- Fully configurable dual-rail design allowing each port to operate over the full 1.4-V to 3.6-V power-supply range.
- I/Os are 4.6-V tolerant.
- Maximum data rates of 170 Mbps (VCCA < 1.8 V or VCCB < 1.8 V) and 320 Mbps (VCCA ≥ 1.8 V and VCCB ≥ 1.8 V).
- Latch-up performance exceeds 100 mA per JESD 78, Class II.
- ESD protection exceeds JESD 22 standards (8000-V Human-Body Model, 200-V Machine Model, 1000-V Charged-Device Model).
- VCC isolation feature – if either VCC input is at GND, all I/O ports are in the high-impedance state.
- Ioff supports partial power-down mode operation.
- Control inputs VIH/VIL levels are referenced to VCCA voltage.
Applications
The SN74AVC8T245PW is suitable for various applications requiring asynchronous communication between data buses with different voltage levels. This includes:
- Low-voltage bidirectional translation between different voltage nodes (e.g., 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V).
- Partial power-down mode applications where Ioff circuitry is necessary to prevent current backflow.
- Systems requiring high ESD protection and latch-up performance.
- Single-supply systems that may need to be upgraded or replaced with minimal PCB redesign.
Q & A
- What is the primary function of the SN74AVC8T245PW?
The SN74AVC8T245PW is an 8-bit dual-supply bus transceiver designed for asynchronous communication between data buses with configurable voltage-level shifting.
- What is the operating temperature range of the SN74AVC8T245PW?
The operating temperature range is -40°C to 125°C.
- What are the maximum data rates supported by the SN74AVC8T245PW?
The device supports maximum data rates of 170 Mbps (VCCA < 1.8 V or VCCB < 1.8 V) and 320 Mbps (VCCA ≥ 1.8 V and VCCB ≥ 1.8 V).
- What is the I/O voltage tolerance of the SN74AVC8T245PW?
The I/Os are 4.6-V tolerant.
- Does the SN74AVC8T245PW support partial power-down mode operation?
Yes, the device supports partial power-down mode operation using Ioff circuitry.
- What ESD protection does the SN74AVC8T245PW offer?
The device offers ESD protection exceeding JESD 22 standards (8000-V Human-Body Model, 200-V Machine Model, 1000-V Charged-Device Model).
- How does the VCC isolation feature work?
If either VCC input is at GND, all I/O ports are in the high-impedance state.
- Can the SN74AVC8T245PW be used in single-supply systems?
Yes, the device is compatible with single-supply systems and can be replaced later with a '245 function with minimal PCB redesign.
- What is the significance of the control inputs being referenced to VCCA voltage?
The control inputs VIH/VIL levels are referenced to VCCA voltage, ensuring proper operation based on the supply voltage of the A port.
- How do you ensure the high-impedance state during power up or power down?
To ensure the high-impedance state, OE should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
