Overview
The SN74LVC8T245-EP, produced by Texas Instruments, is an 8-bit dual-supply bus transceiver designed for voltage level translation and asynchronous communication between two data buses. This device is optimized to operate with two separate configurable power-supply rails, VCCA and VCCB, each of which can be set at any voltage between 1.65 V and 5.5 V. This flexibility allows for universal low-voltage bidirectional translation between various voltage nodes such as 1.8 V, 2.5 V, 3.3 V, and 5 V.
The device features direction-control (DIR) and output-enable (OE) inputs that manage the data transmission between the A and B ports. When OE is low and DIR is high, data is transmitted from the A bus to the B bus, and when OE is low and DIR is low, data is transmitted from the B bus to the A bus. If OE is high, both output ports are placed in a high-impedance state.
Key Specifications
| Parameter | Description | Values |
|---|---|---|
| VCCA and VCCB Voltage Range | Supply voltage for A and B ports | 1.65 V to 5.5 V |
| Operating Temperature Range | Free-air temperature range | –40°C to 85°C (commercial), –55°C to 125°C (military) |
| Package Types | Available package types | TSSOP (24), SOIC (24), VQFN (24) |
| Body Size (Nominal) | Package dimensions | TSSOP: 4.40 mm × 7.80 mm, SOIC: 7.50 mm × 15.40 mm, VQFN: 3.50 mm × 5.50 mm |
| ESD Protection | Human-Body Model, Machine Model, Charged-Device Model | 4000 V, 200 V, 1000 V respectively |
| Low-Level Output Current | Maximum output current at different VCC levels | 4 mA (1.65 V to 1.95 V), 8 mA (2.3 V to 2.7 V), 24 mA (3 V to 3.6 V), 32 mA (4.5 V to 5.5 V) |
Key Features
- Control Inputs VIH/VIL Levels: Referenced to VCCA voltage, ensuring proper logic level detection regardless of the supply voltage.
- VCC Isolation Feature: If either VCC input is at GND, all outputs are in the high-impedance state, preventing backflow current.
- Fully Configurable Dual-Rail Design: Each port can operate over the full 1.65-V to 5.5-V power-supply range, allowing for universal low-voltage bidirectional translation.
- Latch-Up Performance: Exceeds 100 mA per JESD 78, Class II, ensuring robust operation against latch-up conditions.
- ESD Protection: Exceeds JESD 22 standards for Human-Body Model, Machine Model, and Charged-Device Model, providing protection against electrostatic discharge.
- Partial-Power-Down Mode Operation: Ioff supports partial-power-down mode by disabling I/O output circuits to prevent backflow current.
Applications
The SN74LVC8T245-EP is suitable for various level-translation applications, particularly in systems where devices or subsystems operate at different interface voltages. It is ideal for interfacing between different voltage domains such as 1.8 V, 2.5 V, 3.3 V, and 5 V.
Common applications include:
- Level translation in mixed-voltage systems.
- Asynchronous communication between two data buses.
- Controlled baseline and extended product life cycle applications.
- Military and industrial environments requiring a wide temperature range.
Q & A
- What is the voltage range for VCCA and VCCB in the SN74LVC8T245-EP?
The voltage range for both VCCA and VCCB is from 1.65 V to 5.5 V.
- What are the available package types for the SN74LVC8T245-EP?
The device is available in TSSOP, SOIC, and VQFN packages.
- How does the direction-control (DIR) input affect data transmission?
The DIR input determines the direction of data transmission. A high on DIR allows data transmission from A to B, while a low on DIR allows data transmission from B to A.
- What is the purpose of the output-enable (OE) input?
The OE input enables or disables the output ports. When OE is low, the outputs are enabled; when OE is high, the outputs are in a high-impedance state.
- What is the maximum output current of the SN74LVC8T245-EP when powered by 5 V?
The maximum output current is up to 32 mA when the device is powered by 5 V.
- Does the SN74LVC8T245-EP support partial-power-down mode operation?
- What are the ESD protection ratings for the SN74LVC8T245-EP?
The device exceeds JESD 22 standards with 4000 V for Human-Body Model, 200 V for Machine Model, and 1000 V for Charged-Device Model.
- What is the operating temperature range for the SN74LVC8T245-EP?
The operating temperature range is –40°C to 85°C for commercial use and –55°C to 125°C for military use.
- How do I ensure proper device operation and minimize power consumption?
All unused or driven (floating) data inputs and control inputs must be held at logic HIGH or LOW (preferably VCCI or GND) to ensure proper device operation and minimize power consumption.
- What are some common applications of the SN74LVC8T245-EP?
