Overview
The SN74LVC8T245DBR, produced by Texas Instruments, is an 8-bit non-inverting bus transceiver with configurable dual power supply rails. This device enables bidirectional voltage level translation between two data buses operating at different voltage levels. The SN74LVC8T245 is optimized to operate with VCCA and VCCB set at any voltage between 1.65 V and 5.5 V, making it suitable 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 control inputs (DIR and OE) that are supplied by VCCA, allowing for the activation or deactivation of the output ports. It also includes a VCC isolation feature, which ensures that if either VCC input is at GND, all outputs are in the high-impedance state. This makes it ideal for asynchronous communication between two data buses and for partial-power-down applications.
Key Specifications
| Parameter | Condition | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| VCCA Supply Voltage Range | -0.5 | 6.5 | V | ||
| VCCB Supply Voltage Range | -0.5 | 6.5 | V | ||
| Input Voltage Range | -0.5 | 6.5 | V | ||
| Operating Free-Air Temperature | -40 | 85 | °C | ||
| Low-Level Output Current (IOL) | 1.65 V to 1.95 V | 4 | mA | ||
| Low-Level Output Current (IOL) | 2.3 V to 2.7 V | 8 | mA | ||
| Low-Level Output Current (IOL) | 3 V to 3.6 V | 24 | mA | ||
| Low-Level Output Current (IOL) | 4.5 V to 5.5 V | 32 | mA | ||
| Input Transition Rise or Fall Rate | 1.65 V to 1.95 V | 20 | ns/V | ||
| Input Transition Rise or Fall Rate | 2.3 V to 2.7 V | 20 | ns/V | ||
| Input Transition Rise or Fall Rate | 3 V to 3.6 V | 10 | ns/V | ||
| Input Transition Rise or Fall Rate | 4.5 V to 5.5 V | 5 | ns/V |
Key Features
- Fully configurable dual-rail design allows each port to operate over the full 1.65-V to 5.5-V power-supply range.
- VCC isolation feature – if either VCC input is at GND, all outputs are in the high-impedance state.
- Control inputs VIH/VIL levels are referenced to VCCA voltage.
- Latch-up performance exceeds 100 mA per JESD 78, Class II.
- ESD protection exceeds JESD 22 – 4000-V Human-Body Model, 200-V Machine Model, and 1000-V Charged-Device Model.
- Supports partial-power-down applications using Ioff circuitry to prevent damaging current backflow.
- Input circuitry on both A and B ports is always active and must have a logic HIGH or LOW level applied.
Applications
- Personal electronic devices: The SN74LVC8T245 is suitable for level-translation applications in personal electronics where different voltage levels are used.
- Industrial applications: It can be used in industrial settings where devices operate at various voltage levels.
- Enterprise and telecom systems: The device is useful in enterprise and telecom environments where voltage level translation is necessary for interoperability between different systems.
- Level-translation applications: It is ideal for interfacing devices or systems operating at different interface voltages.
Q & A
- What is the voltage range for VCCA and VCCB in the SN74LVC8T245?
VCCA and VCCB can be supplied at any voltage between 1.65 V and 5.5 V.
- How does the direction control (DIR) input work?
The DIR input controls 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 output ports are enabled; when OE is high, both output ports are in the high-impedance state.
- What is the VCC isolation feature?
If either VCC input is at GND, all outputs are in the high-impedance state, ensuring safe operation during power-up or power-down.
- What kind of ESD protection does the SN74LVC8T245 have?
The device has ESD protection exceeding JESD 22 – 4000-V Human-Body Model, 200-V Machine Model, and 1000-V Charged-Device Model.
- Can the SN74LVC8T245 be used in partial-power-down applications?
Yes, the device is fully specified for partial-power-down applications using Ioff circuitry to prevent damaging current backflow.
- What is the recommended way to handle unused I/Os?
It is recommended to tie all unused I/Os to GND to prevent excess ICC and ICCZ.
- What are the typical applications of the SN74LVC8T245?
The device is used in level-translation applications for interfacing devices or systems operating at different interface voltages.
- How does the device handle input transition rates?
The input transition rise or fall rate varies depending on the voltage range, with rates from 5 ns/V to 20 ns/V.
- What are the package options available for the SN74LVC8T245?
The device is available in various packages including DBV (SSOP, 24), DBQ (SSOP, 24), PW (TSSOP, 24), DGV (TVSOP, 24), and RHL (VQFN, 24).
