Overview
The SN74LVC8T245DBQR, produced by Texas Instruments, is an 8-bit non-inverting bus transceiver designed for bidirectional voltage level translation. This device features configurable dual power supply rails, allowing each port to operate over a wide voltage range from 1.65 V to 5.5 V. It is optimized for asynchronous communication between two data buses and supports various voltage nodes such as 1.8 V, 2.5 V, 3.3 V, and 5 V. The SN74LVC8T245DBQR is particularly useful in level-translation applications where devices or systems operate at different interface voltages.
Key Specifications
| Parameter | Description | Values |
|---|---|---|
| VCCA and VCCB | Supply voltage range for A and B ports | 1.65 V to 5.5 V |
| Operating Temperature | Free-air temperature range | -40°C to 85°C |
| 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) |
| Input Transition Rate | Maximum input transition rise or fall rate | 20 ns/V (1.65 V to 1.95 V), 20 ns/V (2.3 V to 2.7 V), 10 ns/V (3 V to 3.6 V), 5 ns/V (4.5 V to 5.5 V) |
| ESD Protection | Human-Body Model, Machine Model, Charged-Device Model | 4000 V, 100 V, 1000 V respectively |
| Package Options | Available package types | DBV (SSOP, 24), DBQ (SSOP, 24), PW (TSSOP, 24), DGV (TVSOP, 24), RHL (VQFN, 24) |
Key Features
- Configurable Voltage Translation: Allows bidirectional voltage level translation between any of the 1.8-V, 2.5-V, 3.3-V, and 5-V voltage nodes.
- Dual-Rail Design: Each port can 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.
- 3-State Outputs: Outputs can be placed in a high-impedance state using the output-enable (OE) input.
- ESD Protection: Exceeds JESD 22 standards for Human-Body Model, Machine Model, and Charged-Device Model.
- Latch-Up Performance: Exceeds 100 mA per JESD 78, class II.
- Partial-Power-Down Capability: Ioff circuitry disables outputs to prevent current backflow when powered down.
Applications
- Personal Electronics: Suitable for various personal electronic devices requiring voltage level translation.
- Industrial: Used in industrial applications where different voltage levels are required for communication between devices.
- Enterprise: Applicable in enterprise environments for interfacing devices operating at different voltage levels.
- Telecom: Utilized in telecommunications equipment for voltage level translation between different system components.
The SN74LVC8T245DBQR is particularly useful in any scenario where level-translation between different voltage nodes is necessary.
Q & A
- What is the primary function of the SN74LVC8T245DBQR?
The primary function is to perform bidirectional voltage level translation between two data buses operating at different voltage levels.
- What is the voltage range for VCCA and VCCB?
Both VCCA and VCCB can operate over a voltage range from 1.65 V to 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 outputs. When OE is high, both output ports are in the high-impedance state.
- What are the ESD protection levels for the SN74LVC8T245DBQR?
The device exceeds JESD 22 standards with 4000 V for Human-Body Model, 100 V for Machine Model, and 1000 V for Charged-Device Model.
- How does the VCC isolation feature work?
If either VCC input is at GND, all outputs are placed in the high-impedance state to prevent current backflow.
- What are the available package options for the SN74LVC8T245DBQR?
The device is available in DBV (SSOP, 24), DBQ (SSOP, 24), PW (TSSOP, 24), DGV (TVSOP, 24), and RHL (VQFN, 24) packages.
- What is the maximum output current for the SN74LVC8T245DBQR?
The maximum output current can be up to 32 mA when the device is powered by 5 V.
- How should unused I/Os be handled?
Unused I/Os should be tied to GND to prevent excess ICC and ICCZ and to ensure proper device operation.
- What is the recommended power-up sequence for the SN74LVC8T245DBQR?
It is recommended to first power-up the input supply rail to help avoid internal floating while the output supply rail ramps up. However, both power-supply rails can be ramped up simultaneously.
