NXP NVT2008BQ,115: A Comprehensive Technical Overview and Application Note
The NXP NVT2008BQ,115 is a highly integrated, 8-bit I²C-bus controlled level translator designed to interface between low-voltage and higher-voltage systems. As a cornerstone component in mixed-voltage logic designs, it provides a robust and flexible solution for ensuring seamless communication between devices operating at different supply voltages. This device is particularly critical in modern electronic systems where processors, sensors, and peripherals often operate at diverse voltage levels, ranging from 1.2 V to 5.5 V.
Technical Overview
The NVT2008BQ belongs to a family of bidirectional voltage-level translators. Its core function is to provide bidirectional voltage translation for eight channels without the need for a direction control pin. The translation is achieved through an automatic direction-sensing circuit, which significantly simplifies the design-in process.
Key specifications include:
Voltage Translation Range: The VREF1 port supports a voltage range from 1.2 V to 5.5 V, while the VREF2 port supports a range from 1.8 V to 5.5 V. This wide range allows it to bridge nearly all common logic levels, including 1.8 V, 2.5 V, 3.3 V, and 5.0 V.
I²C-bus Compatibility: The device is fully compliant with the I²C-bus standard and is capable of operating in both Standard-mode (up to 100 kHz) and Fast-mode (up to 400 kHz). Its architecture ensures that the low-level input voltage (VIL) is lower than the low-level output voltage (VOL), preventing negative voltage spikes on the I²C bus lines.
High Noise Immunity: The NVT2008BQ features high noise immunity on the control pins, which is essential for maintaining signal integrity in electrically noisy environments, such as automotive or industrial applications.
Packaging: The part number suffix '115' denotes a specific packaging option. The NVT2008BQ,115 is supplied in a DHVQFN20 (3.5 x 4.5 mm) package, offering a compact footprint suitable for space-constrained PCB designs.
Application Notes
The primary application for the NVT2008BQ is in I²C-bus and SMBus voltage level shifting. It is ideal for use in a wide array of products, including:
Servers, Motherboards, and Networking Equipment: To enable communication between a low-voltage CPU and higher-voltage peripheral chips or sensor hubs.
Telecommunications Systems: For interfacing cards and modules that operate at different power domains.
Industrial Automation and Automotive Systems: Where reliability and the ability to function across a wide temperature range are paramount. The device's robustness makes it suitable for translating levels for sensors, EEPROMs, and other I²C-controlled devices in harsh environments.
Design Considerations:
1. Power Supply Sequencing: While not always critical, it is generally good practice to apply the VREF power supplies before or simultaneously with the I/O signals to ensure proper initialization of the internal circuitry.
2. Pull-up Resistors: The I²C-bus lines (SCL and SDA) are open-drain. Therefore, external pull-up resistors must be used on both sides of the translator (VREF1 and VREF2). The value of these resistors must be chosen based on the total bus capacitance and the desired speed, following standard I²C design guidelines.
3. Bus Capacitance: The translator effectively isolates the capacitance of the two bus segments. This allows for a higher total allowable bus capacitance, enabling more devices to be connected to the bus or the use of longer traces.
ICGOOODFIND: The NXP NVT2008BQ,115 is an essential component for modern system design, elegantly solving the common challenge of mixed-voltage interoperability. Its bidirectional, automatic operation, combined with a wide voltage range and robust construction, makes it a versatile and reliable choice for engineers. Its integration simplifies PCB layout, reduces component count, and enhances overall system reliability across computing, communication, and industrial applications.
Keywords:
Level Translator
I²C-bus
Bidirectional
Voltage Translation
NXP Semiconductors
