Does your design have a low talker?

Other Parts Discussed in Post: SN74AXC8T245, SN74AXC1T45

Many of you can relate to having a conversation with a “low talker” – someone whose ultra-low voice makes them difficult to understand. Communicating with a low talker often leads to miscommunication and mixed signals, illustrated to great effect in a well-known sitcom from the 1990s.

So what does a low talker have to do with electronic systems and their designs? Modern electronic signal chains are starting to incorporate more integrated circuits (ICs) that operate at lower voltage nodes. Sub-1V devices such as large microprocessors, field-programmable gate arrays (FPGAs), low-power communication devices and sensors are just a few of the types of devices that are moving to sub-1V levels in order to reduce power and extend battery life. Lower voltages for these devices also means that their input/output (I/O) data interfaces need to operate at lower voltages. In effect, these new low-voltage signal-chain devices are becoming the system’s low talkers.

Just as it can be frustrating to understand low talkers, device-level low talkers present a problem to other devices in the system’s signal chain. The data interfaces of low-voltage devices may not be able to interoperate with higher-voltage devices, resulting in data-signaling issues that you will need to address for proper system operation.

The solution is a voltage level translator that can understand low-voltage devices and translate the data to higher-voltage devices. The concept of I/O level translation has been around for quite some time, with engineers using both discrete as well as integrated IC-based solutions to implement level-translation schemes. Using discrete level-translation solutions to shift between a low talker device I/O and a higher I/O voltage device requires multiple components such as transistors and resistors, carefully selected to ensure proper operation over temperature.

As voltages move lower, discrete approaches are likely to take more engineering effort while remaining inflexible to system voltage variations. Integrated level-translation solutions (IC devices) have been available for quite some time to support level translation for devices operating between 1.2V and 5.5V and provide the flexibility system designers need. However, the older generation of integrated level translators will not be able to support the needs of systems based on new ultra-low-voltage processors, FPGAs, microcontrollers (MCUs) and sensors that have an I/O voltage <1V.

As market necessities such as longer battery life and energy efficiency drive system component voltages lower, a new class of integrated level-translation solutions will be necessary to communicate with a system’s low talkers. Building on our large portfolio of level-translation solutions and long history of logic development, TI is helping system designers overcome the challenges associated with decreasing I/O voltages. Our latest direction-controlled voltage level-translation devices enable system designers to support I/O voltages of <0.80V.

The SN74AXC8T245, an 8-bit direction-controlled voltage translator, and the SN74AXC1T45, a 1-bit direction-controlled voltage translator,  are the first devices in a new family of voltage translators developed to enable designers to implement robust next-generation low voltage interfaces within their systems.   Both the SN74AXC8T245 and SN74AXC1T45 are available in multiple package options making them suitable for many different application spaces.

Figure 1: Example of low-voltage level translation

This new family can help solve low-voltage level-translation problems often encountered by design engineers. For example, low-voltage translation often means that you have to compromise on the amount of current drive that you can expect from the level translator. The new family of devices are compliant to the Joint Electron Devices Engineering Council (JEDEC) 0.7V standard (JESD8-14A.01), which means that these level translators will source enough current to meet common I/O standards, unlike most level-translation devices in the industry.

In addition, the new voltage translators consume much lower power than competing level-translation devices available today. For example, the SN74AXC1T45 will have 60% lower power dissipation than competing devices on a per bit basis, which is extremely beneficial for battery-operated and power-sensitive applications.

System designers are likely to see low talker devices in their designs more frequently in the coming years as system voltages move lower. When you encounter low talker devices in your designs, avoid embarrassing design issues by using level-translation solutions designed to put low talkers in their place.

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