SCEA128 April   2023 LSF0102 , SN74AXC4T774 , SN74LXC1T45 , SN74LXC2T45 , SN74LXC8T245 , TXB0104 , TXS0102 , TXU0101 , TXU0102 , TXU0304


  1.   1
  2.   Translate Voltages for SPI
  3.   Design Considerations
  4.   Recommended Parts
  5.   Translate Voltages for UART
  6.   Design Considerations
  7.   Recommended Parts
  8.   Translate Voltages for I2C
  9.   Design Considerations
  10.   Recommended Parts
  11.   Translate Voltages for GPIO
  12.   Design Considerations
  13.   Recommended Parts
  14.   Translate Voltages for SDIO
  15.   Design Considerations
  16.   Recommended Parts
  17.   Translate Voltages for RGMII
  18.   Design Considerations
  19.   Recommended Parts
  20.   Translate Voltages for MDIO
  21.   Design Considerations
  22.   Recommended Parts
  23.   Translate Voltages for a SIM Card
  24.   Design Considerations
  25.   25

The ability to apply machine learning and artificial intelligence algorithms at the edge of computing and electronic system environments is more important today than ever before. Processing videos, images, audio, and other sensor data and then acting on that data at the edge enables higher performance more resilient systems. Bringing processing to the edge is enabling applications to take advantage of technologies such as real-time machine vision, audio transcription, video analytics and many others. One key enabling technology for bringing processing to the edge are System on Modules (SoMs) or Computer of Module (CoMs) Industrial Personal Computers (IPC). SoMs and CoMs are part of a broader category of computing platforms known as single board computers. Systems designers can leverage SoM and CoM modules to implement high performance embedded computing solutions. SoMs are essentially entire computer systems that are built in credit card sized or smaller form factor modules. The small size and low power dissipation of SoMs enables systems designers to bring processing power closer to the edge without having to sacrifice system form factors, processing density, or power budgets. SoMs are extremely popular within industrial applications spaces given the wide selection of SoM and CoM module offerings the market provides. What makes SoMs and CoMs especially versatile is the wide array of system interfaces that are supported by them. The large assortment of I/O (Input/Output) interface types enables SoMs to communicate with many different types of external peripheral devices that are likely to be used in an end application (see Figure 1).

GUID-20230303-SS0I-ZK70-JVXL-RKVDXQBSRLNB-low.png Figure 1 Common SoM and Industrial PC I/O Interfaces

As the core processor devices that make up the SoM move down the silicon process curve, their core voltages also scale downward in order keep power dissipation reasonable while keeping heat dissipation manageable. The lower core voltages of SoM components also limits the I/O voltage that the SoM interfaces can operate at. The lower I/O voltages of new SoMs and CoMs presents a design challenge to design engineers who often need to interface these modules with peripheral devices operating at higher I/O voltages. One solution that system designers can use to resolve I/O level mismatches between SoM and peripheral device I/Os is to use I/O level shifter devices. Integrated I/O level translation solutions are available in a wide assortment of I/O types, bit widths, data rate ranges, current drive capabilities, and package options. Figure 1 shows common interfaces that are supported by mainstream SoMs while Table 1 shows recommended level translation solutions for level shifting between the different SoM and peripheral device I/O types. Texas Instruments’ portfolio of level shifter devices contains many different types of level translation functions that collectively is able to address almost any application requirement. TI’s level translation portfolio includes Auto Directional, Direction Controlled, and Fixed Direction level translators in Industrial, Automotive and Enhanced ratings. The sections below provide level translation recommendations for the most common interface types such as SPI, I2C, and UART. For more information on TI’s level translation devices, see the level translation landing page on

Table 1 Recommended Translator by Interface
Interface Translation Level Small Package Option
Up to 3.6 V Up to 5.5 V
FET Replacement 2N7001T SN74LXC1T45 / TXU0101 DPW, DTQ
1 Bit GPIO/Clock Signal SN74AXC1T45 SN74LXC1T45 / TXU0101 DTQ
2 Bit GPIO SN74AXC2T245 SN74LXC2T45 / TXU0102 DTM
I2C/MDIO/SMBus TXS0102 / LSF0102 TXS0102 / LSF0102 DQE, DQM
4 Bit GPIO SN74AXC4T245 TXB0104 / TXU0104 BQB, DTR
UART SN74AXC4T245 TXB0104 / TXU0204 BQB, DTR
SPI SN74AXC4T774 / TXB0104 TXB0104 / TXU0304 BQB, RUT
JTAG SN74AXC4T774 / TXB0104 TXB0104 / TXU0304 BQB, RUT
I2S/PCM SN74AXC4T774 / TXB0104 TXB0104 / TXU0204 BQB, RUT
Quad-SPI TXB0106 TXB0106 RGY