SCLA050 November   2021 SN74HCS08


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Functional Block Diagram

Simplified Block Diagram for Single Board Computers shows a simplified single board computer block diagram to illustrate the logic and translation use cases. Each red block has an associated use-case document. Links are provided in Table 1-1 and Table 1-2. For a more complete block diagram, see the interactive online end equipment reference diagram for single board computers.

Figure 1-1 Simplified Block Diagram for Single Board Computers

Logic and Translation Use Cases

Each use case links to a separate document that provides additional details including a block diagram, design tips, and part recommendations. The nearest block and use-case identifiers are listed to match up exactly to the use cases shown in the provided simplified block diagram.

Table 1-1 Logic Use Cases
Nearest Block Use-Case Identifier Use Case
Point-of-Load Regulators Power Good Combination Combine Power Good Signals
Housekeeping Fault Combination Use Fewer Inputs to Monitor Error Signals
User Interface Indicator LED Drive Indicator LEDs
Output Expansion Increase the Number of Outputs on a Microcontroller
Clocking Buffer Redrive Digital Signals
Table 1-2 Translation Use Cases
Nearest Block Use-Case Identifier Use Case
Network Interface RGMII Translate Voltages for RGMII
MDIO Translate Voltages for MDIO
Input/Output Interface SPI Translate Voltages for SPI
I2C Voltage Translation for I2C Interface Modules
GPIO Translate Voltages for GPIO

Voltage Translation for I2C Interface Modules

It is common to see single board computers providing at least one I2C interface to connect external sensors or other modules. These external components can operate at a different voltage than the primary system controller. The addition of a voltage level translator protects low-power system controllers and ensures accurate communication to the peripheral module.

GUID-9018E38E-A3C2-429F-B7AB-580152E96182-low.gif Figure 1-2 Example I2C Voltage Translation Block Diagram
  • Typically operates at 100 kbps, 400 kbps, or 3.4 Mbps
  • Requires auto-bidirectional, open-drain compatible voltage translators
  • Translators enable communication when devices have mismatched logic voltage levels
  • Prevents damage to devices that cannot support higher voltage inputs
  • Improves data rates and signal integrity over discrete translation solutions
  • Protects controller while peripheral is not connected
  • Need additional assistance? Ask our engineers a question on the TI E2E™ Logic Support Forum
Table 1-3 Recommended Parts
Part Number Automotive Qualified Voltage Translation Range Features
LSF0102-Q1 0.95 V to 5.5 V
0.95 V to 5.5 V
Auto-bidirectional with open-drain support
Flexible design with external pull-up resistors
See Understanding the LSF family of bidirectional, multi-voltage level translators for detailed design instructions
TXS0102-Q1 1.65 V to 3.6 V
2.3 V to 5.5 V
Auto-bidirectional with open-drain support
One-shot edge accelerators improve signal integrity
Internal 10-kΩ pull-up resistors reduce external component count
TXS0102 1.2 V to 3.6 V
1.65 V to 5.5 V

For more I2C translation devices, browse through the online parametric tool where you can sort by desired voltage, channel numbers, and other features.