SCEA134 Application brief

Functional Block Diagram

For the purpose of this application brief, Figure 1 shows logic and translation use cases. Each red block is associated to a use-case document. Table 1 and Table 2 list documentation links. For a complete block diagram, see the Mechanically Scanning LIDAR product page.

Figure 1 Simplified Block Diagram for Mechanically Scanning LIDAR

Logic and Translation Use Cases

Each use case is linked to a separate short 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 Figure 1 .

Table 1 Logic Use Cases

Nearest Block	Use-Case Identifier	Use Case
Battery input protection	Power good combination	Combine Power Good Signals
Digital processing	I/O expansion	Increase Inputs on a uC
Digital processing	Timed restart	Reset a System for a Short Time
Diagnostics and monitoring	Combine error signals	Use Fewer Inputs to Monitor Error Signals

Table 2 Translation Use Cases

Nearest Block	Use-Case Identifier	Use Case
Digital processing	UART translation	Translate Voltages for UART
Light sensor	I2C translation	Translate Voltages for I2C

Combining Error Signals

Error source signals can be combined to reduce the number of required inputs to a system controller when it is more important to know that an error has occurred than it is to know which device triggered the error. For example, if an overheating condition is detected, it is likely that the system can increase fan speed or shut down operations to respond to the issue regardless of which device signaled the error.

Example Block Diagram for Combining Three Error Sources Into One Error Signal Using OR Gates

See the Use Fewer Inputs to Monitor Error Signals video to learn more about this use case.

Table 3 Recommended Parts

Part Number	Automotive Qualified	V_CC Range	Type	Features
SN74HCS21-Q1	✓	2 V – 6 V	Dual 4-input AND gate	Schmitt trigger inputs Positive and negative clamp diodes on all inputs and outputs
SN74LVC1G125-Q1	✓	1.65 V – 5.5 V	Single buffer with 3-state outputs	Standard CMOS inputs Inverting OE signal; see '1G126 for non-inverting OE signal
SN74LVC1G11-Q1	✓	1.65 V – 5.5 V	Single 3-input AND gate	Standard CMOS inputs Supports partial-power-down with I_off circuitry, disabling outputs.
SN74LVC1G96-Q1	✓	1.65 V – 5.5 V	Configurable multi-function gate	Schmitt trigger inputs Between the '1G57 and '1G58, all 2-input logic gate functions can be produced. See data sheets for details.

For more devices with Schmitt trigger input architecture, see the online parametric tool which can be sorted by the desired voltage, output current, and other features.