SCLA060 Application brief

Functional Block Diagram

Simplified Block Diagram for Digital Cockpit Processing Unit (DCPU) shows a simplified DCPU to illustrate the logic and translation use cases. Each red block has an associated use-case document; links are provided in Table 1 and Table 2. For a more complete block diagram, see the interactive online end equipment reference diagram for DCPUs.

Simplified Block Diagram for Digital Cockpit Processing Unit

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 to the use cases shown in the provided simplified block diagram.

Table 1 Logic Use Cases

Nearest Block	Use-Case Identifier	Use Case
Processing Unit System Power	Power Good Combination	Combine Power Good Signals
Debug Console	Fault Combination	Use Fewer Inputs to Monitor Error Signals
Logic and Translation	Driving LEDs	Drive Indicator LEDs
Logic and Translation	I/O Expansion	Increase the Number of Outputs on a Microcontroller

Table 2 Translation Use Cases

Nearest Block	Use-Case Identifier	Use Case
VIP MCU	I2C	Translate Voltages for I2C
Logic and Translation	UART	Translate Voltages for UART
Logic and Translation	GPIO	Translate Voltages for GPIO

Reset a System for Short Time

System controllers can use GPIO pins to reset other components if a fault is detected; however, system controllers generally cannot reset themselves or their entire system. By using a monostable multivibrator, the system controller can reset the entire system.

Design Considerations

Either falling-edge or rising-edge trigger configurations can be used for this application. See the data sheet of your selected multivibrator for details.
A pullup or pulldown resistor is required to return the input signal to a valid state once the system controller turns off. The recommended value for this resistor is 10 kΩ.
Retriggerable or non-retriggerable monostable multivibrators can be used for this operation
[FAQ] [H] Monostable Multivibrators - Top Questions Answered
[FAQ] How does a slow or floating input affect a CMOS device?
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Table 3 Recommended Parts

Part Number	AEC-Q100	V_CC Range	Function	Features
SN74LVC1G123		1.65 V – 5.5 V	Single-channel multivibrator	Retriggerable, Schmitt-trigger inputs
SN74LV123A		2 V – 5.5 V	Dual-channel multivibrator	Retriggerable, Schmitt-trigger inputs, inverted output
SN74LV123A-Q1	✓	2 V – 5.5 V	Dual-channel multivibrator	Retriggerable, Schmitt-trigger inputs, inverted output
SN74LV221A		2 V – 5.5 V	Dual-channel multivibrator	Schmitt-trigger inputs, inverted output
SN74LV221A-Q1	✓	2 V – 5.5 V	Dual-channel multivibrator	Schmitt-trigger inputs, inverted output
SN74AHC1G04		2 V – 5.5 V	Single-channel inverting buffer
SN74AHC1G04-Q1	✓	2 V – 5.5 V	Single-channel inverting buffer

For more devices, browse through the online parametric tool which allows users to sort by desired voltage, channel numbers, and other features.