Intrinsic Safety Design
Ethernet-APL Field Platform Intrinsic Safety Analysis
Introduction
The AD-ETHERNETAPLDEVICE-SL has been certify for Ex ia IIC Ga intrinsic safety requirements according to IEC 60079-11:2011 standard.
Key Parameters
DISCLAIMER
The electrical circuits must be protected by encapsulation within the final device. Such an encapsulation is required for:
protection against spark ignition (IEC 60079-11:2023, 6.6.2.1)
protection against thermal ignition (IEC 60079-11:2023, 6.6.2.2)
rating of electrical components from which the intrinsic safety depends (IEC 60079-11:2023, 6.6.6)
application of separation distances through casting compound (IEC 60079-11:2023, Table 7, column 3)
The corresponding sections of EN 60079-11:2012 shall be applied in addition.
An enclosure is not part of this certification.
The full technical requirements of manufacturer’s specification must be considered for the final device. The local temperature range of -40 °C ≤ Tamb ≤ +85 °C shall never be exceeded. The maximum surface temperature does not exceed 135 °C (for T4), if the end user fulfills all requirements.
This Ex Component has no “Ex” marking as it is not offered separately for sale, but is solely for integration by the Ex Component manufacturer into their own Ex Components or Ex Equipment.
Circuit Analysis
Other than the classical considerations for intrinsic safety component selection, such power ratings, distances or temperature coefficients, special attention has been paid to the blocks highlighted in the diagram.
Surge Protection
Ethernet-APL specifications requires the use of 25A surge protection devices to avoid damage due to high voltage transients. While this requirement is not part of the intrinsic safety certification, it is important to use a low capacitance diodes to minimize the TVS diode capacitance to guarantee proper Ethernet communication.
Common-mode Inductor
The primary function of this inductor is to remove the common mode noise that can be present in the field wiring. The required value exceeds the maximum value for intrinsic safety.
To qualify the component, independent measurements have been performed to verify that the energy stored by the inductor is within allowable limits at different conditions.
LT8440 Sensing and Power Limiter
The LT8440 has been specially designed for Ethernet-APL Intrinsic Safety applications.
It serves two primary functions, the first one is to minimize input current glitches that could disrupt the Ethernet communication, and the second one is to limit the power that can be delivered to the system in case of a fault condition. The LT8440 adjust the maximum current allowable to teh load by sensing the input voltage provided by the field switch so deliver teh maximum possible power to the load.
In our design, the sensing input pins from the LT8440 has been connected after the diode bridge as this allows for a higher capacitance values.
Zener diodes
The Zener diodes will limit the maximum voltage seeing by the circuit in case of failure. Remember that the maximum voltage allowed in the intrinsic safety analysis is 28V.
Certified for intrinsic safety (Ex ia IIC Ga)
Pre-certified Ethernet-APL
Functional safety ready (SIL2) with:
MAX42500 voltage monitor with integrated windowing watchdog
MAX66132 temperature sensor
ADFS7124-4 sigma-delta ADC (SC3 certified)
Complete FMEDA documentation
MAX32690 dual-core MCU (ARM Cortex-M4 with FPU + RISC-V co-processor)
External RAM (512 Mb) and Flash (64 Mb)
MAXQ1065 security co-processor for:
Root-of-trust
Mutual authentication
Data confidentiality and integrity
Secure boot and communications
10BASE-T1L Ethernet via ADIN1110 MAC/PHY
Powered via Single-Pair Power over Ethernet (SPoE), ADIN1100D2Z recommended
Open-source software stack with drivers and example applications
Zephyr RTOS support and integration with Code Fusion Studio
Hardware Design Files
Package Contents
The development kit is delivered with a set of accessories required to put the system together and get it up and running in no time.
This is what you’ll find in the development kit box:
1x AD-EthernetAPLDevice-SL intrinsic safety certify kit (Power and Comms + Digital IS boards)
1x Digital NON-IS board. This board is not IS certify and enables acces to the RISC-V JTAG for debugging pourposes (Digital NON-IS board)
1x MAX32650PICO programmer (ARM) + cable
1x OLIMEX programmer (RISC-V)
1x OLIMEX adapter + cable
Application Development
The AD-ETHERNETAPLDEVICE-SL firmware examples are based on ADI’s open-source no-OS framework. It includes the bare-metal device drivers for all the components in the system as well as example applications enabling connectivity via the 10BASE-T1L interface for system configuration and data transfer.
Additionaly, a propietary PROFINET stack software application is available to enable easy evaluation and system prototyping (https://myanalog.com registration required).
The board is fully supported in Code Fusion Studio {{upcoming}}.
Hardware Components and Connections
Hardware Setup
Required Hardware
Development kit: AD-EthernetAPLDevice-SL
Debugging board: If Risc-V co-processor need to be debugged, replace the IS digital board with the NON-IS Digital board
Power supply: Single-Pair Power over Ethernet (SPoE) via DEMO-ADIN1100D2Z supplied from external power connector (from 9V to 15V), or a Ethernet-APL field switch
ARM programmer: MAX32625PICO or any SWD-compatible programmer
RISC-V programmer Olimex ARM-USB-OCD
Media converter 10BASE-T1L to 10BASE-T or similar. DEMO-ADIN1100D2Z includes a media converter and can be used for both power and data or , or a Ethernet-APL field switch
Setup Instructions
Connect the AD-EthernetAPLDevice-SL to the DEMO-ADIN1100D2Z and ensure all connectors are fully seated.
Connect a 2- or 4-wire PT100 sensor to the temperature connector.
Attach the MAX32625PICO programmer to the ARM debug header using the 10-pin ribbon cable.
For RISC‑V debugging, install the NON‑IS digital board and connect the RISC‑V debug probe to the RISC‑V JTAG header (available only on the NON‑IS board).
Connect the DEMO-ADIN1100D2Z to your PC via Ethernet.
Apply power to the DEMO-ADIN1100D2Z (9V to 15V input). The AD-EthernetAPLDevice-SL will be powered via SPoE.
Software Setup
Programming the AD-EthernetAPLDevice-SL
The AD-EthernetAPLDevice-SL is supported by an open-source software stack based on Analog Devices’ no-OS framework. It includes:
Bare-metal drivers for all on-board components
Example applications for data acquisition and system configuration via 10BASE-T1L
Zephyr RTOS board definition
Integration with Code Fusion Studio
For a complete experience, download latest Code Fusion Studio from here.
The software stack includes:
no-OS drivers and HAL
Example applications for ADCs, DACs, sensors
UART and Ethernet (10BASE-T1L) communication support
Secure boot and authentication via MAXQ1065
Zephyr RTOS support
Help and Support
For questions and more information, please visit the EngineerZone community or contact your local ADI representative.