NVE Isoapps-CAN

Isolated Controller Area Network (CAN)

In today's CAN networks, node-to-node isolation is increasingly recommended by designers to reduce EMI susceptibility, especially in high-speed applications. The speed of IsoLoop Isolators minimizes CAN loop delay to maximize data rate over any given bus length. NVE offers single-chip isolated CAN transceivers and bidirectional isolators for use with stand-alone CAN transceivers.

Illustrative applications are as follows:

Isolated CAN Transceiver Reference Design

IL41050xxx Isolated CAN Transceiver Reference Design

IL41050xxx single-chip isolated CAN transceivers provide isolated CAN interfaces in a single chip. The isolators operate on the 3.3 V microcontroller power supply, and the dc-dc convertor provides 5 V to power the bus side. The IL41050TA can withstand 150 V transients on the bus. Varistors on the bus provide additional ESD protection if necessary.

Designed for harsh CAN and DeviceNet environments, IL41050xxx transceivers have a -55 to +125 C operating range, transmit data dominant time-out, bus pin transient protection, thermal shutdown protection, and short-circuit protection. Unique edge-triggered inputs improve noise performance.

An innovative non-volatile programmable power-up feature prevents unstable nodes. A state that needs to be present at node power up can be programmed at the last power down. For example if a CAN node is required to pulse dominant at power up, TxD can be sent low by the controller immediately prior to power down. When power is resumed, the node will immediately go dominant allowing self-check code in the microcontroller to verify node operation. If desired, the node can also power up silently by presetting the TxD line high at power down. At the next power on, the IL41050xxx will remain silent, awaiting a dominant state from the bus.

Isolating Standard CAN Transceivers

Isolated CAN with IL712 Isolator

This simple circuit works with any CAN transceiver with a TxD dominant timeout, which includes all of the current-generation transceivers including the AMIS-30660 or the Philips/NXP TJA1050. Propagation delay is critical for CANbus, and the IL712 and IL721 bidirectional isolators have best-in-class propagation delay of 10 ns typical. This minimizes CAN loop delay and maximizes data rate over any given bus length, making IsoLoop Isolators ideal for CAN isolation. NVE also offers the smallest two-channel isolator, the IL712-1, in a unique MSOP-8.

Isolating Legacy CAN Transceivers

Isolated Legacy CAN Transceiver