With more and more electronic devices in automobiles, all of these electronic devices require in-vehicle networks (IVNs) for transmission and data collection. This article will show you the characteristics of two mainstream IVN technologies, i.e. controller area network (CAN) and local interconnect network (LIN), as well as the transceiver solution introduced by onsemi. Electronic automotive devices need IVNs to transmit and collect data.
As progressively more active safety systems, such as anti-locking breaking systems (ABS), traction control systems (TRC), electronic brake-force distribution (EBD), and brake assist systems (BAS), become increasingly mature, together with more advanced safety technologies, such as lane-keeping assistant (LKA), forward-collision warning (FCW), adaptive cruise control (ACC), blind-spot warning (BSW), automatic emergency braking (AEB) and so on, more and more electronic devices are equipped in the vehicle. These electronic devices and central control systems need various IVNs to transmit and collect relevant vehicle driving data.
CAN and LIN are the mainstream technologies most commonly used in IVNs
At present, common IVNs include CAN, LIN, FlexRay, MOST, SENT, etc, among which, CAN and LIN are the most commonly used mainstream technologies.
CAN is a bus standard for vehicles with diverse features. It is designed to allow single chips and instruments on the network to communicate with each other without the need for a host. It is based on the information transmission protocol. At the beginning of the design, multi-task multiplexed communication cables were used on vehicles to reduce the usage of copper wires. CAN has good flexible adjustment capability and can add nodes to the existing network without making adjustments in software and hardware. In addition, the transmission of information is not based on special types of nodes, which increases the convenience of upgrading the network.
The LIN bus is designed to transfer low-speed data from the control devices at the lowest possible cost, with an aim to eliminate as much wiring as possible and is implemented using a single wire in each node. Each node has a slave MCU state machine that identifies and transforms instructions specific to the feature. The main attraction of the LIN bus is that not all features are time-tight and are usually related to passenger comfort. LIN is typically used in rearview mirrors, glass lifters, door switches, door locks, vehicle seats, engine sensors, engine cooling fans, wiper controls, rain sensors, light controls, sunroofs, etc.
onsemi has introduced a number of transceivers for CAN and LIN applications. This article will show you several of them for your reference.
High-speed low-power CAN and CAN FD transceivers
The NCV7344 CAN transceiver is the interface between a CAN protocol controller and its physical bus. The transceiver provides differential transmit capability to the bus and differential receive capability to the CAN controller. The NCV7344 guarantees additional timing parameters to ensure robust communication at data rates beyond 1 Mbps to meet CAN's flexible data rate requirements (CAN FD). These features make the NCV7344 an ideal choice for all types of HS-CAN networks among nodes that need low power mode with wake-up capability through a CAN bus.
The NCV7344 is compatible with ISO 11898−2:2016, in accordance with up to 5 Mbps loop delay symmetry specifications. The VIO pin on the NCV7344-3 allows direct interfacing with 3 V to 5 V microcontrollers, supporting a very low current standby mode that can wake up via the bus, with low electromagnetic radiation (EME) and high electromagnetic immunity, and without a common mode (CM) choke. A bus with an un−powered node will not be disturbed, having the transmit data (TxD) dominant timeout function. The behavior of the chip is predictable under all supply conditions. The bus pins have extremely high ESD robustness, which can resist system ESD pulses greater than 8 kV, support thermal protection, short-circuit proof of bus pins to the supply voltage and ground. There are bus pins that can protected against transients in the automotive environment and are all Pb-free devices. With wettable flank packages, they can be used to enhance optical inspection, and conform to AEC-Q100 and PPAP standards. They are typically used in automotive, industrial networks, and other fields.
High-speed low-power dual CAN FD transceivers
The NCV7446 is a dual CAN FD physical layer transceiver, which allows the interfacing of two independent CAN physical buses and two independent CAN protocol controllers. It consists of two completely stand-alone NCV7344 transceivers, and the NCV7446 guarantees additional timing parameters to ensure robust communication at data rates beyond 1 Mbps to meet CAN's flexible data rate requirements (CAN FD). These features make the NCV7446 an ideal choice for all types of HS-CAN networks among nodes that need low power mode with wake-up capability implemented via the CAN bus.
The NCV7446 is compliant with the ISO 11898−2:2016 specification, with specified CAN FD timing up to 5 Mbps. It has a very low current standby mode that wakes up via the bus, with low EME and high electromagnetic immunity. A bus with an un-powered node will not be disturbed, supporting the transmit data (TxD) dominant timeout function. The behavior of the chip is predictable under all supply conditions. The bus pins have high ESD robustness, support thermal protection, short-circuit proof of bus pins to the supply voltage and the ground. There are bus pins that can prevent transients in the automotive environment. With wettable flank packages, they can be used to enhance optical inspection, and conform to AEC-Q100 and PPAP standards. The device is Pb-free, halogen-free/brominated flame retardant-free, and RoHS compliant.
High-speed low-power CAN transceivers
The NCV7342 CAN transceiver is the interface between the CAN protocol controller and the physical bus and can be used in 12 V and 24 V systems. Due to the wide common-mode voltage range of the receiver input and other design features, the NCV7342 can achieve excellent EMS levels. In addition, extremely low EME can be achieved through excellent matching of the output signals.
The NCV7342 is compatible with ISO 11898−2 and ISO 11898−5 standards and supports high-speed transmission up to 1 Mbps. The VIO pin on the NCV7342-3 allows direct interfacing with 3 V to 5 V microcontrollers, while the VSPLIT pin on the NCV7342-0 can be used for bus common-mode stabilization. When waking up via the bus, current consumption in standby mode is extremely low, with excellent EMS levels over full frequency range. With very low EME, there is no common mode choke. Bus pins that prevent system ESD pulses greater than 15 kV support the transmit data (TxD) dominant timeout function and bus dominant timeout feature in standby mode. The behavior of the chip is predictable under all supply conditions. When the node is not powered on, it will not interfere with the bus. Bus pins with thermal protection that can prevent transients in automotive environment can support short-circuit proof of bus pins to the supply voltage and the ground, and are Pb-free devices. With wettable side packages, they can be used to enhance optical inspection, and conform to AEC-Q100 and PPAP standards.
High-speed CAN and CAN FD transceivers
The NCV7351 CAN transceiver is the interface between the CAN protocol controller and the physical bus and can be used in 12 V and 24 V systems. The NCV7351 complements the CAN high-speed transceiver family and complements the NCV734x CAN stand-alone transceiver and previous products such as AMIS42665, AMIS3066x, etc. The NCV7351F is a complement to the NCV7351-based transceiver family with improved bit timing symmetry to meet the CAN flexible data rate requirements (CAN FD).
Due to the wide common-mode voltage range of the receiver input and other design features, the NCV7351 can achieve excellent EMS levels. In addition, extremely low EME can be achieved through excellent matching of the output signals. The NCV7351 is compatible with the ISO 11898−2 standard and supports high-speed transmission up to 1 Mbps. The NCV7351F version has loop delay symmetry specifications (up to 2 Mbps and up to 5 Mbps according to ISO11898−2, which are for information only). The VIO pin on the NCV7351(F)D13 version allows direct interfacing with 3 V to 5 V microcontrollers, while the EN pin on the NCV7351D1E version allows the transceiver to be switched to a very low current off mode, with excellent EMS levels over the full frequency range, very low EME, and no common-mode choke.
The NCV7351 has bus pins that can prevent system ESD pulses greater than 15 kV, and supports transmit data (TxD) dominant timeout function. The behavior of the chip is predictable under all supply conditions. A bus with an un-power node will not be disturbed, supporting short-circuit proof of bus pins to the supply voltage and the ground, with bus pins and thermal protection functions that can prevent transients in automotive environments. The NCV7351 is Pb-free and complies with AEC-Q100 and PPAP standards.
Full-featured LIN transceivers
The NCV7321 is a full-featured LIN transceiver designed to establish an interface between the LIN protocol controller and the physical bus. The transceiver is implemented by I3T technology, which enables high-voltage analog circuits and digital features to coexist on the same chip.
The NCV7321 LIN bus transceiver is compliant with the specification revision 2.x (backward compatible with version 1.3) and the J2602. It has a bus voltage of 45 V and a transmission rate of 1 kbps to 20 kbps. It supports the K-Line bus architecture. In terms of protection features, it supports thermal shutdown, indefinite short-circuit protection towards the supply and ground on pins LIN and WAKE, and sudden load dump protection (45 V). With bus pins that can prevent transients in automotive environments, it supports integrated slope control in EMI compatibility.
The NCV7321 has three modes of operation, including normal mode, in which the LIN transceiver can be enabled, communication is carried out via the LIN bus, and the INH switch is ON. In sleep mode, the LIN transceiver is disabled, the power consumption of VBB is minimized, and the INH switch is OFF. In standby mode, the transition mode is reached after power-up or wake-up events, and the INH switch is ON. The wake-up feature can bring the component from sleep mode into standby mode via the LIN command or a digital signal on the WAKE pin, such as an external switch.
The NCV7321 conforms to AEC-Q100 and PPAP standards and is Pb-free, halogen/brominated flame retardant-free, and RoHS compliant.
ISO 17987-4 and SAE J2602 compliant LIN transceivers
The NCV7329 is a full-featured LIN transceiver designed to establish an interface between the LIN protocol controller and the physical bus, compliant with ISO 17987−4 (backward compatible with LIN specification revision 2.x and 1.3) and SAE J2602. It has a bus voltage of 42 V and a transmission rate of 1 kbps to 20 kbps. It supports TxD timeout function and integrated slope control. It has protection functions such as thermal shutdown, undervoltage protection, and bus pins to prevent transients in the automotive environment.
The NCV7329 supports three modes. In normal mode, the LIN transceiver is enabled and communicates through the bus. In sleep mode, the LIN transceiver is disabled to minimize the power consumption of VBB. In standby mode, the transition mode is reached after the LIN bus wake-up event is supported.
The NCV7329 supports a subset that is pin-compatible with the NCV7321, is also compatible with the K-line, and complies with AEC-Q100 and PPAP standards. The device is Pb-free, halogen/brominated flame retardant-free, and RoHS compliant.
Dual-channel physical layer device supporting the LIN protocol
The NCV7422 is a dual-channel physical layer device using the LIN protocol, which allows the interfacing of two independent LIN physical buses and LIN protocol controllers. The device complies with ISO 17987-4, LIN 2.2 a, LIN 2.2, LIN 2.1, LIN 2.0, and SAEJ2602.
The NCV7422 is a LIN bus transceiver in a DFN-14 green package (Pb-free). It supports a bus voltage of 42 V and a transmission rate of 1 kbps to 20 kbps, TxD timeout function, integrated slope control, protection functions such as thermal shutdown, undervoltage detection, bus pins to prevent transients in automotive environment mode, etc.
The NCV7422 supports normal mode in which the LIN transceiver is enabled and communicates via the bus, supports sleep mode in which the LIN transceiver is disabled to minimize the power consumption of VBB, and supports standby mode in which the transition mode is reached after the LIN bus wake-up event.
The NCV7422 is pin-compatible with the NCV7329 DFN8 package and also compatible with K-line. With a wettable flank package, it can be used to enhance optical inspection, and conforms to AEC-Q100 and PPAP standards. The device is Pb-free, halogen/brominated flame retardant-free, and RoHS compliant.
Conclusion
With more and more electronic devices installed in automobiles, the operation stability of IVNs is very vital. onsemi offers a variety of transceivers supporting CAN or LIN protocols, which can meet the needs of various electronic automotive devices and is worthy of further understanding and adoption by manufacturers interested in entering the relevant product market.
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