NOVOSENSE Provides A One-stop Solution for Power Drive and Signal Sampling in Electronic Control Systems

PublishTime： 2023-06-29 Article Source：NOVOSENSE News

The electrification trend has doubled the number of vehicle semiconductors, and intellectualization will increase this number exponentially. Power semiconductors, compared to sensors and MCUS, have increased significantly: from 21% to 55%. Therefore, it has become an urgent need to develop a domestic solution for the automotive-qualified power semiconductor and break the technology monopoly.

NOVOSENSE third-generation driver adapts to the 800V platform, and supports parallel connection of multiple silicon carbide tubes, with peak power of 200-300kW.

For electric drivers and new energy assembly, NOVOSENSE provides four categories of products, namely, sensors, signal chain, isolation, and interface, as well as power and driver. In the future, NOVOSENSE will further increase its applications in electric drivers, and develop integrated driver solutions specifically for the third-generation semiconductor and high-performance and high-power IGBT. These are the four major product types of NOVOSENSE for new energy assembly. The technical basis behind these products is derived from the isolation technology self-developed by NOVOSENSE in 2017.

Core isolation technology of NOVOSENSE Microelectronics

NOVOSENSE has developed a full set of high-performance analog chip solutions that can cover all electric drivers, and it is also the first company in China to provide global automotive-qualified solutions, especially isolation drivers, current sampling, and isolation sampling based on isolation solutions.

All isolation products of NOVOSENSE are a multistage isolation band solution in the structure. CMOS technology is used in the original secondary side, and CMOS BCD is used to develop certain conditioning and demodulation circuits. At both ends of the barrier are layers of silica about 30 microns thick to form capacitors. Since capacitors are naturally used to isolate DC and connect AC when a signal is needed to transmit the capacitor, a conditioning circuit is built at the transmitting end to transmit the signal to the negative end using OOK modulation mode. A silica layer is also made in the back, which also forms a capacitor layer. You can see the capacitance values of the capacitors at both ends in the product specification, and the high and low screen signals can be transmitted from the primary side to the secondary side through signal transmission.

The advantage of using two layers of capacitors is that if a short circuit occurs on either the primary or secondary side, the high voltage signal of this short circuit can be independently transmitted from the secondary side to the primary side without causing any injury or damage to the human body or the communication low voltage domain respectively.

These are the principles for implementing the isolation strip. Next, we will introduce the technical specifications. The first is the isolation layer medium, and NOVOSENSE adopts silica for it. The silica can withstand a voltage of up to 500 volts per micron, while NOVOSENSE single-capacitor isolation layer is 30 microns thick and can withstand a voltage of more than 1,000 volts.

End customers often ask how much operating voltage a chip can withstand. This requires the introduction of a specific indicator parameter: the I/O repeatable operating voltage. Before the ex-factory, NOVOSENSE tests the isolation voltage of all chips.

In addition to these parameters, another question is: how to ensure that the isolation strip of mass products meets these basic parameters?

In fact, there is a German VDE 0884-11 certification index in the industry, and the TDDB data analysis based on industry safety specifications is mentioned in the test. It is important to note that once a chip has passed the TDBB test, it means that the lifetime failure rate of the chip is less than 1 PPM. If the chip specification indicates an isolation voltage of 1000 volts, this test can guarantee that the chip has a failure rate of 1 PPM over 37.5 years of continuous high voltage.

At present, all NOVOSENSE isolation chips have passed the VDE certification.

Driver technology of NOVOSENSE Microelectronics

NOVOSENSE provides two generations of isolation drivers. The first generation is a simple isolation driver, which is divided into a single tube and double tube; the terminal power device can be IGBT and SiC, which is compatible with voltage-type input and current-type input, that is, compatible with the traditional optocoupler driver solution.

To support high-frequency switching in digital power and OBC applications, NOVOSENSE keeps chip input/output delay and matches between different channels below 100 nanoseconds to support chopper frequencies of 100-200K Hz. Peak current is up to 4-5A to support products of 11 kW to tens of kilowatts.

In 2021, NOVOSENSE introduced the second-generation ISO Smart Driver, which increases the peak drive current to 10A. This product also supports IGBT modules and silicon carbide modules, enabling terminal Tier 1 to apply chips to a wider range of scenarios. In the future, it will develop third-generation products to support high voltage platforms of 800 volts, parallel connection of multiple silicon carbide tubes, greater electric drive power, and peak power of up to 200-300kW.

In terms of protection function, the second-generation product has integrated over-saturation soft shutdown protection into the chip, which is of great help to the functional security of the next-generation products.

Current sampling-related products of NOVOSENSE Microelectronics

Current sampling products are also very important. If viewed from the whole system, the electric driver involves the overvoltage protection and monitoring of the bus voltage, and the magnetic sensor is used to detect the current. At present, NOVOSENSE is the only domestic supplier that can provide both isolated operational amplifier sampling mode and magnetic current sampling mode.

In the field of magnetic current detection, NOVOSENSE provides two solutions, currently the most used one in China is the magnetic ring: It conducts the current to the motor through Busbar, and a magnetic ring is added to lock all the magnetic fields on it. By monitoring the changes in the magnetic field on the magnetic ring, the current can be monitored. Another solution is to directly dig a slot in the Busbar and make a plane magnetic field to realize current monitoring.

In terms of sampling, it also provides two generations of products. The first generation of products mainly includes isolated voltage sampling and isolated current sampling chips. At the voltage sampling end, 1311 series solutions are provided, which can realize the functions of overvoltage protection and bus voltage monitoring by detecting single terminal voltage.

The business of NOVOSENSE covers front-end design, packaging of onboard wafers, reliability testing, and mass production. All aspects are designed, manufactured, and tested in strict accordance with the requirements of automotive-qualified specifications, which can meet the requirements of customers in the whole process.

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