SENSORS TLE4972 is coreless …
More powerful battery systems allow higher peak currents in normal operation and in the event of a short circuit. If the current sensor has a fl ux concentrator with magnetic core material, this must be generously dimensioned accordingly. Otherwise, a short-circuit current could permanently magnetize it, thereby distorting the system’s transfer characteristic (Figure 1). Seeing as the TLE4972 is coreless, saturation of a magnetic core with subsequent remanence does not occur even in the event of overcurrent resulting from a short circuit, for example. This supports high linearity, and hysteresis in the transfer characteristic is avoided.
Measurements for fast overcurrent and short-circuit detection are needed, especially for the main battery switch. This is enabled by the TLE4972 thanks to two independent open-drain outputs with confi gurable trigger thresholds and programmable noise pulse fi lters. They signal overcurrent, e.g. to a microcontroller or gate driver. The typical response time of the over-current detection (OCD) open- drain output pins is less than 1µs. The wide frequency range of the TLE4972 from 0Hz to at least 120kHz contributes to fast overcurrent detection without software- induced latency.
The differential analogue output also provides a high bandwidth and can thus be used for the torque control of drive motors in electric vehicles.
Thanks to the differential measuring method, undesired stray fi elds, e.g. due to the current fl ow in neighbouring conductors, have no impact whatsoever on the
Figure 2: Mounted above or below a copper rail, the TLE4972 is suitable for measuring currents of up to approx. 800A
measurement signal. Additional sensors on the chip also compensate for the effects of temperature and mechanical stress. As a result, the accuracy and stability over the component’s entire service life is increased. The TLE4972 outputs measured values in analogue form. The output can be confi gured as fully differential, semi- differential, or single-ended. For the single-ended output mode, the sensor imports its reference voltage from an external source, e.g. from a connected analogue/digital converter (ADC). In semi- differential mode, it exports its internal Vref to a pin, e.g. for use with a connected ADC. This counteracts common mode noise as long as it is constant throughout the conversion time of the ADC. In fully differential mode, the TLE4972 provides two output signals in phase opposition. This mode of operation in conjunction with an ADC that has differential inputs ensures the best suppression of common mode noise signals along the analogue transmission path. In this respect, the TLE4972 is ideal for Infi neon’s
Figure 3: The two package variants of the TLE4972 offer various mounting options. This makes it suitable for measuring currents from 200 A to 800A
Programmable System on Chip (PSoC) series 4, 5, and 6, since they have 12-bit ADCs with differential inputs and share the supply voltage range of around 3.3V with the sensor.
Two package variants The TLE4972 is available in two package variants: in the TDSO-16, it is suitable for measuring currents of up to about 400A fl owing through tracks on or in a common multilayer board. For higher currents of up to approx. 800A, Infi neon recommends mounting on a specifi cally shaped copper rail (Figure 2 and 3).
For currents of between 400A and 2kA, the TLE4972 in a TSON-6 package is ideal. Measuring 4.5 mm × 3.5 mm, it can also be installed vertically in a power rail cutout. Infi neon supports developments with the TLE4972 through a new simulation tool that is available online via Infi neon’s Collaboration Platform (activation required). Further, the supplier offers four evaluation boards for various measuring ranges: TLE4972 EVAL STD PCB (up to approx. 200 A), TLE4972 EVAL INLAY (up to approx. 400 A), TLE4972 EVAL LAT BAR (up to approx. 580A), and TLE4972 EVAL VER (up to approx. 830A).
The TLE4972 is a component for the potential-free measurement of high bidirectional currents. It additionally signals overcurrent autonomously and meets the requirements of ASIL B as a SEooC. The sensor is, therefore, particularly suitable for motor control. Moreover, it can elegantly implement the electronics for an electronic high-voltage fuse in conjunction with the analogue and digital features of a PSoC.
Rutronik Figure 4: Target applications of the TLE4972 current sensor
www.rutronik.com MARCH 2022 | ELECTRONICS TODAY 31
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