SLYA065 October 2022 TMAG5328
Most Hall-effect switches have a fixed BOP, which typically imposes design constraints on the placement and specifications of the magnet needed to ensure switching of the Hall-effect sensor at the desired distance. To allow design flexibility, many Hall-effect switches come with multiple device variants with different BOP values; however, there are only a finite number of BOP options available with a Hall-effect switch, which still puts constraints on the placement and specifications of the magnet.
The TMAG5328 Hall-effect switch, on the other hand, has an adjustable BOP that can be programmed anywhere between 2 to 15 mT by applying a voltage or connecting a resistor to the ADJ pin of the device. By following simple formulas, it is easy to calculate what resistor value or voltage value is needed to set up the right BOP value. The hysteresis value of the TMAG5328 is fixed to 1 mT, which results in the BRP value being BOP – 1 mT. As an example, if the BOP is set to 5 mT, the BRP would be set to 4 mT.
To set the BOP of the TMAG5328 using an external resistor, connect the resistor between the ADJ and GND pins of the device. Figure 1-4 shows the relationship between BOP and resistance defined as BOP(mT) = RADJ(k?). The BOP of the TMAG5328 must be set to a value between 2 mT and 15 mT, RADJ must be set between 2 k? and 15 k?.
The other method to setup the BOP is to apply a voltage to the ADJ pin. The relationship between BOP and voltage is defined as BOP(mT)= VADJ(mV) × 0.0125. To apply a voltage on the ADJ pin, the voltage source must be able to settle within 4 μs after being exposed to a 80-μA current on the ADJ pin. Figure 1-5 shows that the TMAG5328 BOP must be set to a value between 2 mT and 15 mT and the VADJ must be set between 160 mV and 1200 mV.