JAJSJW1A October 2020 – August 2021 TMAG5123-Q1
PRODUCTION DATA
The Basic Hall-effect sensor consists of four terminals where a current is injected through two opposite terminals and a voltage is measured through the other opposite terminals. The voltage measured is proportional to the current injected and the magnetic field measured. By knowing the current inject, the device can then know the magnetic field strength. The problem is that the voltage generated is small in amplitude while the offset voltage generated is more significant. To create a precise sensor, the offset voltage must be minimized.
Chopper stabilization is one way to significantly minimize this offset. It is achieved by "spinning" the sensor and sequentially applying the bias current and measuring the voltage for each pair of terminals. This means that a measurement is completed once the spinning cycle is completed. The full cycle is completed after sixteen measurements. The output of the sensor is connected to an amplifier and an integrator that will accumulate and filter out a voltage proportional to the magnetic field present. Finally, a comparator will switch the output if the voltage reaches either the BOP or BRP threshold (depending on which state the output voltage was previously in).
The frequency of each individual measurement is referred as the Chopping frequency, or fCHOP. The total conversion time is referred as the Propagation delay time, tPD, and is basically equal to 16/fCHOP. Finally, the Signal bandwidth, fBW, represents the maximum value of the magnetic field frequency, and is equal to (fCHOP/16)/2 as defined by the sampling theorem.