Some applications require multiple linear Hall sensors to detect position in different parts of the system. In those cases, the primary challenge would be the availability of multiple ADC that are required to digitize the information from the sensors. In cases where the sensor is placed remotely away from the microcontroller, this would also mean multiple output lines between the sensor and microcontroller.

With the ability to place the output in high-impedance state during shutdown mode, multiple TMAG5253s can share the analog output. This can minimize the system cost by using a single ADC. Figure 9-1 shows two devices that share the same analog output, with their respective EN pins controlled by the microcontroller. A pulldown resistor can be used to pull the output to ground when both the devices are placed in shutdown mode.

Figure 9-1 Multiple Sensors With Shared Output

Figure 9-2 Timing Diagram for Multiplexing the Sensor Outputs

Figure 9-2 shows how the GPIOs of the microcontroller can be used to multiplex the outputs from the two sensors. When the GPIO1 goes high, Device 1 is enabled and drives the output line to the corresponding output after the power-on time. During this time, GPIO2 is driven low and Device 2 is placed in shutdown mode. When the output from the second device has to be measured, the first device must be turned off before the second device is enabled, indicated by t_mux in the timing diagram. B₁ and B₂ correspond to the magnetic fields seen by Device 1 and Device 2, respectively.

With the ability to support up to 1-nF capacitive loads, the TMAG5253 enables multiple sensors to be connected to the same output. If the load capacitance on each sensor is about 20 pF, this would translate up to the ability of 50 sensors sharing the same output.