SBOS820A September 2019 – June 2020 TMCS1100
The reference voltage provided externally to the TMCS1100 on the VREF pin determines the zero current output voltage, VOUT,0A. This zero-current output level along with sensitivity determine the measurable input current range of the device, and allows for unidirectional or bidirectional sensing, as described in the Absolute Maximum Ratings table. Figure 46 illustrates the transfer function of the TMCS1100A2 with varying VREF voltages of 0 V, 1.25 V, and 2.5 V. By shifting the zero current output voltage of the device, the dynamic range of measurable input current can be modified.
The input voltage on this pin can be provided by any external voltage source or potential, such as a discrete precision reference, a voltage divider, ADC reference, or ground. The VREF pin is sampled by the internal circuitry at approximately 1 MHz, then buffered and provided to the signal chain of the device. An apparent dc load of approximately 1 µA will be observed by the external reference. To prevent errors due to sampling settling, keep the source impedance below the level specified in Electrical Characteristics.