SBOS820A September 2019 – June 2020 TMCS1100
The TMCS1100 can be configured to allow for bidirectional or unidirectional measurable current ranges based on the external voltage on the VREF pin. The output voltage is limited by VOUT swing to either supply or ground. Linear output swing range to both VS and GND is calculated by equations Equation 16 and Equation 17.
Rearranging the transfer function of the device to solve for input current, and substituting VOUT,max and VOUT,min yields the maximum and minimum measurable input current ranges as shown in Equation 18 and Equation 19.
Setting VREF to the middle of the output swing range provides bidirectional measurement capability, whereas setting VREF close to the ground provides a unidirectional measurement. Custom ranges with nonuniform positive and negative input current ranges can be achieved by appropriately scaling the VREF potential relative to the full output voltage range.