SBOS825D September 2019 – July 2021 TMCS1101
The TMCS1101 only requires a power supply (VS) on the low-voltage isolated side, which powers the analog circuitry independent of the isolated current input. VS determines the full-scale output range of the analog output VOUT, and can be supplied with any voltage between 3 V and 5.5 V. The TMCS1101 zero-current output voltage is derived from verses using a resistor divider; therefore, take care to optimize the power supply path for both noise and stability across temperature to provide the highest precision measurement. To filter noise in the power-supply path, place a low-ESR decoupling capacitor of 0.1 µF between VS and GND pins as close as possible to the supply and ground pins of the device. To compensate for noisy or high-impedance power supplies, add more decoupling capacitance.
The TMCS1101 power supply VS can be sequenced independently of current flowing through the input. However, there is a typical 25-ms delay between VS reaching the recommended operating voltage and the analog output being valid. Within this delay VOUT transfers from a high impedance state to the active drive state, during which time the output voltage could transition between GND and VS. If this behavior must be avoided, a stable supply voltage to VS should be provided for longer than 25 ms prior to applying input current.