Furthermore, the digital power monitors can operate with a floating power supply. The respective voltages at each pin on the device are relative to the ground pin potential. Thus, by putting a voltage higher than the system ground on the ground pin, the input of the DPM can accept voltages up to 60 V higher than the device ground pin voltage. The circuit shown here uses 2 Zener diodes, one to bias the ISL28023 that is ground referenced and a second to bias the ISL28023 with an elevated ground potential. All analog blocks are operational and referenced to the ground pin of the device, however, the communication lines of the second device require level shifting, which is accomplished with the use of bipolar transistors and resistors. The given circuit is a reference design and provides recommended resistor values.