In some applications, a current measurement is required for each half-bridges. This measurement has done inserting a shunt resistor between the source of the low-side and the common SL pin of the MOSFET driver.
The drain-source overvoltage of the low-side monitors the VSHx - VSL where VSHx is the phase voltage of the considered half-bridge.
In general the MOSFETs used for one half-bridge (high-side and low-side) are symmetrical.
The individual configuration of the drain-source overvoltage (DSOV) threshold of the high-side (HS) and of the low-side (LS) enables the compensation of the shunt resistor inserted at the low-side.
For example:
- the nominal Rdson of the HS and LS is 5 mOhm
- the resistance of the shunt resistor inserted in the LS path is 5 mOhm
Selecting DSOV threshold for LS = 2 x DSOV threshold for HS allows the same trigger current for detection of HS DSOV and LS DSOV.
