ADBMS2950BCCSZ datasheet(72/97 Pages) AD

72 / 97 page

ADBMS2950B

Data Sheet

Rev. 0 | Page 72 of 97

the horizontal axis (direction of the current flow according to

the figures in this chapter) helps to achieve this goal.

The differential sense lines must be connected as short as

possible to the sense resistor, in the example soldered to the

bottom side of the PCB. The GND connection of the shunt

must be done directly at the shunt’s GND pad to the PCB GND

plane. This ensures separation of the GND currents from the

sense lines and avoids false differential signals. The low

impedance of the GND connection ensures minimum GND

shift in the presence of AC GND currents that appear as a

common mode signal on the input, which could translate to a

differential signal. In typical applications, the high voltage

resistive dividers cause DC GND currents. Whereas any voltage

transients between the high voltage and the chassis-GND

network causes AC currents across the shunt resistor's ground

connection to charge the (parasitic) capacitance of all isolation

components. A typical event causing such voltage transients is

the closing of the first high voltage link contactor before the

precharging starts. This event suddenly connects Y-capacitors

and parasitic capacitors to the HV battery leading to recharging

of all capacitors between chassis-GND and the HV network.

Besides that, the power electronics of the inverter and other

components cause chassis ground to HV network noise.

Figure 51. Current Sense Input Filtering Schematic

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