User Guide
10 of 46
Rev. 1.0
2022-03-09
48V Battery Switch Reference Design
R 48V BATT Switch10
System and functional description
control of the five MOSFET pairs by a single gate driver channel and leaves the second gate driver channel of
the
2ED4820-EM
available for the control of the precharge circuit.
The power stage is controlled by channel A of the gate driver. Special care has been taken to ensure an even
current distribution between the MOSFETs. This includes decoupling of the sources of the different MOSFET
pairs by source resistors (R9 … R13) as well as equal trace length for each current branch in the layout.
Figure 7
Even current distribution by equal trace length for each current branch
2.2.3
Precharge circuit
Figure 8
Precharge circuit
Many loads on the 48V power domain have a big capacitance like a DC-link capacitor or EMC filter at their input.
Switching onto an uncharged capacitor will cause a high inrush current, limited only by the ESR of the capacitor
as well as other resistances (cables, connectors, battery) in the system.
The high inrush current may inadvertently trip the overcurrent protection. To avoid this, the capacitor needs to
be precharged before activating the main switch. Therefore, a seperate precharge path is implemented in
