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SQJQ144AE
TrenchFET
®
Gen IV
Power MOSFETs
VOMA617A
Phototransistor
Output Optocoupler
(TR5/TR6 in Figure 2) and then filtered with a Vishay IHDM 2.5µH
inductor (L2 in Figure 2) and C2 (in Figure 2) to provide 12V
DC
.
The Vishay IHDM series is a customizable design in terms of
inductance value, voltage rating, terminations, and mounting
orientation. In order to minimize the MOSFET losses and keep
the converter efficiency as high as possible, three SQJQ144AE
devices were connected in parallel for each switch.
The control signals for the low-voltage rectification MOSFETs are
generated by the same control IC on the high-voltage side and
transmitted to the low-voltage side using a pulse transformer to
ensure that galvanic isolation is maintained.
The voltage is measured on the output side and transmitted
to the control IC on the high-voltage side using the Vishay
VOMA617A optocoupler (Figure 3). An important parameter of
this component is a high CTR (Current Transfer Ratio) with a
low input current, and a high isolation test voltage (3750V
RMS
) to
maintain the galvanic isolation safely.
A cost effective control method has been presented that
provides the necessary galvanic isolation barrier between
the high-voltage and low-voltage buses to meet the safety
requirements of today's electric/hybrid vehicles. ▼
Figure 3: VOMA617A control cir-
cuit schematic (Source: Vishay)
Figure 2: Simplified schematic of the power stage (Source: Vishay)
