7
Topology sum-up
The low side topology and its dedicated non-insulated driver allow to easily replace electromechanics and/or
passive elements while dealing with the inrush current into a complete solid state solution. This results in the
following advantages for the designers:
•
Relay replacement with SCRs
–
Full solid-state solution
–
No moving parts resulting in high reliability and lifetime operation
–
EMI noise reduction (no bounce)
–
Fastest response against line dips (IEC61000-4-11)
•
AC polarity sense not required
–
No added reverse power losses
–
SCR gate naturally switched gate current to positively biased SCR
•
Easy to drive
–
Single ENABLE pin
–
Can be driven from MCU
–
SCR gates self-powered by AC line
–
Relay existing control can be used to drive the SCR bypass
–
PWM gate signal allows reducing driver power consumption
•
Easy to implement
–
TO220AB SCR tab can be put on the same heatsink without insulated transfer interface material
–
SMD packages available for SCRs
–
Only few SMD components used to drive the circuit (SOT223 and SMA flat)
•
Insulated power supply not required
–
Driver reference is common with GND DC bus
•
Mixed bridge function available
–
A single µc pin required to ensure soft start operation
–
Compatible with digital soft start (mixed bridge topology) for higher power AC-DC
–
No more passive components for inrush (NTC / PTC)
UM2948
Topology sum-up
UM2948
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Rev 1
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