SR036/SR037
Applications Information
Functional Block Diagram
HVIN
Operating Principle
Gate Source
The SR03x operates by controlling the conduction angle of the
external MOSFET as shown in Figure 1. When the rectified AC
voltage is below the VTH threshold, the pass transistor is turned
on. The pass transistor is turned off when the rectified AC is
aboveHVIN(off).Outputvoltage(Vunreg)decaysduringtheperiods
when the switch is off and when the rectified AC is below the
output voltage. The amount of decay is determined by the load
and the value of C1. Since the switch only conducts with low
voltages across it, power dissipation is minimized.
CM
VREF
Reg
VOUT
GND
Switch ON
HVIN
VTH
VUNREG
VREG
not to scale
Figure 1: Typical Waveforms
4
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