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After IC1150 has started, the startup current is cut off.
The current of Startup Circuit is supplied as constant current source in IC1150 and as charge
current for the capacitor connected between Vcc terminal and GND out side of IC1150 until Vcc
reaches 14.4V.
When Vcc reaches 14.4V, the Startup Circuit is cut off, then oscillation starts.
After then, power of IC1150 is supplied from control coil.
In case, the power failure or short out of the load, when Vcc becomes 9.0V; the oscillation stops,
furthermore Vcc becomes 7.1V the Startup Circuit starts up and Vcc starts to rise.
Startup Circuit Timing Chart
Function of Z/C Terminal
When voltage of Z/C reaches 0.25V, Gate signal is output and Drain current starts to flow.
Function of F/B terminal
F/B signal decides Switching ON width in low voltage controlling.
8
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