Low Voltage Start-up Controller for 4-85V Input Voltage DC/DC Power Supply
The SCM9603B which has a built-in 85V high voltage transistor works over a wide input voltage range from 4VDC to 85VDC is suitable for wide input voltage DC/DC power supply. When the VDD voltage is less than 8V, the chip begins to charge the VDD pin bypass capacitance. And Large bypass capacitor charge current is up to 20mA when input/output voltage delta is 1V.When the VDD voltage exceeds 10V, the chip stops charging the VDD pin bypass capacitor. At this time, power is supplied by the auxiliary winding and the chip's working current is reduced to 150uA.
Moreover, the SCM9603B has built-in over-temperature protection which improves its reliability.
▶ Wide input voltage range, 4VDC to 85VDC
▶ Small SOT-23 package, benefits a low-cost design
▶ Large bypass capacitor charge current, up to 20mA (input/output voltage delta 1V)
▶ Output charge current >2mA at low input voltage (4V)
▶ Adjustable start-up time set by VDD bypass capacitor
▶ Built-in Over-temperature protection
Typical Application Circuit: