Vdd

The Feedback Voltage, VFB, is directly proportional to the output power of the converter. An internal 6.7 kQ resistor pulls-up the FB voltage to the internal 6.5 V reference. An external optocoupler pulls down the FB voltage to regulate the output voltage of the system. The optocoupler is off during power up and output overload conditions allowing the FB voltage to reach its maximum level of TBD. The NCP1652 monitors the FB voltage to detect an overload condition. A typical startup time of a...

Typical Power Supply with PFC

A typical power supply consists of a boost PFC preregulator creating an intermediate 400 V bus and an isolated dc-dc converter producing the desired output voltage as shown in Figure 51. This architecture has two power stages. designer familiarity and a vast range of available components. But, because it processes the power twice, the search is always on for a more compact and power efficient solution. The NCP1652 controller offers the convenience of shrinking the front-end converter PFC...

High Voltage Startup Circuit

The NCP1652 internal high voltage startup circuit eliminates the need for external startup components and provides a faster startup time compared to an external startup resistor. The startup circuit consists of a constant current source that supplies current from the HV pin to the supply capacitor on the VCC pin CCC . The startup current Istart is typically 5.5 mA. The OUTA and OUTB drivers are enabled and the startup current source is disabled once the VCC voltage reaches VoC on , typically...