CoolSET

™Q1

ICE2QR0665G

Functional Description

Data Sheet

9

V2.1, 2014-04-01

3

Functional Description

3.1

VCC Pre-Charging and Typical VCC Voltage During Start-up

In ICE2QR0665G, a startup cell is integrated into the CoolMOS

of a high voltage device and a controller, whereby the high voltage device is controlled by the controller. The

startup cell provides a pre-charging of the VCC capacitor till VCC voltage reaches the VCC turned-on threshold

the amplitude of the current through the high voltage device is only determined by its channel resistance and

can be as high as several mA. After the VCC voltage is high enough, the controller controls the high voltage

device so that a constant current around 1mA is provided to charge the VCC capacitor further, until the VCC

increase near linearly and the charging speed is independent of the mains voltage level.

Figure 4

VCC voltage at start up



The time taking for the VCC pre-charging can then be approximately calculated as:

and the IC begins to operate with soft-start. Due to power consumption of the IC and the fact that there is still no

energy from the auxiliary winding to charge the VCC capacitor before the output voltage is built up, the VCC

voltage drops (Phase II). Once the output voltage is high enough, the VCC capacitor receives the energy from

output load.

3.2

Soft-start

stresses for the switch, diode and transformer are minimized. The soft-start implemented in CoolSET

the peak voltage on CS pin will increase step by step from 0.32V to 1V finally.