Datasheet NCL30000 (ON Semiconductor) - 4

NCL30000 Table 1. PIN FUNCTION DESCRIPTION Pin Name Function
1 MFP The multi-function pin is connected to the internal error amplifier. By pulling this pin below the Vuvp threshold, the controller is disabled. In addition, this pin also has an over voltage comparator which will disable the controller in the event of a fault. 2 COMP The COMP pin is the output of the internal error amplifier. A compensation network is connected between this pin and ground to set the loop bandwidth. Normally this bandwidth is set at a low frequency (typically 10 Hz − 20 Hz) to achieve high power factor and low total harmonic distortion (THD). 3 Ct The Ct pin sources a regulated current to charge an external timing capacitor. The PWM circuit controls the power switch on time by comparing the Ct voltage to an internal voltage derived from VControl. The CT pin discharges the external timing capacitor at the end of the on time cycle. 4 CS The CS input is used to sense the instantaneous switch current in the external MOSFET. This signal is filtered by an internal leading edge blanking circuit. 5 ZCD The voltage of an auxiliary zero current detection winding is sensed at this pin. When the ZCD control block circuit detects that the winding has been demagnetized, a control signal is sent to the gate drive block to turn on the external MOSFET. 6 GND This is the analog ground for the device. All bypassing components should be connected to the GND pin with a short trace length. 7 DRV The high current capability of the totem pole gate drive (+0.5/−0.8 A) makes it suitable to effectively drive high gate charge power MOSFETs. The driver stage provides both passive and active pull down circuits that force the output to a voltage less than the turn-on threshold voltage of the power MOSFET when VCC(on) is not reached. 8 VCC This pin is the positive supply of the controller. The circuit starts to operate when VCC exceeds VCC(on), nominally 12 V and turns off when VCC goes below VCC(off), typically 9.5 V. After startup, the operating range is 10.2 V up to 20 V. AC EMI Dout Line FILTER Input Ï RSU Cin Ra D1 Ï R Cv R x b Ï 8 VCC RL 5 IN2+ OUT2 + R1 RZCD 7 IN2− 6 Ï − Rt ÏÏ
NCL30000 NCS1002
1 VCC 8 2 MFP Q1 IN1− ÏÏ OUT1 − C1 2 1 IN1+ 3 DRV 7 COMP + R2 Ccomp 3 GND C GND 6 T R 4 y Cc 4 CS ZCD 5 Ctim COUT Rc RLED RCS
Figure 2. Simplified Flyback Application with Secondary side Constant Current Control http://onsemi.com 3