NCL30060

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Table 1. NCL30060 PIN FUNCTION DESCRIPTION

Pin No

Pin Name

Pin Description

1

FB

Feedback Input. The FB pin is the control input to the PWM comparator. A voltage level controlled by the

feedback loop on this pin is compared to the internal ramp establishing power switch on time.

2

CS/ZCD

Current sense and zero current detection. The CS input is used to sense the instantaneous switch cur-

rent in the external power switch during switch on time. A fast−responding high threshold level for short

circuit detection is provided along with a longer blanking time at lower level for overload conditions. Dur-

ing switch off time, this pin monitors the bias winding to detect transformer demagnetization. When

stored energy is depleted the gate drive turns on the power switch initiating the next cycle. This pin also

detects overvoltage conditions through the bias winding. A blanking time prevents false overvoltage trig-

gering due to noise.

3

RT

Maximum on−time adjust. The RT pin establishes the ramp charging current. The PWM comparator es-

tablishes the switch on time from the ramp and FB signal. Pulling the RT pin below the disable threshold

forces the controller in the Armed mode where all switching functions cease.

4

GND

Ground. This is the ground reference for the controller. All bypassing and control components should be

connected to the GND pin with a short trace length to minimize noise.

5

DRV

Drive. The high current capability of the totem pole gate drive makes it suitable to directly control high

gate charge power MOSFETs. The driver stage provides both passive and active pull−down circuits

which force the MOSFET gate off when VCC is below normal operating levels.

6

VCC

IC Supply. This is the positive supply of the controller and source for powering external circuits. Internal

bias will be disabled when external power is sufficient to maintain operation.

7

NC

No−connect. This missing pin provides creepage distance.

8

HV

High−voltage input. Monitors input voltage for brown−out detection and power to operate controller.