Pin settings

HVLED001A

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DocID029000 Rev 2

3

Pin settings

Figure 3. Pin connection

Table 2. Pin description

Symbol Pin

Description

HVSU

1

High voltage startup and input voltage detection.

The pin, able to withstand 800 V, is intended to be tied to the input voltage using a low value resistor

(1 k

 typ.) . It embeds the internal startup unit that charges the capacitor connected between the

During the operational mode, the voltage at this pin is used to both - measure the input voltage and

detect input overvoltages.

N.C.

2

Not connected pin.

TOFF

3

A blanking time for zero voltage detection can be set applying a voltage to this pin. A minimum

blanking time is obtained leaving the pin unconnected.

FB

4

Input for loop regulation.

The pin is intended to be directly driven by the phototransistor (emitter-grounded) of an optocoupler

and/or to be connected to the compensation network related to the output voltage primary side

regulation loop.

An upper threshold VOFP detects a failure of the optocoupler.

The burst mode is also related to the voltage applied to this pin.

CTRL

5

This pin is used to disable the IC and generate the soft-start ramp.

External active circuitry can be used to turn-off the application.

ZCD

6

Multiple function pin able to detect the zero current instant, to sense the output voltage for the

primary side regulation and the input voltage for brownout detection. A negative-going edge triggers

the MOSFET's turn-on, while an internal starter unit is active to generate the triggering signal when

not externally available (e.g.: startup).

CS

7

Input to the current sense comparator for the power regulation. A second level overcurrent (OCP)

threshold detects abnormal currents (e.g.: due to transformer's saturation) and, on this occurrence,

activates the second level overcurrent protection procedure.

GND

8

Reference pin.