Equation 10

(10)

ROVP=RHV∙ ViOVP_tℎ

VIN−OVP−VBR−IN

VIN−ON

Equation 11

(11)

RBR=RHV∙ VBR−IN

VIN−ON−VBR−IN

In the above formulas,

VIN_ONandVIN_OVParetheDCinputvoltageswhichtriggerbrown-inandinput

overvoltage protection respectively.

The resistor RHV is used to start up the converter and also as part of the voltage divider, once HV and iOVP

are connecter together. Its value is arbitrarily selected, with the recommendation to be few tens MΩ at least to

minimize the residual consumptions from the input mains.

It is worth noting that the thresholds VIN-ON and VIN-OFF (the input voltage values triggering brown-in and

brown-out respectively) cannot be set independently but are linked to each other. The DC bus voltage value that

turns off the device is thus calculated with the following equation.

Equation 12

(12)

VIN−OFF=VIN−ON∙VBR−OUT

VBR−IN

A 10 nF filter capacitor placed between BR pin and GND is necessary to avoid misbehavior of the brown-out logic

when a high voltage start-up unit is activated.

The brown-in/out function can be disabled connecting the BR to GND.

Figure 27. Brown-in/out and input OVP: internal schematic

5.14

Configure Brown-In/Out and OVP protection

The pins iOVP and BR can be easily configured in different combinations, as reported in Table 7.

VIPERGAN65

Configure Brown-In/Out and OVP protection

DS14005 - Rev 2

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