L6982 datasheet(17/48 Pages) STMICROELECTRONICS

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This is a second level protection and it should never be triggered in normal operating conditions if the system

is properly dimensioned. In other words, the selection of the external power components and the dynamic

performance determined by the compensation network should guarantee an output voltage regulation within the

overvoltage threshold even during the worst-case scenario in terms of load transitions. The protection is reliable

and able to operate even during normal load transitions for a system whose dynamic performance is not in line

with the load dynamic request. Consequently, the output voltage regulation would be affected.

The L6982 device implements a 1.5 A (IVY_SINK refer to Table 6) negative current limitation to limit the maximum

reversed switch current during the overvoltage operation.

6.5.1

Low consumption mode part number

The overvoltage protection continuously compares the FB pin with 120% nominal output voltage and enables

the low-side MOSFET at the beginning of the switching cycle keeping it active until 1.5 A typ. negative current

limitation is reached, in order to discharge the output capacitor.

The following graph shows the LCM part number behavior during an OVP event.

Figure 18. OVP event low noise mode part number

As soon as the output voltage goes out of the OVP hysteresis (typ. 2%) the L6982 device sets the switching node

on high impedance. It restarts the switching activity accordingly with the main loop regulation of the peak current

mode architecture.

6.5.2

Low consumption mode part number

The following graph shows the LNM part number behavior during an OVP event.

L6982

Overvoltage protection

DS13683 - Rev 1

page 17/48

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