4.7

Overvoltage detection by advanced thermal warning read-out

The TW pin also provides diagnostics about output overvoltage (OV); to distinguish between a thermal warning

event and an output overvoltage event, two different signals are generated at the same TW output pin. How

reported in the previous paragraph a thermal warning event detection sets the TW pin LOW, instead an output

overvoltage event generates a square wave at the TW pin (Figure 35. Square wave on TW pin generated during

an overvoltage). Overvoltage detection has higher priority than thermal warning detection so that concurrence of

thermal warning and over voltage events leads to a square wave like in the case of overvoltage detection (as

shown in Figure 36. Warning signal caused by overvoltage and thermal warning on TW pin).

Figure 35. Square wave on TW pin generated during an overvoltage

TW

t

Tw_per

A typical example of thermal warning and overvoltage failures management is depicted in Figure 36. Warning

signal caused by overvoltage and thermal warning on TW pin.

Figure 36. Warning signal caused by overvoltage and thermal warning on TW pin

Vo

T

Vo_hth

TW

150ºC

t

t

t

L99VR01

Application information

DS13649 - Rev 4

page 20/40