ing edge causes an interrupt request on the interrupt line #0. If the overvoltage situation is still present,
OV is SET again. The bridge is switched off automatically at overvoltage.
UNV: This bit is SET as soon as the voltage on VS pin falls below the undervoltage threshold Vsmin.
This rising edge causes a interrupt request on the interrupt line #0. This bit is RESET by software only. If
the undervoltage situation is still present, UNV remains SET. The bridge is not switched off automatically
at undervoltage.
OVT1: This bit is SET as soon as the temperature of the chip exceeds 130
°C. This rising edge causes
an interrupt request on the interrupt line #0. This bit is RESET by software only. If the overtemperature
situation is still present, OVT1 remains SET. The bridge is not switched off automatically at overtem-
perature.
OVT2: This bit is SET as soon as the temperature of the chip exceeds 150
°C. This rising edge causes
an interrupt request on the interrupt line #0. This bit is RESET by software only. If the overtemperature
situation is still present, OVT2 remains SET. The bridge is not switched off automatically at overtem-
perature.
Warning: All power bridge flags are ored to form one interrupt request which is connected to edge sen-
sitive interrupt input #0 (see Fig. 11). The interrupt request is stored in a flipflop which is automatically
cleared when the interrupt service routine is entered. If other interrupt flags of the power bridge become
active before the flag which caused the interrupt is cleared by software, the new request is not stored in
the flipflop. In order not to miss any interrupt request it is recommended to check all interrupt flags of the
power bridge after clearing the first flag. Then the interrupt service routine may be left.
Voltage regulator
The on chip voltage regulator provides regulated 5V to supply the microcontroller and it’s periphery. This
voltage is available at pin VCC to supply external components and connect a capacitor to optimize EMI
performance. The regulator has a normal and a standby operating mode. When the controller enters
STOP mode, the regulator is switched to stand by operation. In this mode the power consumption as
well as the ability to supply current (also to external devices) is drastically reduced. A return to RUN
mode or a reset switches the regulator back to normal mode.
The voltage regulator also provides a reset signal POR at power up and power down to guarantee a well
defined state of the device at undervoltage conditions (see Fig. 1).
POR activates the reset pull down transistor performing a complete chip reset. In the same way a reset
POWER SUPPLY (continued)
undefined
VCC
POR
5V
V Reset OFF
Reset ON
V
t
Reset UD
V
Figure 1. Power up/down characteristics
L9942
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