L99VR02XP datasheet(37/50 Pages) STMICROELECTRONICS

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4.12

Undervoltage lockout (UVLO)

The undervoltage lockout (UVLO) circuit allows a fast regulating element to turn-off (activating the internal fast

output discharge circuit) if the input voltage drops below the threshold, VUVLO_fall, avoiding so undesired

unknown output state during low input voltage. When the input voltage is above the VUVLO_rise threshold, the

regulating element is again turned on.

Figure 56. Undervoltage lock out on output voltage

4.13

Support to ISO26262

Even if not designed as a safety hardware element, the device contains some features that can be used to

support applications that need to fulfill functional safety requirements. Analysis of the IC’s capability to reach the

required safety level, should be made at system level under user responsibility.

The following safety mechanisms have been implemented:

Table 20. Implemented safety mechanism

Description

SM1

Thermal sensor acting by TW pin

SM2

Overtemperature protection

SM3

Limitation on maximum output current

SM4

Output voltage VO monitoring for undervoltage detection

SM5

Output voltage VO monitoring for overvoltage detection

SM6

RST reset assertion in case of VO undervoltage detection

Besides the internal watchdog to check microcontroller correct functionality can be considered as a safety

mechanism at system level.

More details about functional safety can be found in the device safety manual, provided on customer request.

L99VR02XP

Application information

DS14686 - Rev 1

page 37/50

L99VR02XP Folha de dados(PDF) 37 Page - STMicroelectronics