LP3871, LP3874

SNVS225H – FEBRUARY 2003 – REVISED JUNE 2015

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Device Functional Modes (continued)

7.4.3 ERROR Flag Operation

The LP3871 produces logic low signals at the ERROR Flag pin when the output drops out of regulation due to

low input voltage, current limiting, or thermal limiting. This flag has a built-in hysteresis. The timing diagram in

Figure 10 shows the relationship between the ERROR flag and the output voltage. In this example, the input

voltage is changed to demonstrate the functionality of the ERROR Flag.

The internal ERROR flag comparator has an open drain output stage. Hence, the ERROR pin must be pulled

high through a pullup resistor. Although the ERROR flag pin can sink current of 1mA, this current is energy drain

from the input supply. Hence, the value of the pullup resistor must be in the range of 10 k

Ω to 1 MΩ. The

ERROR pin must be connected to ground if this function is not used. It must also be noted that when the

shutdown pin is pulled low, the ERROR pin is forced to be invalid for reasons of saving power in shutdown

mode.

Figure 10. ERROR Flag Operation

10

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