Figure 41. Warning signal caused by overvoltage and thermal warning on TW pin

Vo

T

Vo_hth

TW

150ºC

t

t

t

4.9

Fast output discharge

To assure a quick discharge of the external capacitor tied to the output pin down to around 1.3 V the L99VR01

uses an internal pulldown circuit. Activated each time the EN pin goes low, during thermal shut down and during

undervoltage lockout, the output current will flow through the pulldown resistor of the fast output discharge circuit

to ground. The fast output discharge feature is available for the output voltages Vo= 2.5 V (SELx = [1;0;0]) Vo=

2.8 V (SELx = [1;0;1]) Vo= 3.3 V (SELx = [1;1;0]) and Vo= 5 V (SELx = [1;1;1]).

4.10

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 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.

L99VR01

Fast output discharge

DS13649 - Rev 3

page 25/47