Datasheet L99VR01 (STMicroelectronics) - 21

L99VR01 Enable Figure 35. Example of output voltage selection
SELx pins are internally connected to GND via pull down current source.
4.4 Enable
The L99VR01 is enabled/disabled by the enable input; a high voltage signal switches the regulator ON. When the enable pin is set low, the output is switched-off, the current consumption of the device becomes as low as 1 μA and the Fast Output Discharge circuit is activated. It may happen that the enable pin must be driven by components supplied at a voltage different from the regulator supply voltage. In this case the EN input pin must be set high only once Vs > 1.5 V. A solution to drive the enable pin is depicted in the following figure.
Figure 36. Typical example of enable control
In any case, since the enable input voltage is linked to the maximum DC supply voltage (VS) applied to the L99VR01 (-0.3 V to Vs + 0.3 V), special care must be adopted in driving EN pin to avoid exceeding absolute maximum rating.
DS13649
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Rev 2 page 21/47
Document Outline Cover image Product status link / summary Features Description 1 Block diagram and pins description 2 Electrical specifications 2.1 Absolute maximum ratings 2.2 Thermal data 2.2.1 Thermal resistance 2.2.2 Thermal protection 2.3 Electrical characteristics 2.4 Electrical characteristics curves 3 Test circuit and waveforms plot 3.1 Load regulation 4 Application information 4.1 Voltage regulator 4.2 Output current limitation 4.3 Output voltage selection 4.4 Enable 4.5 Reset 4.6 Autonomous watchdog 4.7 Thermal warning and thermal shutdown 4.8 Overvoltage detection by advanced thermal warning read-out 4.9 Fast output discharge 4.10 Undervoltage lockout UVLO 4.11 Functional safety management 5 Application 6 Package and PCB thermal data 6.1 PowerSSO-12 Thermal data 6.2 SO-8 thermal data 7 Package information 7.1 PowerSSO-12 package information 7.2 SO-8 package information 7.3 PowerSSO-12 packaging information 7.4 SO-8 packaging information 8 Order codes Revision history Contents List of tables List of figures