AN4467 datasheet(12/33 Pages) STMICROELECTRONICS

12 / 33 page

Power supplies

AN4467

12/33

DocID026156 Rev 2

Figure 3. Optional LCD power supply scheme

•

Option 1: LCD power supply is provided by a dedicated VLCD supply source, VSEL

switch is open.

•

Option 2: LCD power supply is provided by the internal step-up converter, VSEL switch

is closed, an external capacitance is needed for correct behavior of this converter.

Note:

The availability of the VLCD rails depend on device package.

1.3

Reset and power supply supervisor

The input supply to the main and low-power regulators is monitored by a power-on/power-

down/brownout reset circuit. Power-on/power-down reset are a null power monitoring with

fixed threshold voltages, whereas brownout reset gives the choice between several

thresholds with a very low, but not null, power consumption.

In addition, the STM32L0xx embeds a programmable voltage detector that compares the

power supply with the programmable threshold. An interrupt can be generated when the

power supply drops below the VPVD threshold and/or when the power supply is higher than

the VPVD threshold. The interrupt service routine then generates a warning message and/or

puts the MCU into a safe state.

AN4467 Datasheet(PDF) 12 Page - STMicroelectronics