DocID17496 Rev 7

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AN3216

Power supplies

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2.1.2

Independent LCD supply

two ways:

•

It can receive, from an external circuitry, the desired maximum voltage that is provided

on the segment and common lines to the glass LCD by the microcontroller.

•

It can also be used to connect an external capacitor that is used by the microcontroller

for its voltage step-up converter. This step-up converter is controlled by software to

provide the desired voltage to the segment and common lines of the glass LCD. Refer

to the specific product datasheet for the capacitor value.

The voltage provided to the segment and common lines defines the contrast of the glass

LCD pixels. This contrast can be reduced when the dead time between frames is

configured.

2.1.3

Voltage regulator

The internal voltage regulator is always enabled after reset. It can be configured to provide

consumption but lowers the maximum acceptable core speed. Consumption ranges in

decreasing consumption order are as follows:

•

•

Range 2 allows CPU frequency up to 16 MHz

•

Range 3 allows CPU frequency up to 4 MHz

Voltage regulator works in three different modes depending on the application modes.

•

and digital peripherals).

•

In Stop mode, Low power run and Low power wait modes, the regulator supplies low

•

In Standby mode, the regulator is powered off. The contents of the registers and SRAM

are lost except for those concerned with the Standby circuitry.