EM6620WS11 datasheet(7/56 Pages) EMMICRO

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EM6620

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3. Power Supply

The EM6620 is supplied by a single external power supply between VDD (Vbat) and VSS (ground). A built-in

voltage regulator generates Vreg providing regulated voltage for the oscillator and the internal logic. The

output drivers are supplied directly from the external supply VDD. A internal power configuration is shown in

Figure 5.

To supply the internal core logic it is possible to use either the internal voltage regulator (Vreg < VDD) or Vbat

directly ( Vreg = VDD). The selection is done by metal 1 mask option. By default the voltage regulator is used.

Refer to chapter 16.1.3 for the metal mask selection.

The internal voltage regulator is chosen for high voltage systems. It saves power by reducing the internal core

logic’s power supply to an optimum value. However, due to the inherent voltage drop over the regulator the

minimal VDD value is restricted to 1.4V .

A direct Vbat connection can be selected for systems running on a 1.5V battery. The 1kOhm resistor together

with the external capacitor on Vreg is filtering the VDD supply to the internal core. In this case the minimum

VDD value can be as low as 1.2 V.

Figure 5. Internal power supply

R e f. Lo gic

Te rm in al

Vreg

T e rm inal

Vba t

R e f. LC D

All Pad

in put &

outpu t

buffers,

SV LD

C ore Log ic ,

LC D Logic,

Osc illa tor

V oltage m ultiplie r,

LC D outputs

M1 B

M1 A

1kO h m

MV reg

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