R2023K datasheet(36/50 Pages) RICOH

36 / 50 page

R2023K/T

Power-on Reset, Oscillation Halt Sensing, and Supply Voltage

Monitoring

• PON, XST, and VDET

The power-on reset circuit is configured to reset control register1, 2, and clock adjustment register when VDD

power up from 0v.

The oscillation halt sensing circuit is configured to record a halt on oscillation by 32.768-kHz

clock pulses.

The supply voltage monitoring circuit is configured to record a drop in supply voltage below a

threshold voltage of 1.6 or 1.3V.

Each function has a monitor bit.

I.e. the PON bit is for the power-on reset circuit, and XST bit is for the

oscillation halt sensing circuit, and VDET is for the supply voltage monitoring circuit. PON and VDET bits are

activated to “H”. However, XST bit is activated to “L”.

The PON and VDET accept only the writing of 0, but

XST accepts the writing of 0 and 1.

The PON bit is set to 1, when VDD power-up from 0V, but VDET is set to 0,

and XST is indefinite.

The functions of these three monitor bits are shown in the table below.

PON

XST

VDET

Function

Monitoring for the

power-on reset function

Monitoring for the

oscillation halt sensing

function

a drop in supply voltage

below a threshold

voltage of 1.6 or 1.3V

Address

D4 in Address Fh

D5 in Address Fh

D6 in Address Fh

Activated

High

Low

High

When VDD

power up from 0v

Indefinite

accept the writing

0 only

Both 0 and 1

0 only

The relationship between the PON, XST , and VDET is shown in the table below.

PON

XST

VDET

Conditions of supply voltage and

oscillation

Condition of oscillator, and

back-up status

Halt on oscillation, but no drop in

VDD supply voltage below threshold

voltage

Halt on oscillation cause of

condensation etc.

Halt on oscillation and drop in VDD

supply voltage below threshold

voltage, but no drop to 0V

Halt on oscillation cause of drop in

back-up battery voltage

No drop in VDD supply voltage

below threshold voltage and no halt

in oscillation

Normal condition

Drop in

VDD supply voltage below

threshold voltage and no halt on

oscillation

No halt on oscillation, but drop in

back-up battery voltage

Drop in supply voltage to 0v

Power-up from 0v,

R2023K Datasheet(PDF) 36 Page - RICOH electronics devices division

R2023K Datasheet(HTML) 36 Page - RICOH electronics devices division

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

Datasheet Download

Link URL