DS1646/DS1646P

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CLOCK ACCURACY (DIP MODULE)

The DS1646 is guaranteed to keep time accuracy to within

±1 minute per month at 25°C. The RTC is

calibrated at the factory by Dallas Semiconductor using nonvolatile tuning elements, and does not require

additional calibration. For this reason, methods of field clock calibration are not available and not

necessary. Clock accuracy is also effected by the electrical environment and caution should be taken to

place the RTC in the lowest level EMI section of the PCB layout. For additional information please see

application note 58.

CLOCK ACCURACY (POWERCAP MODULE)

The DS1646 and DS9034PCX are each individually tested for accuracy. Once mounted together, the

module will typically keep time accuracy to within

±1.53 minutes per month (35 ppm) at 25°C. Clock

accuracy is also effected by the electrical environment and caution should be taken to place the RTC in

the lowest level EMI section of the PCB layout. For additional information please see application note

58.

1646 REGISTER MAP - BANK1 Table 2

DATA

ADDRESS

FUNCTION

1FFFF

-

-

-

-

-

-

-

-

YEAR

00-99

1FFFE

X

X

X

-

-

-

-

-

MONTH

01-12

1FFFD

X

X

-

-

-

-

-

-

DATE

01-31

1FFFC

X

FT

X

X

X

-

-

-

DAY

01-07

1FFFB

X

X

-

-

-

-

-

-

HOUR

00-23

1FFFA

X

-

-

-

-

-

-

-

MINUTES

00-59

1FFF9

OSC

-

-

--

--

-

SECONDS

00-59

1FFF8

W

R

X

XX

XX

X

CONTROL

A

OSC

= STOP BIT

R = READ BIT

FT = FREQUENCY TEST

W

= WRITE BIT

X = UNUSED

NOTE:

All indicated “X” bits are not dedicated to any particular function and can be used as normal RAM bits.

RETRIEVING DATA FROM RAM OR CLOCK

device architecture allows ripple-through access to any of the address locations in the NVSRAM. Valid

until the next address access.