M41T60 datasheet(11/23 Pages) STMICROELECTRONICS

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M41T60

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The second approach is better suited to a

manufacturing environment, and involves the

use of the Frequency Test (FT) pin. The FT pin

will toggle at 512Hz when the ST Bit is set to

'0,' and the OUT Bit and FT Bit are set to '1.'

Any measured deviation from the 512Hz

frequency indicates the degree and direction

of oscillator frequency shift at the test

temperature. For example, a reading of

512.010124Hz would indicate a +20 ppm

oscillator frequency error, requiring a –10

(XX001010) to be loaded into the Calibration

Byte for correction.

Note: Setting or changing the Calibration Byte

does not affect the Frequency Test output

frequency. the FT pin is an open drain pin

which requires a pull-up resistor to VCC for

proper operation. A 500-10k resistor is

recommended in order to control the rise time.

Table 2. Register Map

Keys: 0 = Must be set to '0.'

CB0, CB1 = Century Bits

FT = Frequency Test Bits

OFIE = Oscillator Fail Interrupt Enable Bit

OUT = Output level

S = Sign Bit

ST = STOP Bit

Address

Data

Function/Range

BCD Format

10 Seconds

Seconds

00-59

OFIE

10 Minutes

Minutes

00-59

10 Hours

Hours

00-23

00000

Day

01-07

10 Date

Date

01-31

CB1

CB0

10 M.

Month

Century/Month

0-3/01-12

10 Years

Years

Year

00-99

OUT

Calibration

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