M48T512Y, M48T512V

Clock operations

Doc ID 5747 Rev 6

13/23

One method for ascertaining how much calibration a given M48T512Y/V may require

involves setting the clock, letting it run for a month and comparing it to a known accurate

reference and recording deviation over a fixed period of time.

Calibration values, including the number of seconds lost or gained in a given period, can be

allows the designer to give the end user the ability to calibrate the clock as the environment

requires, even if the final product is packaged in a non-user serviceable enclosure. The

designer could provide a simple utility that accesses the calibration bits. For more

ST website.

Figure 7.

Crystal accuracy across temperature

Figure 8.

Calibration waveform

AI00999

–160

0

10203040506070

Frequency (ppm)

Temperature

°C

80

–10

–20

–30

–40

–100

–120

–140

–40

–60

–80

20

0

–20

ΔF

= -0.038

(T - T

F

ppm

C

2

T

AI00594B

NORMAL

POSITIVE

CALIBRATION

NEGATIVE

CALIBRATION