PCF8523TS(2012) 查看數據表（PDF） - NXP Semiconductors.

零件编号

产品描述 (功能)

生产厂家

PCF8523TS
(Rev.:2012)

Real-Time Clock (RTC) and calendar

NXP Semiconductors. 

NXP Semiconductors

PCF8523

Real-Time Clock (RTC) and calendar

8.8.3 Offset calibration workflow

The calibration offset has to be calculated based on the time. Figure 18 shows the

workflow how the offset register values can be calculated:

Measure the frequency on pin CLKOUT:

fmeas

Example

32768.48 Hz

Convert to time:

tmeas = 1 / fmeas

30.5171 µs

Calculate the difference to the ideal

period of 1 / 32768.00:

Dmeas = 1 / 32768 - tmeas

Calculate the ppm deviation compared

to the measured value:

Eppm = 1000000 × Dmeas / tmeas

0.000447 µs

14.6484 ppm

Calculate the offset register value:

Mode = 0 (low power):

Offset value = Eppm / 4.34

Mode = 1 (fast correction)

Offset value = Eppm / 4.069

Fig 18. Offset calibration calculation workflow

3.375

3.600

3 correction pulses

are needed

4 correction pulses

are needed

013aaa683

PCF8523

Product data sheet

All information provided in this document is subject to legal disclaimers.

Rev. 4 — 5 July 2012

© NXP B.V. 2012. All rights reserved.

31 of 74

Share Link: