PCF85263ATT/AJ View Datasheet(PDF) - NXP Semiconductors.

Part Name

Description

MFG CO.

PCF85263ATT/AJ

Tiny Real-Time Clock/calendar with alarm function, battery switch-over, time stamp input, and I2C-bus

NXP Semiconductors. 

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NXP Semiconductors

PCF85263A

Tiny RTC with alarm, battery switch-over, and I2C-bus

8.8 Offset register

The PCF85263A incorporates an offset register (address 24h) which can be used to

implement several functions, such as:

• Accuracy tuning

• Aging adjustment

• Temperature compensation

Table 23. Offset - offset register (address 24h) bit description

Bit

Symbol

Value

Description

7 to 0 OFFSET[7:0]

see Table 25 offset value

There are two modes which define the correction period, normal mode and fast mode.

The normal mode is suitable for offset trimming. The fast mode is suitable for dynamic

offset correction e.g. implementing a temperature correction. The fast mode consumes

more current. Offset mode is defined by bit OFFM in the Oscillator register (Section 8.10).

Table 24. OFFM bit - oscillator control register (address 25h)

See Section 8.10 on page 42.

Bit

Symbol

Value

Description

6

OFFM

offset mode bit

0[1]

normal mode: correction is made every 4

hours; 2.170 ppm/step

1

fast mode: correction is made once every 8

minutes;2.0345 ppm/step

[1] Default value.

For OFFM = 0, each LSB introduces an offset of 2.170 ppm. For OFFM = 1, each LSB

introduces an offset of 2.0345 ppm. The offset value is coded in two’s complement giving

a range of +127 LSB to 128 LSB, see Table 25.

Table 25. Offset values

OFFSET[7:0]

Offset value in

decimal

01111111

01111110

:

0000 0010

0000 0001

0000 0000[1]

11111111

11111110

:

1000 0001

1000 0000

[1] Default value.

+127

+126

:

+2

+1

0

1

2

:

127

128

Offset value in ppm

Normal mode

OFFM = 0

+275.590

+273.420

:

+4.340

+2.170

0[1]

2.170

4.340

:

275.590

277.760

Fast mode

OFFM = 1

+258.3815

+256.3470

:

+4.0690

+2.0345

0[1]

2.0345

4.0690

:

258.3815

260.416

PCF85263A

Product data sheet

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

Rev. 4.1 — 27 November 2015

© NXP Semiconductors N.V. 2015. All rights reserved.

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