PCF85063ATLSLASH1 datasheet(28/55 Pages) NXP

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NXP Semiconductors

PCF85063A

Tiny Real-Time Clock/calendar with alarm function and I2C-bus

When reading the timer, the current countdown value is returned and

not the initial value T. Since it is not

possible to freeze the countdown timer counter during read back, it is recommended to read the register twice

and check for consistent results.

Timer source clock frequency selection of 1 Hz and 1⁄60 Hz is affected by the Offset register. The duration of a

program period varies according to when the offset is initiated. For example, if a 100 s timer is set using the 1

Hz clock as source, then some 100 s periods will contain correction pulses and therefore be longer or shorter

depending on the setting of the Offset register. See Section 7.2.3 to understand the operation of the Offset

7.6.3.1 Countdown timer interrupts

The pulse generator for the countdown timer interrupt uses an internal clock and is dependent on the selected

source clock for the countdown timer and on the countdown value T. As a consequence, the width of the

interrupt pulse varies (see Table 37).

TF and INT become active simultaneously.

INT period (s)

Source clock (Hz)

T = 1[1]

T > 1[1]

4 096

1⁄8 192

1⁄4 096

1⁄128

1⁄64

1⁄60

1⁄64

Table 37. INT operation

[1]

T = loaded countdown value. Timer stops when T = 0.

8 Characteristics of the I2C-bus interface

The I2C-bus is for bidirectional, two-line communication between different ICs or modules. The two lines are a

Serial DAta line (SDA) and a Serial CLock line (SCL). Both lines must be connected to a positive supply via a

pull-up resistor. Data transfer may be initiated only when the bus is not busy.

8.1 Bit transfer

One data bit is transferred during each clock pulse. The data on the SDA line must remain stable during the

HIGH period of the clock pulse, as changes in the data line at this time are interpreted as a control signal (see

Figure 18).

mbc621

data line

stable;

data valid

change

of data

allowed

SDA

SCL

Figure 18. Bit transfer

PCF85063A

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

Product data sheet

Rev. 7.1 — 8 November 2023

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