PCF85263ATLSLASHA datasheet(28/102 Pages) NXP

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NXP Semiconductors

PCF85263A

Tiny RTC/Calendar with Alarm Function, Battery Switch-Over, Time Stamp Input, and I2C-bus

aaa-009585

countdown value, WDR

Watchdog clock

counter

WDF

INTA or INTB

duration of Watchdog period after start

may range from WDR to WDR -1 counts

Figure 16. Watchdog single shot mode

7.5.1.3 Watchdog interrupts

The generation of interrupts from the Watchdog functions is controlled via the Watchdog interrupt enable bits;

WDIEA and WDIEB. These bits are in registers INTA_enable (address 29h) and INTB_enable (address 2Ah).

The assertion of the flag WDF can be used to generate an interrupt at pins INTA and INTB. The interrupt can

be generated as a pulsed signal every time the Watchdog counter reaches the end of the countdown period.

Alternatively, as a permanently active signal that follows the condition of bit WDF, WDF remains set until cleared

by command.

When enabled, interrupts are triggered every time the Watchdog counter reaches the end of the countdown

period and even if the WDF is not cleared, an interrupt pulse can be generated.

See Section 7.9 for interrupt control.

7.6 RAM byte

Bit

Symbol

Value

Description

7 to 0

B[7:0]

0000 0000 [1] to

1111 1111

RAM content

Table 18. RAM_byte - 8-bit RAM register (address 2Ch) bit description

[1]

Default value.

The PCF85263A provides a free RAM byte, which can be used for any purpose, for example, status bits of the

system.

7.7 Timestamps

There are three timestamp registers that can be independently configured to record the time for battery switch-

over events and/or transitions on the TS pin.

Each timestamp register has an associated flag. It is also possible to generate an interrupt signal for every

timestamp register update.

Timestamps work in both RTC and stop-watch mode. During battery operation, the mechanical switch detector

can also be used to trigger the timestamp.

PCF85263A

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

Product data sheet

Rev. 5.4 — 12 December 2025

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