NXP Semiconductors

PCF85063A

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

Input or input/output pins must always be at a defined level (VSS or VDD) unless otherwise specified.

Pin

Symbol

PCF85063AT

PCF85063ATL PCF85063ATT

Type

Description

INT[1]

3

4

3

output

interrupt output (open-drain)

VSS

4

5[2]

4

supply

ground supply voltage

SDA[1]

5

6

5

input/output serial data line

SCL[1]

6

7

6

input

serial clock input

n.c.

-

8

-

-

not connected

CLKOUT

7

9

7

output

clock output (push-pull)

VDD

8

10

8

supply

supply voltage

Table 3. Pin description...continued

[1]

NXP recommends tying VDD of the device and VDD of all the external pull-up resistors to the same Power Supply.

[2]

The die paddle (exposed pad) is connected to VSS through high ohmic (non-conductive) silicon attach and should be electrically isolated. It is good

engineering practice to solder the exposed pad to an electrically isolated PCB copper pad as shown in Figure 37"Footprint information for reflow soldering

of SOT1197-1 (DFN2626-10) of PCF85063ATL" for better heat transfer but it is not required as the RTC doesn’t consume much power. In no case should

traces be run under the package exposed pad.

7 Functional description

The PCF85063A contains 18 8-bit registers with an auto-incrementing register address, an on-chip 32.768 kHz

oscillator with integrated capacitors, a frequency divider which provides the source clock for the Real-Time

Clock (RTC) and calender, and an I2C-bus interface with a maximum data rate of 400 kbit/s.

The built-in address register will increment automatically after each read or write of a data byte up to the register

11h. After register 11h, the auto-incrementing will wrap around to address 00h (see Figure 5).

aaa-004431

address register

00h

auto-increment

wrap around

01h

02h

03h

...

0Fh

10h

11h

Figure 5. Handling address registers

All registers (see Table 4) are designed as addressable 8-bit parallel registers although not all bits are

implemented. The first two registers (memory address 00h and 01h) are used as control and status register.

The register at address 02h is an offset register allowing the fine-tuning of the clock; and at 03h is a free

RAM byte. The addresses 04h through 0Ah are used as counters for the clock function (seconds up to years

counters). Address locations 0Bh through 0Fh contain alarm registers which define the conditions for an alarm.

The registers at 10h and 11h are for the timer function.

The Seconds, Minutes, Hours, Days, Months, and Years as well as the corresponding alarm registers are all

coded in Binary Coded Decimal (BCD) format. When one of the RTC registers is written or read, the contents

of all time counters are frozen. Therefore, faulty writing or reading of the clock and calendar during a carry

condition is prevented. For details on maximum access time, see Section 7.4.

PCF85063A

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© 2023 NXP B.V. All rights reserved.

Product data sheet

Rev. 7.1 — 8 November 2023

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