PCF85263ATLSLASHA datasheet(62/92 Pages) NXP

62 / 92 page

NXP Semiconductors

PCF85263A

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

Figure 37 shows the waveforms that can be expected. sample clock, vdd_int and stop

are internal nodes. vdd_int is the supply which operates the IC and will be either VDD or

VBAT, depending on the state of the battery switch-over.

sample clock, 16 Hz

TS pin

switch SW 1

stop

running

stopwatch

TSR2

INTA

open

closed

stopped

running

TSR2 = t4

TS pin sampled

vdd_int

floating

VSS

aaa-010561

Figure 37. Application example timing

• At and before t1, SW1 is open (TS pin floating). The TS pin is sampled and the internal

pull-up resistor will pull the pin HIGH to vdd_int. No actions are taken by the IC.

• At t2, SW1 is still open. No action is taken by the IC.

• At t3, SW1 closes. The TS pin is now shorted to VSS. The TS pin has not been sampled

yet, so no action is taken by the IC.

• At t4, SW1 is closed. The internal pull-up resistor is enabled, but TS pin remains LOW.

The pin is then sampled and the LOW level detected. As the TSL bit was set for active

LOW detection, the HIGH-LOW transition of TS pin sampled triggers an event.

STOPM mode was configured to allow the TS pin to stop the time counting. As the TSL

bit was set for active LOW, time counting stops when the TS pin is LOW.

Timestamp register 2 was configured to take a copy of the time on an event of the TS

pin, hence TSR2 loads the time t4. TSR2F is also set.

INTA was configured to generate an interrupt when TSR2 loads a new time, hence an

interrupt pulse is seen on INTA.

• At t5, SW1 is opened. No action is taken by the IC.

• At t6, SW1 is open. The internal pull-up is active and the TS pin raises to vdd_int level.

The HIGH level is sampled and causes the stop signal to be released and time starts

counting again.

PCF85263A

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

Product data sheet

Rev. 5 — 1 February 2021

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PCF85263ATL/A Datasheet(PDF) 62 Page - NXP Semiconductors

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