PCF2131 datasheet(17/85 Pages) NXP

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NXP Semiconductors

PCF2131

Nano-power highly accurate RTC with integrated quartz crystal

AO[3:0]

Decimal

Binary

ppm

1010

-4

1011

-6

1100

-8

1101

-10

1110

-12

1111

-14

Table 21. Frequency correction at 25 °C, typical...continued

[1]

Default value.

7.5 Power management functions

The PCF2131 has two power supplies:

VDD - the main power supply

VBAT - the battery backup supply

Internally, PCF2131 operates with the internal operating voltage Voper(int) which is also available as VBBS on the

battery backed output voltage pin, BBS. Depending on the condition of the main power supply and the selected

power management function, Voper(int) is either on the potential of VDD or VBAT.

Two power management functions are implemented:

Battery switch-over function - monitors the main power supply VDD and switching to VBAT in case a power fail

condition is detected (see Section 7.5.1).

Battery low detection function - monitors the status of the battery, VBAT (see Section 7.5.2).

The power management functions are controlled by the control bits PWRMNG[2:0] (see Table 22) in register

Control_3 (see Table 10):

PWRMNG[2:0]

Function

000

battery switch-over function is enabled in standard mode;

battery low detection function is enabled

001,010

battery switch-over function is enabled in standard mode;

battery low detection function is disabled

011

battery switch-over function is enabled in direct switching mode;

battery low detection function is enabled

100,101

battery switch-over function is enabled in direct switching mode;

battery low detection function is disabled

110,111

[1] [2] battery switch-over function is disabled, only one power supply (VDD);

battery low detection function is disabled

Table 22. Power management control bit description

[1]

Default value.

[2]

When the battery switch-over function is disabled, the device works only with the power supply VDD. VBAT must be put to ground and the battery low

detection function is disabled.

PCF2131

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

Product data sheet

Rev. 2.0 — 5 October 2023

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