PCF2131 datasheet(15/85 Pages) NXP

15 / 85 page

NXP Semiconductors

PCF2131

Nano-power highly accurate RTC with integrated quartz crystal

TCR[1:0]

Temperature measurement period

[1] 32 min

16 min

8 min

4 min

Table 17. Temperature measurement period

[1]

Default value.

7.3.2 OTP refresh

Each IC is calibrated during production and testing of the device. The calibration parameters are stored on

EPROM cells called One Time Programmable (OTP) cells. It is recommended to process an OTP refresh once

after the power is up and the oscillator is operating stable. The OTP refresh takes less than 100 ms to complete.

To perform an OTP refresh, bit OTPR has to be cleared (set to logic 0) and then set to logic 1 again.

When read OTPR bit, its state is:

"0" until the OTP read state machine completes copying of the eFuse data into the shadow registers. This could

be due to a POR event or to writing a 0 > 1 to the OTPR register bit.

"1" when the OTP read state machine completes copying to the shadow registers from the eFuse instances.

During normal operation OTPR must be kept at 1 to prevent higher power usage.

The OTP logic is not reset nor affected by the Software Reset. The OTPR functionality is only reset by the initial

digital POR.

During OTP refresh, VDD has to be above 1.8 V, the rising speed to 1.8 V needs to be faster than 2 V/100 ms.

After OTP refresh has finished, PCF2131 can operate with VDD as low as 1.2 V.

7.3.3 Clock output

A programmable square wave is available at pin CLKOUT. Operation is controlled by the COF[2:0] control

bits in register CLKOUT_ctl. Frequencies of 32.768 kHz (default) down to 1 Hz can be generated for use as

system clock, microcontroller clock, charge pump input, or for calibrating the oscillator at 25 °C to determine

aging offset. The CLKOUT output is not temperature compensated to prevent jitter due to digital compensation

method.

CLKOUT is a push-pull output and is enabled at power-on. When disabled, the output is high-impedance.

COF[2:0]

CLKOUT frequency (Hz)

Typical duty cycle [1]

000

[2] 32 768

60 : 40 to 40 : 60

001

16 384

50 : 50

010

8 192

50 : 50

011

4 096

50 : 50

100

2 048

50 : 50

101

1 024

50 : 50

110

50 : 50

111

CLKOUT = high-Z

Table 18. CLKOUT frequency selection

PCF2131

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

Product data sheet

Rev. 2.0 — 5 October 2023

15 / 85

PCF2131 Datasheet(PDF) 15 Page - NXP Semiconductors

PCF2131 Datasheet(HTML) 15 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85

Datasheet Download

Link URL