PCF2129AT datasheet(22/86 Pages) PHILIPS

номер детали	PCF2129AT

подробное описание детали	Accurate RTC with integrated quartz crystal for industrial applications

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производитель	PHILIPS [NXP Semiconductors]

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PCF2129

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Product data sheet

Rev. 7 — 19 December 2014

22 of 86

NXP Semiconductors

PCF2129

Accurate RTC with integrated quartz crystal for industrial applications

8.6 Oscillator stop detection function

The PCF2129 has an on-chip oscillator detection circuit which monitors the status of the

oscillation: whenever the oscillation stops, a reset occurs and the oscillator stop flag OSF

(in register Seconds) is set logic 1.

• Power-on:

a. The oscillator is not running, the chip is in reset (OSF is logic 1).

b. When the oscillator starts running and is stable after power-on, the chip exits from

reset.

c. The flag OSF is still logic 1 and can be cleared (OSF set logic 0) by command.

• Power supply failure:

a. When the power supply of the chip drops below a certain value (Vlow), typically

1.2 V, the oscillator stops running and a reset occurs.

b. When the power supply returns to normal operation, the oscillator starts running

again, the chip exits from reset.

c. The flag OSF is still logic 1 and can be cleared (OSF set logic 0) by command.

Fig 10. Typical driving capability of VBBS: (VBBS  VDD) with respect to the output load

current IBBS

PCF2129AT датащи(PDF) 22 Page - NXP Semiconductors