PCF2129 datasheet(19/86 Pages) PHILIPS

tên linh kiện	PCF2129

Giải thích chi tiết về linh kiện	Accurate RTC with integrated quartz crystal for industrial applications

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PCF2129

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Product data sheet

Rev. 7 — 19 December 2014

19 of 86

NXP Semiconductors

PCF2129

Accurate RTC with integrated quartz crystal for industrial applications

8.5.1.2

Direct switching mode

If VDD > VBAT: Voper(int) is at VDD potential.

If VDD < VBAT: Voper(int) is at VBAT potential.

The direct switching mode is useful in systems where VDD is always higher than VBAT.

This mode is not recommended if the VDD and VBAT values are similar (for example,

VDD = 3.3 V, VBAT  3.0 V). In direct switching mode, the power consumption is reduced

compared to the standard mode because the monitoring of VDD and Vth(sw)bat is not

performed.

8.5.1.3

Battery switch-over disabled: only one power supply (VDD)

When the battery switch-over function is disabled:

• The power supply is applied on the VDD pin

• The VBAT pin must be connected to ground

• Voper(int) is at VDD potential

• The battery flag (BF) is always logic 0

Fig 7.

Battery switch-over behavior in direct switching mode with bit BIE set logic 1

(enabled)

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