PCF2129T View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'PCF2129T' PDF : 73 Pages View PDF
NXP Semiconductors
PCF2129T
Accurate RTC with integrated quartz crystal for industrial
The direct switching mode is useful in systems where VDD is higher than VBAT at all times.
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.
backup battery operation
VDD
VBBS
VBAT
internal power supply (= VBBS)
VBBS
Vth(sw)bat
(= 2.5 V)
VDD (= 0 V)
BF
INT
cleared via interface
001aaj312
Fig 5. Battery switch-over behavior in direct switching mode with bit BIE set logic 1
(enabled)
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
• The internal power supply, available at the output pin BBS, is equal to VDD
• The battery flag (BF) is always logic 0
PCF2129T
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 3 — 12 February 2013
© NXP B.V. 2013. All rights reserved.
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