pcf2127a NXP Semiconductors, pcf2127a Datasheet - Page 24

• Manufacturer Part Number: pcf2127a
• Description: Integrated Rtc, Tcxo And Quartz Crystal
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF2127A_1
Product data sheet
8.6.4.2 Extra power fail detection when the battery switch-over function is disabled
If the battery switch-over function is disabled and the power fail comparator is enabled,
the power fail output at pin PFO depends only on the results of the comparison between
V
Fig 11. PFO signal behavior when battery switch-over is enabled in direct switching
Fig 12. PFO signal behavior when battery switch-over is disabled
PFI
•
•
V
comparator
V
DD
(= 2.5 V)
enabled
V
th(sw)bat
(= 2.5 V)
V
If V
If V
th(sw)bat
V
and 1.25 V:
th(uvp)
(= 0 V)
th(uvp)
V
PF0
V
V
PF0
DD
BAT
PFI
PFI
DD
mode and V
> 1.25 V, PFO = HIGH (through the external pull-up resistor)
< 1.25 V, PFO = LOW
V
BBS
th(uvp)
Rev. 01 — 21 January 2010
< V
BAT
internal power supply (= V
comparator always enabled
comparator
disabled
Integrated RTC, TCXO and quartz crystal
BBS
)
PCF2127A
© NXP B.V. 2010. All rights reserved.
t
rec
V
BBS
comparator
001aaj321
enabled
001aaj320
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