PCF2127AT/1 NXP [NXP Semiconductors], PCF2127AT/1 Datasheet - Page 24

• Manufacturer Part Number: PCF2127AT/1
• Description: Integrated RTC, TCXO and quartz crystal
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCF2127A_2
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 result 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
All information provided in this document is subject to legal disclaimers.
BBS
th(uvp)
Rev. 02 — 7 May 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
24 of 80