pcf2127a NXP Semiconductors, pcf2127a Datasheet - Page 20

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

NXP Semiconductors
PCF2127A_1
Product data sheet
8.6.2 Battery backup supply
The internal power supply (available on pin BBS) is equal to V
assured that there are decoupling capacitors on the pins V
The V
on the selected battery switch-over function mode:
Table 18.
The output pin BBS can be used as a supply for external devices with battery backup
needs (see
when V
Battery switch-over function mode
standard
direct switching
disabled
Fig 6.
BBS
BBS
Battery switch-over circuit, simplified block diagram
voltage on the output pin BBS is equal to the internal power supply and depends
Output pin BBS
is driven from V
Ref. 3
V
V
th(sw)bat
th(sw)bat
V
V
BAT
DD
“AN10857”). For this case,
Rev. 01 — 21 January 2010
comparators
V
V
CC
CC
DD
.
LOGIC
Conditions
V
V
V
V
V
only V
DD
DD
DD
DD
BAT
logic
> V
< V
> V
< V
must be put to ground
DD
Figure 7
V
Integrated RTC, TCXO and quartz crystal
BAT
BAT
BAT
BAT
DD(int)
V
available,
V
BAT
DD
OR V
AND V
shows the typical driving capability
DD
DD
switches
V
V
> V
DD(int)
DD(int)
DD
< V
th(sw)bat
, V
th(sw)bat
DD
BAT
or V
(internal
power supply)
, and BBS.
PCF2127A
V
BAT
BBS
001aag061
© NXP B.V. 2010. All rights reserved.
. It has to be
V
V
V
V
V
V
BBS
DD
BAT
DD
BAT
DD
equals
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