PCF2129AT/2,518 NXP Semiconductors, PCF2129AT/2,518 Datasheet - Page 14

• Manufacturer Part Number: PCF2129AT/2,518
• Description: Real Time Clock
• Manufacturer: NXP Semiconductors
• Series: PCF2129r

Specifications of PCF2129AT/2,518

• Rohs: yes
• Function: Clock, Calendar, Alarm, Watchdog, Timestamp
• Rtc Bus Interface: I2C, SPI
• Date Format: Binary
• Time Format: Binary
• Supply Voltage - Max: 4.2 V
• Supply Voltage - Min: 1.2 V
• Maximum Operating Temperature: + 60 C
• Minimum Operating Temperature: - 15 C
• Mounting Style: SMD/SMT
• Package / Case: SOP-20
• Battery Backup Switching: Yes
• Factory Pack Quantity: 2000

NXP Semiconductors
PCF2129AT
Product data sheet
8.5.1 Battery switch-over function
8.5 Power management functions
The PCF2129AT has two power supply pins and one power output pin:
The PCF2129AT has two power management functions implemented:
The power management functions are controlled by the control bits PWRMNG[2:0] in
register Control_3:
Table 14.
[1]
[2]
The PCF2129AT has a backup battery switch-over circuit which monitors the main power
supply V
backup battery.
One of two operation modes can be selected:
PWRMNG[2:0]
000
001
010
011
100
101
111
•
•
•
•
•
•
•
V
V
BBS - battery backed output voltage pin (equal to the internal power supply)
Battery switch-over function
Battery low detection function
Default value.
When the battery switch-over function is disabled, the PCF2129AT works only with the power supply V
V
Standard mode: the power failure condition happens when:
V
V
switch-over in standard mode works only for V
Direct switching mode: the power failure condition happens when V
Direct switching from V
BAT
DD
BAT
DD
th(sw)bat
must be put to ground and the battery low detection function is disabled.
- the main power supply input pin
DD
< V
- the battery backup input pin
Power management control bit description
. When a power failure condition is detected, it automatically switches to the
BAT
is the battery switch threshold voltage. Typical value is 2.5 V. The battery
All information provided in this document is subject to legal disclaimers.
AND V
[1]
[2]
Function
battery switch-over function is enabled in standard mode;
battery low detection function is enabled
battery switch-over function is enabled in standard mode;
battery low detection function is disabled
battery switch-over function is enabled in standard mode;
battery low detection function is disabled
battery switch-over function is enabled in direct switching mode;
battery low detection function is enabled
battery switch-over function is enabled in direct switching mode;
battery low detection function is disabled
battery switch-over function is enabled in direct switching mode;
battery low detection function is disabled
battery switch-over function is disabled, only one power supply (V
battery low detection function is disabled
Rev. 5 — 12 February 2013
DD
< V
DD
th(sw)bat
to V
BAT
without requiring V
Integrated RTC, TCXO and quartz crystal
DD
> 2.5 V.
DD
to drop below V
PCF2129AT
© NXP B.V. 2013. All rights reserved.
DD
th(sw)bat
< V
DD
BAT
);
14 of 73
.
DD
;