PCA2129T/Q900/2,51 NXP Semiconductors, PCA2129T/Q900/2,51 Datasheet - Page 15

• Manufacturer Part Number: PCA2129T/Q900/2,51
• Description: Real Time Clock
• Manufacturer: NXP Semiconductors
• Series: PCA2129r

Specifications of PCA2129T/Q900/2,51

• 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: 1.8 V
• Maximum Operating Temperature: + 80 C
• Minimum Operating Temperature: - 30 C
• Mounting Style: SMD/SMT
• Package / Case: SOP-16
• Battery Backup Switching: Yes

NXP Semiconductors
PCA2129T
Product data sheet
8.5.1 Battery switch-over function
8.5 Power management functions
The PCA2129T has two power supply pins and one power output pin:
The PCA2129T 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 PCA2129T 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 PCA2129T 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. 3 — 24 January 2013
DD
< V
Accurate RTC with integrated quartz crystal for automotive
DD
th(sw)bat
to V
BAT
without requiring V
DD
> 2.5 V.
DD
to drop below V
PCA2129T
© NXP B.V. 2013. All rights reserved.
DD
th(sw)bat
< V
DD
BAT
);
15 of 72
.
DD
.