PCF8523 NXP [NXP Semiconductors], PCF8523 Datasheet - Page 14

• Manufacturer Part Number: PCF8523
• Description: Real-Time Clock (RTC) and calendar
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCF8523
Product data sheet
8.5.1 Standby mode
8.5 Power management functions
The PCF8523 has two power supply pins:
The PCF8523 has two power management functions implemented:
The power management functions are controlled by the control bits PM[2:0] in register
Control_3 (02h):
Table 9.
[1]
[2]
When the device is first powered up from the battery (V
(V
PCF8523 will not draw any power from the backup battery until the device is powered up
from the main power supply V
mode whenever the main power supply V
It is also possible to enter into standby mode when the chip is already supplied by main
power supply V
power management control bits PM[2:0] have to be set logic 111. Then the main power
supply V
and will not draw any current from the backup battery before it is powered up again from
main supply V
PM[2:0]
000
001
010
100
101
110
111
•
•
•
•
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[1][2]
[1]
V
V
Battery switch-over function,
Battery low detection function.
When the battery switch-over function is disabled, the PCF8523 works only with the power supply V
V
Default value.
), the PCF8523 automatically enters the standby mode. In standby mode the
BAT
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BAT
must be put to ground and the battery low detection function is disabled.
- the main power supply input pin,
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- the battery backup input pin.
Power management function control bits
must be removed, as a result of this the PCF8523 will enter the standby mode
Function
battery switch-over function is enabled in standard mode;
battery low detection function is enabled
battery switch-over function is enabled in direct switching mode;
battery low detection function is enabled
battery switch-over function is disabled - only one power supply (V
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 direct switching mode;
battery low detection function is disabled
not allowed
battery switch-over function is disabled - only one power supply (V
battery low detection function is disabled
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All information provided in this document is subject to legal disclaimers.
.
and a backup battery is connected. To enter the standby mode, the
Rev. 3 — 30 March 2011
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. Thereafter, the device will switch over to battery backup
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is lost.
Real-Time Clock (RTC) and calendar
BAT
) but without a main supply
PCF8523
© NXP B.V. 2011. All rights reserved.
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