Rabbit Coyote BL2500, Руководство пользователя

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Coyote (BL2500)
B.2 Batteries and External Battery Connections
The SRAM and the real-time clock have battery backup. Power to the SRAM and the real-
time clock (VRAM) on the Coyote’s RabbitCore module is provided by two different
sources, depending on whether the main part of the Coyote is powered or not. When the
Coyote is powered normally, and Vcc is within operating limits, the SRAM and the real-
time clock are powered from Vcc. If power to the board is lost or falls below 2.93 V, the
VRAM and real-time clock power will come from the battery. The reset generator circuit
controls the source of power by way of its
/RESET output signal.
A soldered-in 1000 mA·h lithium battery provides power to the real-time clock and SRAM
when external power is removed from the circuit board. The drain on the battery is less than
10 µA when there is no external power applied to the Coyote, and so the expected shelf life
of the battery is more than
The drain on the battery is typically less than 4 µA when external power is applied, and so
the expected battery in-service life is
Since the nominal shelf life of the lithium battery is 10–20 years, the in-service life should
not be of concern.
NOTE: The SRAM contents and the real-time clock settings will be lost if the battery is
replaced with no power applied to the Coyote. Exercise care if you replace the battery
while external power is applied to the Coyote.
1000 mA·h
10 µA
--------------------------- 11.4 years. =
1000 mA·h
4 µA
--------------------------- 28 years. =