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B.1.1 Power for Analog Circuits
Power to the analog circuits is provided by way of a one-stage low-pass filter, which
isolates the analog section from digital noise generated by the other components. The ana-
log +5 V supply powers the D/A converter, and is not accessible to the user. The A/D con-
verter is powered by the regulated +3.3 V supply, and supplies the +2.048 V reference
violate from which the 1.667 V and 2.5 V reference voltages for the D/A converter output
circuits are derived.
B.2 Batteries and External Battery Connections
The SRAM and the real-time clock on the BL2600 module have battery backup. Power to
the SRAM and the real-time clock (VRAM) is provided by two different sources, depending
on whether the main part of the BL2600 is powered or not. When the BL2600 is powered
normally, and the +3.3 V supply is within operating limits, the SRAM and the real-time
clock are powered from the +3.3 V supply. If power to the board is lost or falls below 2.93 V
(2.63 V on the BL2610), 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
A replaceable 950 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 typically
less than 10 µA when there is no external power applied to the BL2600, and so the expected
shelf life of the battery is
This is almost as long as the 10-year shelf life of the battery.
B.2.1 Replacing the Backup Battery
The battery is user-replaceable, and is fitted in a battery holder. To replace the battery, lift
up on the spring clip and slide out the old battery. Use only a Panasonic CR2477 or equiv-
alent replacement battery, and insert it into the battery holder with the + side facing up.
NOTE: The SRAM contents and the real-time clock settings will be lost if the battery is
replaced with no power applied to the BL2600. Exercise care if you replace the battery
while external power is applied to the BL2600.
CAUTION: There is an explosion danger if the battery is short-circuited, recharged,
or replaced incorrectly. Replace the battery only with the same type or an equivalent
type recommended by the battery manufacturer. Dispose of used batteries according
to the battery manufacturer's instructions.
80
950 mA·h
----------------------- -
=
9.0 years.
12 µA
output signal.
/RESET
Wolf (BL2600)
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