Low Battery Detect (LBD) - Low Voltage Reset
110
PRELIMINARY V1.8
19. Low Battery Detect (LBD) - Low Voltage Reset
19.1.
General Information
The low battery detect and low voltage reset circuit has two main functions.
• Used as a low battery detector, the circuit will detect the Vcc of the SS1102C falling
below the selected programmable level of 2.9, 2.8 or 2.7 volts. Once detected, the
circuit will send an interrupt to the SS1102C interrupt block.
• For non-battery usage the circuit can be programmed to detect Vcc falling below 2.6
volts and provide a hardware reset to the SS1102C, thus protecting the user from
getting corrupted data on chip from power supply glitches below the 2.6 volt, mini-
mum voltage level.
19.2.
Functional Description
The low battery detect and low voltage reset circuit uses a programmable resistor ladder
to sense the variation of the power supply Vcc. The sensed voltage is compared against
a reference voltage generated on chip. The output of the comparator is used to provide
an interrupt signal for the low battery detect function or the reset for the low voltage
reset function. The selection of low battery detect thresholds or the low voltage reset is
controlled by the microprocessor.
Once a low battery detect threshold has been detected, the circuit could be
reprogrammed by the software to use the next lower voltage threshold.
The circuit may be disabled to save power between readings or when not required for a
particular application.
supply voltage (Vdd)
2.7 - 3.3V and
4.5 - 5.5V
current enable mode
max. 28uA at 3.3V and
max.
41uA at 5.5V supply
current disable mode
3nA at 3.3V and
83nA at 5.5V
temperature range
-20 to +85
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