adc081c027cimkx National Semiconductor Corporation, adc081c027cimkx Datasheet - Page 22

• Manufacturer Part Number: adc081c027cimkx
• Description: I2c-compatible, 12-bit Analog-to-digital Converter Adc With Alert Function
• Manufacturer: National Semiconductor Corporation

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The Under Range Alert condition is cleared when one of the
following two conditions is met:
1.
2.
If the alert condition has been cleared by writing a one to the
alert flag while the measured voltage still violates the V
or V
completion of the next conversion (see Figure 10).
Alert conditions only occur if the input voltage exceeds the
V
instant. The input voltage can exceed the V
below the V
causing an alert condition.
FIGURE 10. Alert condition cleared by writing a "1" to the
HIGH
FIGURE 9. Alert condition cleared when measured
LOW
The controller writes a one to the Under Range Alert Flag
bit.
The measured voltage goes above the programmed
V
Alert Hold bit is cleared in the Configuration register. If
the Alert Hold bit is set, the alert condition persists and
only clears when a one is written to the Under Range
Alert Flag bit.
LOW
limit or falls below the V
limits, an alert condition will occur again after the
limit plus the programmed V
LOW
voltage crosses V
limit briefly between conversions without
Alert Flag.
LOW
HIGH
limit at the sample-hold
HYST
- V
HYST
value and the
HIGH
limit or fall
30052174
30052175
HIGH
22
1.9 AUTOMATIC CONVERSION MODE
The automatic conversion mode configures the ADC to con-
tinually perform conversions without receiving "read" instruc-
tions from the controller over the I
activated by writing a non-zero value into the Cycle Time bits
- D[7:5] - of the Configuration register (see Section 1.6.4 Con-
figuration Register). Once the ADC081C021 enters this
mode, the internal oscillator is always enabled. The ADC's
control logic samples the input at the sample rate set by the
cycle time bits. Although the conversion result is not trans-
mitted by the 2-wire interface, it is stored in the conversion
result register and updates the various status registers of the
device.
In automatic conversion mode, the out-of-range alert function
is active and updates after every conversion. The ADC can
operate independently of the controller in automatic conver-
sion mode. When the input signal goes "out-of-range", an
alert signal is sent to the controller. The controller can then
read the status registers and determine the source of the alert
condition. Also, comparison and updating of the V
V
conversion mode. The controller can occasionally read the
V
extremes. These register values persist until the user resets
the V
system monitoring, peak detection, and sensing applications.
MAX
MIN
MIN
and/or V
registers occurs after every conversion in automatic
and V
MAX
MAX
registers to determine the sampled input
registers. These two features are useful in
2
C interface. The mode is
MIN
and