ADC121C021CIMKX/NOPB National Semiconductor, ADC121C021CIMKX/NOPB Datasheet - Page 23

• Manufacturer Part Number: ADC121C021CIMKX/NOPB
• Description: IC ADC 12BIT I2C ALERT TSOT-23-6
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of ADC121C021CIMKX/NOPB

• Number Of Bits: 12
• Sampling Rate (per Second): 188.9k
• Data Interface: I²C, Serial
• Number Of Converters: 1
• Power Dissipation (max): 780µW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6 Thin, TSOT-23-6
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADC121C021CIMKX

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
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
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.
limit or falls below the V
limits, an alert condition will occur again after the
LOW
voltage crosses V
limit briefly between conversions without
Alert Flag.
LOW
HIGH
limit at the sample-hold
- V
Figure
HYST
HIGH
10).
limit or fall
30020974
30020975
HIGH
23
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
figuration
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.
1.10 COMMUNICATING WITH THE ADC121C021
The ADC121C021's data registers are selected by the ad-
dress pointer (see Section
To read/write a specific data register, the pointer must be set
to that register's address. The pointer is always written at the
beginning of a write operation. When the pointer needs to be
updated for a read cycle, a write operation must precede the
read operation to set the pointer address correctly. On the
other hand, if the pointer is preset correctly, a read operation
can occur without writing the address pointer register. The
following timing diagrams describe the various read and write
operations supported by the ADC.
MAX
MIN
MIN
and/or V
registers occurs after every conversion in automatic
and V
Register). Once the ADC121C021 enters this
MAX
MAX
registers to determine the sampled input
registers. These two features are useful in
1.6.1 Address Pointer
2
C interface. The mode is
www.national.com
1.6.4 Con-
Register).
MIN
and