These converters are low-power, monolithic, 12-bit, analog-to-digital converters (ADCs)
that operates from a +2.7 to 5.5V supply. The converter is based upon a successive approximation
register architecture with an internal track-and-hold circuit that can handle input frequencies up
to 11MHz. These converters operate from a single supply which also serves as the reference. The
device features an I2C-compatible serial interface that operates in all
three speed modes, including high speed mode (3.4MHz).
The ADC121C021's Alert feature provides an interrupt that is activated when the analog
input violates a programmable upper or lower limit value. The device features an automatic
conversion mode, which frees up the controller and I2C interface. In
this mode, the ADC continuously monitors the analog input for an "out-of-range" condition and
provides an interrupt if the measured voltage goes out-of-range.
The ADC121C021 comes in two packages: a small 6-pin SOT package with an alert output,
and an 8-pin VSSOP package with an alert output and two address selection inputs. The ADC121C021Q
is available in a 6-pin SOT package. The ADC121C027 comes in a small 6-pin SOT package with an
address selection input. The ADC121C027 provides three pin-selectable addresses while the 8-pin
VSSOP version of the ADC121C021 provides nine pin-selectable addresses. Pin-compatible alternatives
to the 6-pin SOT options are available with additional address options.
Normal power consumption using a +3V or +5V supply is 0.26mW or 0.78mW, respectively.
The automatic power-down feature reduces the power consumption to less than 1µW while not
converting. Operation over the industrial temperature range of −40°C to +105°C is ensured. Their
low power consumption and small packages make this family of ADCs an excellent choice for use in
battery operated equipment.
The ADC121C021 and ADC121C027 are part of a family of pin-compatible ADCs that also
provide 8 and 10 bit resolution. For 8-bit ADCs see the ADC081C021 and ADC081C027. For 10-bit ADCs
see the ADC101C021 and ADC101C027.