1FEATURES
23• I2C-Compatible 2-Wire Interface Which
Supports Standard (100kHz), Fast (400kHz),
and High Speed (3.4MHz) Modes
• Extended Power Supply Range (+2.7V to
+5.5V)
• Up to Nine Pin-Selectable Chip Addresses
(VSSOP Only)
• Out-of-Range Alert Function
• Automatic Power-Down Mode while Not
Converting
• Very Small 6-Pin SOT and 8-Pin VSSOP
Packages
• ADC121C021Q is an Automotive Grade
Product that is AEC-Q100 Grade 2 Qualified

APPLICATIONS
• System Monitoring
• Peak Detection
• Portable Instruments
• Medical Instruments
• Test Equipment
• Automotive

KEY SPECIFICATIONS
• Resolution: 12 Bits (No Missing Codes)
• Conversion Time: 1μs (Typ)
• INL & DNL: ±1 LSB (Max) (Up to 22ksps)
• Throughput Rate: 188.9 ksps (Max)
• Power Consumption (at 22 ksps)
– 3V Supply: 0.26 mW (Typ)
– 5v Supply: 0.78 mW (Typ)

DESCRIPTION
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 I2Ccompatible
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.