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ADC121C021 Datasheet, PDF (1/30 Pages) National Semiconductor (TI) – I2C-Compatible, 12-Bit Analog-to-Digital Converter (ADC) with Alert Function
January 17, 2008
ADC121C021/ADC121C027
I2C-Compatible, 12-Bit Analog-to-Digital Converter (ADC)
with Alert Function
General Description
The ADC121C021 is a low-power, monolithic, 12-bit, analog-
to-digital converter(ADC) that operates from a +2.7 to 5.5V
supply. The converter is based on a successive approxima-
tion register architecture with an internal track-and-hold circuit
that can handle input frequencies up to 11MHz. The
ADC121C021 operates 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 ADC's Alert feature provides an interrupt that is activated
when the analog input violates a programmable upper or low-
er 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 mea-
sured voltage goes out-of-range.
The ADC121C021 comes in a small TSOT-6 package with an
alert output. The ADC121C027 comes in a small TSOT-6
package with an address selection input. The ADC121C027
provides three pin-selectable addresses. Pin-compatible al-
ternatives 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 tem-
perature range of −40°C to +105°C is guaranteed. Their low
power consumption and small packages make this family of
ADCs an excellent choice for use in battery operated equip-
ment.
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.
Features
■ 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 four pin-selectable chip addresses
■ Out-of-range Alert Function
■ Automatic Power-down mode while not converting
■ Very small 6-pin TSOT packages
■ ±8kV HBM ESD protection (SDA, SCL)
Key Specifications
■ Resolution
12 bits; no missing codes
■ Conversion Time
1µs (typ)
■ INL & DNL
±1 LSB (max) (up to 22kSPS)
■ Throughput Rate
188.9kSPS (max)
■ Power Consumption (at 22kSPS)
— 3V Supply
0.26 mW (typ)
— 5V Supply
0.78 mW (typ)
Applications
■ System Monitoring
■ Peak Detection
■ Portable Instruments
■ Medical Instruments
■ Test Equipment
Pin-Compatible Alternatives
All devices are fully pin and function compatible.
Resolution ALERT Output
ADDR Input
12-bit
ADC121C021
ADC121C027
10-bit
ADC101C021
ADC101C027
8-bit
ADC081C021
ADC081C027
Connection Diagrams
30020901
I2C® is a registered trademark of Phillips Corporation.
© 2008 National Semiconductor Corporation
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