Part A
ADC121S021CIMF
Texas Instruments
- Lifecycle
- Active
- Stock
- 6879 PCS
- Package
- SOT-23-6
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Not a drop-in replacement
The ADC121S021CIMF and ADC121C021CIMK are not drop-in replacements for each other. Although both are 12-bit, single-channel analog-to-digital converters from Texas Instruments, they differ in package footprint, pin configuration, and digital interface, so a direct board-level substitution is not possible without layout and interface changes.
Different package footprint
Different pin configuration
Different digital interface
Different supply voltage range
Parts at a glance
Part B
ADC121C021CIMK
Texas Instruments
- Lifecycle
- Active
- Stock
- 5279 PCS
- Package
- TSOT-23-6
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADC121S021CIMF | ADC121C021CIMK | Why it matters |
|---|---|---|---|
| Resolution | 12 bit | 12 bit | Both provide 12-bit resolution, so conversion precision is equivalent for signal acquisition. |
| Interface Type | SPI | I2C | The digital interface differs, so the host microcontroller must support the corresponding bus; this is a key barrier to direct substitutability. |
| Number of Input Channels | 1 | 1 | Both are single-channel devices, so channel count is not a differentiator for single-signal applications. |
| Input Type | Single-ended | Single-ended | Both accept single-ended inputs, matching the same signal conditioning approach. |
| Supply Voltage Range | 2.7 V to 5.25 V | 2.7 V to 5.25 V | Identical supply range means both can operate from the same system rail without level shifting. |
| Package / Mounting | SOT-23-6, Surface Mount | SOT-23-6, Surface Mount | Same package and mounting allow a shared PCB footprint, easing board-level substitution. |
| Sampling Rate | 200 kSPS | 188.9 kSPS | Slightly different maximum throughput affects how fast the signal can be sampled in time-sensitive designs. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature ratings mean both suit the same industrial and commercial environments. |
| Reference Type | Supply-referenced | Supply-referenced | Both use the supply as reference, so accuracy depends similarly on supply stability. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADC121S021CIMF | ADC121C021CIMK |
|---|---|---|
| Supplier | - | Texas Instruments |
| Part Status | Not For New Designs | Obsolete |
| Number of Bits | 12 | 12 |
| Sampling Rate(Per Second) | 200k | 188.9k |
| Number of Inputs | 1 | 1 |
| Input Type | Single Ended | Single Ended |
| Data Interface | SPI, DSP | I²C |
| Configuration | S/H-ADC | S/H-ADC |
| Ratio - S / H: ADC | 1:1 | 1:1 |
| Number of A/D Converters | 1 | 1 |
| Architecture | SAR | SAR |
| Reference Type | Supply | Supply |
| Voltage - Supply, Analog | 2.7V ~ 5.25V | 2.7V ~ 5.5V |
| Voltage - Supply, Digital | 2.7V ~ 5.25V | 2.7V ~ 5.5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 105°C |
Frequently asked questions
What are the key differences between the ADC121S021CIMF and ADC121C021CIMK?
The ADC121S021CIMF is a 12-bit, 1 MSPS successive-approximation ADC with a single-ended input and an SPI-compatible serial interface, supplied in a 6-pin SOT-23 package. The ADC121C021CIMK is a 12-bit, 188.9 kSPS ADC with an I2C-compatible two-wire interface, supplied in a 6-pin SOT-23 package. The primary differences are the digital interface (SPI vs I2C), the maximum sample rate (1 MSPS vs 188.9 kSPS), and the corresponding package pinout.
Are the ADC121S021CIMF and ADC121C021CIMK pin-compatible?
No. Although both devices are offered in a 6-pin SOT-23 package, their pin functions differ because one uses an SPI interface and the other uses an I2C interface. The ADC121S021CIMF pinout includes CS, SCLK, and SDATA for SPI, while the ADC121C021CIMK pinout includes SDA and SCL for I2C. A direct drop-in replacement on the same PCB land pattern is therefore not possible without verifying pin functions against the respective datasheets.
Can the ADC121S021CIMF be substituted with the ADC121C021CIMK in an existing design?
Not directly. Substitution requires validating the interface change from SPI to I2C, confirming the host controller supports I2C at the required bus speed, verifying the reduced maximum sample rate of 188.9 kSPS is acceptable for the application, and checking that the pinout and PCB layout are compatible. All differences must be validated against the manufacturer datasheets before substitution.
What is the maximum sample rate of each device?
The ADC121S021CIMF supports a maximum throughput of 1 MSPS. The ADC121C021CIMK supports a maximum throughput of 188.9 kSPS. The sample rate difference is a direct consequence of the interface: the SPI interface of the ADC121S021CIMF allows higher throughput than the I2C interface of the ADC121C021CIMK.
What digital interfaces do these two ADCs use?
The ADC121S021CIMF uses an SPI-compatible serial interface with chip select (CS), serial clock (SCLK), and serial data (SDATA) signals. The ADC121C021CIMK uses an I2C-compatible two-wire interface with serial data (SDA) and serial clock (SCL) signals. The interface choice affects host controller requirements, bus topology, and achievable throughput.
What is the resolution and input type of both devices?
Both the ADC121S021CIMF and ADC121C021CIMK are 12-bit ADCs with a single-ended analog input. Both are successive-approximation register (SAR) converters. Resolution and input configuration are therefore equivalent between the two parts; the differences lie in interface, sample rate, and pinout.
What package do the ADC121S021CIMF and ADC121C021CIMK use?
Both devices are supplied in a 6-pin SOT-23 package. Despite the common package type, the pin assignments differ between the SPI and I2C variants, so PCB land patterns and signal routing must be verified against the respective datasheets before any layout reuse.
Which device should be selected for a high-throughput application?
For applications requiring higher throughput, the ADC121S021CIMF is the appropriate choice because its SPI interface supports up to 1 MSPS. The ADC121C021CIMK, limited to 188.9 kSPS by its I2C interface, is better suited to lower-speed, multi-device bus architectures where I2C addressing and reduced pin count are advantageous.