Part A
ADC121S051CIMF
德州儀器
- Lifecycle
- Active
- Stock
- 1513 件
- Package
- SOT-23-6
- Series
- 資料獲取-模數轉換器（ADC）
Replacement verdict
Not a drop-in replacement
The ADC121S051CIMF and ADC121C021CIMK are not drop-in replacements for each other. Although both are 12-bit successive-approximation ADCs from Texas Instruments, they differ in resolution-related architecture, channel count, digital interface, and package footprint, so a direct board-level substitution is not possible without design changes.
Different channel count
Different digital interface
Different package footprint
Different conversion architecture
Parts at a glance
Part B
ADC121C021CIMK
德州儀器
- Lifecycle
- Active
- Stock
- 5279 件
- Package
- TSOT-23-6
- Series
- 資料獲取-模數轉換器（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 | ADC121S051CIMF | ADC121C021CIMK | Why it matters |
|---|---|---|---|
| Resolution | 12 bit | 12 bit | Both provide 12-bit resolution, so measurement granularity is equivalent for substitutability. |
| Number of Input Channels | 1 single-ended | 1 single-ended | Both are single-channel devices, so channel count does not differentiate them for a given signal path. |
| Sampling Rate | 500 kSPS | 188.9 kSPS | The higher conversion rate of the ADC121S051CIMF supports faster signal acquisition, which matters for higher-bandwidth signals. |
| Interface Type | SPI (serial) | I2C (2-wire) | Different digital interfaces require different host controller peripherals and firmware, directly affecting drop-in substitutability. |
| Supply Voltage Range | 2.7 V to 5.25 V | 2.7 V to 5.5 V | Slightly different upper supply limits affect compatibility with 5 V systems and margin at the high end of the rail. |
| Package / Mounting | SOT-23-6 (surface mount) | SOT-23-6 (surface mount) | Identical package and footprint allow the same PCB land pattern, easing physical replacement. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Matching industrial temperature ranges mean both suit the same environmental conditions. |
| Reference Type | Supply-referenced (VDD) | Supply-referenced (VDD) | Both use the supply as reference, so ratiometric behavior and full-scale accuracy depend similarly on supply stability. |
| Power Consumption | Low power (approx. 1 mW at 3 V) | Low power (approx. 1 mW at 3 V) | Comparable low power draw makes both suitable for battery-powered and energy-sensitive designs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADC121S051CIMF | ADC121C021CIMK |
|---|---|---|
| Supplier | - | Texas Instruments |
| Part Status | Obsolete | Obsolete |
| Number of Bits | 12 | 12 |
| Sampling Rate(Per Second) | 500k | 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 ADC121S051CIMF and ADC121C021CIMK?
The ADC121S051CIMF is a 12-bit, 500 kSPS to 1 MSPS successive-approximation ADC with a SPI-compatible serial interface, supplied in a SOT-23-6 package. The ADC121C021CIMK is a 12-bit, 188.9 kSPS I2C-compatible ADC with an alert function, supplied in a SOT-23-6 package. The primary differences are resolution-compatible but interface type (SPI vs I2C), throughput (up to 1 MSPS vs 188.9 kSPS), and the I2C device's programmable alert output.
Are the ADC121S051CIMF and ADC121C021CIMK pin-compatible?
No. Although both are offered in a 6-pin SOT-23 package, their pin functions differ because one uses a SPI interface and the other uses an I2C interface. The ADC121S051CIMF provides CS, SCLK, SDATA, and VA pins, while the ADC121C021CIMK provides SDA, SCL, and ALERT pins. They are not direct drop-in replacements.
What is the maximum sampling rate of each device?
The ADC121S051CIMF supports throughput up to 1 MSPS at its rated supply and clock conditions. The ADC121C021CIMK supports a maximum conversion rate of 188.9 kSPS. The SPI device is therefore suitable for higher-speed acquisition, while the I2C device suits lower-speed, bus-based monitoring.
What supply voltage range do these ADCs require?
Both devices operate from a single analog supply in the 2.7 V to 5.5 V range, per the manufacturer datasheets. This allows operation from common 3.3 V and 5 V rails. Always confirm the exact recommended operating conditions in the respective datasheet before design.
How does the digital interface differ between the two parts?
The ADC121S051CIMF uses a SPI-compatible serial interface with chip select, serial clock, and serial data lines, supporting direct connection to most microcontrollers and DSPs. The ADC121C021CIMK uses an I2C-compatible two-wire interface with SDA and SCL, plus a dedicated ALERT output for out-of-range detection. The choice depends on the host system's available bus and required data rate.
Does the ADC121C021CIMK offer any feature not present on the ADC121S051CIMF?
Yes. The ADC121C021CIMK includes a programmable alert function with an ALERT output that can be configured to signal when a conversion result crosses user-defined thresholds. The ADC121S051CIMF does not include this alert feature. This makes the I2C device advantageous for autonomous monitoring applications.
Can the ADC121S051CIMF and ADC121C021CIMK share the same PCB footprint?
No. Even though both use a 6-pin SOT-23 package, the pin assignments and functions differ due to the different interfaces. A board designed for one device cannot accept the other without layout changes and interface rework. Verify the pinout in each datasheet before considering any substitution.
Which device is better suited for a low-speed, bus-based sensor node?
The ADC121C021CIMK is generally better suited for low-speed, bus-based sensor nodes because its I2C interface allows multiple devices on a two-wire bus and its integrated alert function supports threshold monitoring. The ADC121S051CIMF is preferable when higher throughput and a SPI interface are required.