ADC122S051CIMMX - 12-Bit 500kSPS 2-Ch SAR ADC | Texas Instruments
MPN: ADC122S051CIMMX ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.65 | $4.65 |
| 10 | $4.18 | $41.80 |
| 100 | $3.72 | $372.00 |
| 500 | $3.35 | $1,675.00 |
| 1,000 | $2.99 | $2,990.00 |
ADC122S051CIMMX Overview
An SAR ADC is a type of data converter which uses a comparator sample and a switched binary-weighted internal representation to determine the digital sample. SAR converters belong to the family of successive approximation ADCs, which sit inside the broader hierarchy of data converters (ADC -> data converter -> mixed-signal IC -> semiconductor). SAR ADCs are valued in the broader system hierarchy for their deterministic latency, low power consumption, and ease of use in multiplexed multi-channel systems.
Key features include ±1 LSB INL/DNL (max), a SINAD of 71 dB (typical at 500 ksps, +5 V), power dissipation of 3.0 mW at +3 V and 10 mW at +5 V supply, and a -40 °C to +85 °C industrial operating temperature range. The serial output is straight binary and supports standard SPI, QSPI, MICROWIRE, and common DSP serial interfaces, enabling direct connection to microcontrollers and DSPs without glue logic.
The ADC122S051/ADC122S051Q family is built on a low-power CMOS process with an on-chip track-and-hold and a precision comparator. The converter uses an external clock (SCLK) to time the SAR conversion, providing deterministic throughput. The wide input range and modest supply current make this part well suited for portable instrumentation, sensor modules, and industrial control systems.
Typical applications include portable battery-powered data acquisition, multi-zone temperature and pressure sensing, industrial process monitors, optical module monitoring, and general-purpose multichannel front ends for embedded MCUs and DSPs. The dual-channel input MUX allows two sensors to share one ADC, lowering BOM cost and PCB area.
When designing with this device, place a 0.1uF decoupling capacitor close to the VA supply pin and route the analog inputs with a ground-referenced RC to eliminate ground bounce. Ensure that the SCLK line is clean and verify the SPI mode timing against the manufacturer datasheet. This part is now obsolete per distributor listings - consider pin-compatible replacements listed below for new designs.
This page synthesizes distributor availability, drop-in cross-reference data, and practical engineering guidance that goes beyond the manufacturer datasheet, including a parametric comparison vs pin-compatible TI/NSC and Microchip SAR ADC alternatives in the same VSSOP-8 footprint.
Drop-in alternatives for ADC122S051CIMMX — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ADC122S051CIMMX (same form factor and footprint) — differing in Package, Resolution, Interface, Architecture, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ADC122S051CIMM/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
ADC122S051QIMMX/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
ADC122S101CIMMX
✅ Drop-In📋 Reference alternative (not in catalog)
ADC122S021CIMMX
✅ Drop-In✓ In Stock
$2.35 / Unit
View Datasheet →ADC102S051CIMM
✅ Drop-In✓ In Stock
$1.52 / Unit
View Datasheet →ADC122S051CIMMX Maximum Ratings & Electrical Characteristics
| Manufacturer | Texas Instruments (originally National Semiconductor) |
| Part Number | ADC122S051CIMMX |
| Description | 2-Channel 200-500 ksps 12-Bit SAR ADC |
| Resolution | 12 bit |
| Number of Channels | 2 |
| Sample Rate | 200 ksps to 500 ksps |
| Architecture | SAR (Successive Approximation) |
| Supply Voltage | 2.7 V to 5.25 V (single supply) |
| Power Consumption | 3.0 mW at +3 V; 10 mW at +5 V |
| Input Type | Single-ended, 2:1 analog input MUX |
| Interface | SPI / QSPI / MICROWIRE / DSP-compatible serial |
| Output Format | Straight binary (SPI serial) |
| INL (max) | ±1 LSB |
| DNL (max) | ±1 LSB |
| SINAD (typ) | 71 dB at 500 ksps, +5 V supply |
| Operating Temperature | -40 °C to +85 °C |
| Package | 8-pin VSSOP (MSOP-8) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Lifecycle Status | Obsolete (per DigiKey listing) |
ADC122S051CIMMX Pin Configuration
| Pin 1 | VA — Analog supply voltage (+2.7V to +5.25V) |
| Pin 2 | IN1 — Analog input channel 1 |
| Pin 3 | IN0 — Analog input channel 0 |
| Pin 4 | GND — Ground |
| Pin 5 | SCLK — Serial clock input (SAR conversion timing) |
| Pin 6 | DOUT — Serial data output (SPI/QSPI/MICROWIRE compatible) |
| Pin 7 | DIN — Serial data input (for daisy-chain mode) |
| Pin 8 | CS — Chip select (active low) |
Typical Applications
ADC122S051CIMMX is suitable for 6 applications: Portable Battery-Powered Data Acquisition, Multi-Zone Temperature and Pressure Sensing, Industrial Process Monitoring, Optical Module Monitoring, General-Purpose MCU/DSP Sensor Front End, Consumer Audio and Video Signal Monitoring.
Portable Battery-Powered Data Acquisition
The ADC122S051CIMMX fits portable battery-powered data acquisition because of its 3.0 mW power dissipation at +3 V supply and 2.7 V minimum supply voltage, which is compatible directly with single-cell Li-ion discharge curves. Its 12-bit resolution and ±1 LSB INL provide sufficient accuracy for sensor front-ends in handheld multimeters, portable medical monitors, and field data loggers. The 500 ksps sample rate accommodates vibration or transient capture at low duty cycle. Placed between the sensor signal chain and an MCU's SPI bus, it adds deterministic SAR conversion latency and eliminates the need for an external reference, helping reduce PCB area in compact portable designs.
Recommended
Multi-Zone Temperature and Pressure Sensing
The ADC122S051CIMMX's 2-channel analog input MUX makes it ideal for multi-zone temperature and pressure sensing in HVAC, refrigeration, and industrial process monitoring. With 12-bit resolution and 500 ksps sample rate, the converter accurately digitizes thermocouple/thermistor bridges and bridge-type pressure sensors simultaneously, sharing one ADC across two sensors to lower BOM cost. Its -40 °C to +85 °C industrial temperature range covers outdoor and factory-floor deployments. Placed downstream of low-offset op-amp signal conditioning, it provides ±1 LSB linearity suitable for control-loop feedback that contributes to closed-loop stability in proportional-integral control systems.
Recommended
Industrial Process Monitoring
The ADC122S051CIMMX suits industrial process monitoring because of its wide 2.7-5.25 V supply tolerance, robust SPI interface, and 8-pin VSSOP industrial-grade packaging. Its deterministic SAR architecture avoids pipeline delay, simplifying closed-loop control where conversion latency matters. The 12-bit resolution (4096 codes) is sufficient for 4-20 mA loop reconstruction, level/position sensing, and motor current monitoring via shunt amplifiers. Placed between the signal conditioning stage and an industrial MCU/CPLD, it provides simultaneous sampling and helps code-loop rules in PLCs and SCADA I/O modules operating from 24 V industrial rails stepped down to 5 V or 3.3 V local rails.
Recommended
Optical Module Monitoring
The ADC122S051CIMMX is well suited for optical module monitoring in SFP/QSFP transceivers, where it digitizes laser bias current, temperature, and received signal strength indicator (RSSI) photodiode currents. Its small VSSOP-8 footprint fits the cramped interior of pluggable optics, and its 3.0 mW power consumption at +3.3 V keeps total module power budget within MSA specifications. The SPI interface is compatible with most optical module MCUs. The dual-channel input allows simultaneous laser driver monitoring and APD bias feedback, helping maintain optical eye-mask compliance and contributes to long-term reliability of the optical transponder in datacenter applications.
Recommended
General-Purpose MCU/DSP Sensor Front End
The ADC122S051CIMMX's SPI/QSPI/MICROWIRE/DSP-compatible serial interface makes it a natural general-purpose sensor digitizer for any 8/16/32-bit MCU or DSP that exposes a synchronous serial port. The 12-bit resolution covers most potentiometer, current-sensor, and audio-taper sensor applications without oversampling penalty. Its 500 ksps sample rate supports audio-bandwidth sampling to ~200 kHz. Placed between op-amp signal conditioning and an MCU's SPI peripheral, it provides deterministic conversion latency and helps code-loop rules in DSP-based motor control, audio processing, and general embedded sensor acquisition.
Recommended
Consumer Audio and Video Signal Monitoring
The ADC122S051CIMMX's 71 dB SINAD at 500 ksps and +5 V supply delivers >11.5 effective bits of dynamic range, suitable for consumer audio level metering, audio mixer monitoring, and video signal-level detection. Its dual input MUX allows monitoring of left/right channels or composite/S-video signals. The SPI interface connects directly to audio DSPs and video processors. Placed downstream of AC-coupled buffer amplifiers, it helps code-loop rules in automatic gain control (AGC) feedback paths and contributes to dynamic range preservation in consumer AV receivers and prosumer audio equipment operating at 3.3 V or 5 V supply rails.
Recommended
Recommended Products Summary
Engineering reference data for ADC122S051CIMMX — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADC122S051CIMM/NOPB | ADC122S051QIMMX/NOPB | ADC122S101CIMMX | ADC122S021CIMMX | ADC102S051CIMM |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 8-VSSOP | 8-VSSOP - same | 8-VSSOP - same | 8-VSSOP - same | 8-VSSOP - same | 8-VSSOP - same |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 10 bit |
| Sample Rate (max) | 500 ksps | 500 ksps | 500 ksps | 1000 ksps | 200 ksps | 500 ksps |
| Number of Channels | 2 | 2 | 2 | 2 | 2 | 2 |
| Supply Voltage | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V |
| Interface | SPI/QSPI/MICROWIRE/DSP | SPI/QSPI/MICROWIRE/DSP | SPI/QSPI/MICROWIRE/DSP | SPI/QSPI/MICROWIRE/DSP | SPI/QSPI/MICROWIRE/DSP | SPI/QSPI/MICROWIRE/DSP |
| Automotive Grade (AEC-Q100) | No | No | Yes | No | No | No |
| Lifecycle Status | Obsolete | Active | Active | Obsolete | Obsolete | Obsolete |
| Unit Price (qty 1, USD, as of 2026-10-12) | 4.65 | 4.25 | 5.40 | 5.10 | 3.95 | 3.45 |
Key Differentiators
- Active drop-in replacement available with same die (vs ADC122S051CIMM/NOPB)
- Automotive-grade option exists (vs ADC122S051QIMMX/NOPB)
- Family upward-compatible to higher sample rate (vs ADC122S101CIMMX)
- Family downward-compatible to lower speed/cost (vs ADC122S021CIMMX)
Design Notes
Place a 0.1uF X7R ceramic decoupling capacitor as close as possible to the VA pin (pin 1) and a 10uF bulk capacitor on the same supply trace. The ADC122S051 draws 3 mW typical at 3 V (1 mA quiescent) and 10 mW at 5 V (2 mA), so supply transient response matters during SAR switching events. A poorly decoupled supply can corrupt the LSBs of the conversion. Keep the VA trace short and away from switching converter inductors.
Route the analog inputs (IN0, IN1) with a ground-referenced RC low-pass filter (typically 10 ohm + 1 nF) close to the input pins to limit out-of-band noise and prevent charge injection kickback from the internal sample-and-hold from disturbing the upstream op-amp stage. Use a star-ground topology: tie the ADC GND pin directly to the analog ground plane, and avoid running digital return currents under the analog input traces.
The SCLK line is the most sensitive digital input because it sets the conversion timing. Keep SCLK routed away from the analog inputs and DOUT traces. If the SCLK source is more than 50 mm away, place a 33 ohm series termination resistor at the driver end to dampen reflections. Verify that SCLK frequency stays within the datasheet limit (typically 10 MHz for 500 ksps operation) and meets the t_CSD, t_SU, t_H timing parameters from the datasheet timing diagram.
Common pitfalls: (1) Failing to drive CS low before the first SCLK edge results in DOUT staying in high-Z and a missed conversion; (2) sampling rate selection: ensure the total SCLK cycles per conversion match the datasheet (16 SCLKs per 12-bit conversion) - too few cycles truncates data; (3) input voltage range: IN0/IN1 must remain between GND and VA - signals outside this range can permanently damage the input ESD structure; (4) read full 12 bits - do not stop at 8 bits or upper bits will be lost.
Compliance Information
RoHS/REACH compliant per TI product page and distributor listings. /NOPB variants (ADC122S051CIMM/NOPB) confirm Pb-free packaging. Not AEC-Q100 qualified in the standard grade - use ADC122S051QIMMX/NOPB for automotive. Originally released by National Semiconductor (NSC), now owned by Texas Instruments.
