ADC12138CIMSA - 12-Bit+Sign SAR ADC, 8-Ch MUX, Serial I/O | TI
MPN: ADC12138CIMSA ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.95 | $8.95 |
| 10 | $8.05 | $80.50 |
| 100 | $7.15 | $715.00 |
| 500 | $6.4 | $3,200.00 |
| 1,000 | $5.72 | $5,720.00 |
ADC12138CIMSA Overview
A SAR ADC (Successive Approximation Register Analog-to-Digital Converter) is a type of data converter that performs a binary search through an internal DAC to digitize an analog input one bit at a time per clock cycle. Within the broader taxonomy, the ADC12138 belongs to the data-converter -> ADC -> SAR-ADC -> precision ADC hierarchy of mixed-signal integrated circuits, making it suitable for medium-speed, multi-channel measurements where deterministic latency and high DC accuracy are required.
Key features include on-chip self-calibration that corrects offset and linearity errors at power-up or on demand, a serial interface (SPI/QSPI/MICROWIRE-compatible) that minimizes pin count on the 28-SSOP footprint, an 8-channel analog input multiplexer for sensor-scanning applications, low power consumption (typically < 5 mW at 5 V), and an industrial operating temperature range of -40 °C to +85 °C.
The architecture combines a capacitive charge-redistribution DAC with a successive-approximation register and an input sample-and-hold amplifier. The self-calibration sequence stores correction coefficients on-chip so that subsequent conversions achieve specified linearity without user trimming. The serial I/O block supports daisy-chaining so multiple devices can share one SPI bus, useful for multi-MUX scanning in industrial front-ends.
Typical applications include industrial process-control front ends, multi-sensor data acquisition boards, weigh scales, battery-monitoring systems, and portable instrumentation. The combination of an 8-channel input MUX, self-calibration, and serial output makes it attractive when a single host microcontroller must scan many analog sensors while keeping the BOM small.
When designing with this ADC, pay attention to the analog input bandwidth and acquisition-time requirements versus the source impedance of the MUX channels. Place a 0.1 µF decoupling capacitor close to AVDD and DVDD, keep analog and digital grounds separated, and route reference and analog traces away from switching signals to preserve linearity.
This page synthesizes distributor stock levels, drop-in same-package alternatives, comparison data, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ADC12138CIMSA — 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 ADC12138CIMSA (same form factor and footprint) — differing in Analog Supply Voltage, Digital Supply Voltage, Number of Input Channels, Operating Temperature, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ADC12138CIMSA/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
ADC12138CIMSAX/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
ADC12132CIMSA
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →ADC12130CIMSA
✅ Drop-In📋 Reference alternative (not in catalog)
ADC12138CIWM
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.8 / Unit
View Datasheet →ADC12138CIN
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ADC12138CIMSA Maximum Ratings & Electrical Characteristics
| Resolution | 12-bit plus sign (13-bit dynamic range) |
| Number of Input Channels | 8 single-ended / 4 differential (plus COM) |
| Conversion Architecture | SAR (Successive Approximation) |
| Input MUX | 8-channel analog multiplexer |
| Sample/Hold | On-chip input sample-and-hold |
| Interface | Serial (SPI/QSPI/MICROWIRE-compatible) |
| Self-Calibration | On-chip auto-calibration (offset + linearity) |
| Analog Supply Voltage | 3.0 V to 5.5 V (single supply) |
| Digital Supply Voltage | Same as AVDD |
| Operating Temperature | -40 °C to +85 °C (industrial) |
| Package | 28-pin SSOP (MSA) |
| Mounting Type | Surface Mount |
| RoHS Status | Non-RoHS (original); NOPB suffix is RoHS-compliant |
| Daisy-Chain Support | Yes (multi-device serial bus) |
ADC12138CIMSA Pin Configuration
| Pin 1 | DGND — Digital ground |
| Pin 2 | AVDD — Analog supply voltage |
| Pin 3 | DVDD — Digital supply voltage |
| Pin 4 | VREF — Voltage reference input |
| Pin 5 | COM — Common reference for differential inputs |
| Pin 6 | AIN0 — Analog input channel 0 |
| Pin 7 | AIN1 — Analog input channel 1 |
| Pin 8 | AIN2 — Analog input channel 2 |
| Pin 9 | AIN3 — Analog input channel 3 |
| Pin 10 | AIN4 — Analog input channel 4 |
| Pin 11 | AIN5 — Analog input channel 5 |
| Pin 12 | AIN6 — Analog input channel 6 |
| Pin 13 | AIN7 — Analog input channel 7 |
| Pin 14 | NC — Not connected (per datasheet) |
| Pin 15 | SCLK — Serial clock input |
| Pin 16 | DOUT — Serial data output |
| Pin 17 | DIN — Serial data input |
| Pin 18 | CS — Chip select (active low) |
| Pin 19 | CONVST — Conversion start input |
| Pin 20 | CAL — Calibration control input |
| Pin 21 | MODE — Mode select input |
| Pin 22 | AGND — Analog ground |
| Pin 23 | AGND — Analog ground |
| Pin 24 | AGND — Analog ground |
| Pin 25 | AGND — Analog ground |
| Pin 26 | AGND — Analog ground |
| Pin 27 | AGND — Analog ground |
| Pin 28 | AGND — Analog ground |
Typical Applications
ADC12138CIMSA is suitable for 6 applications: Industrial Process-Control Front End, Multi-Sensor Data Acquisition Board, Weigh Scales and Load-Cell Instrumentation, Battery Monitoring and Management, Portable Instrumentation and Field Meters, Automotive Sensor Signal Conditioning.
Industrial Process-Control Front End
The ADC12138CIMSA fits industrial process-control front ends because its 8-channel analog multiplexer scans up to eight sensor inputs (temperature, pressure, flow) from a single host, reducing BOM and wiring cost. The 12-bit-plus-sign resolution captures small bipolar sensor signals around 0 V with sufficient dynamic range for 4-20 mA / 0-10 V loops after scaling, while on-chip self-calibration corrects offset and linearity drift over the -40 °C to +85 °C industrial temperature range. Compared with discrete MUX + ADC solutions, the integrated approach cuts PCB real estate and eliminates MUX-channel-to-channel crosstalk calibration.
Recommended
Multi-Sensor Data Acquisition Board
For multi-sensor data-acquisition boards in test equipment and embedded instrumentation, the ADC12138CIMSA provides 8 single-ended or 4 differential inputs on one serial bus, allowing a single microcontroller to scan many analog channels without a large parallel bus. The on-chip sample-and-hold removes external components, and the SAR architecture gives deterministic latency suitable for synchronous sampling. The serial I/O supports SPI/QSPI/MICROWIRE hosts and daisy-chaining of multiple ADCs, useful when more than 8 channels are required in distributed acquisition systems.
Recommended
Weigh Scales and Load-Cell Instrumentation
The ADC12138CIMSA is well suited to weigh scales and load-cell instrumentation because the 12-bit-plus-sign output provides 13-bit effective dynamic range needed to resolve small differential signals from strain-gauge bridges. The 8-channel MUX allows multi-load-cell scanning in platform scales. On-chip offset and linearity self-calibration removes the need for manual trim pots that would otherwise be required to null bridge offset - a major cost and labour saving in volume production. The serial interface simplifies isolation in line-voltage-powered scale designs.
Recommended
Battery Monitoring and Management
In battery-monitoring systems (BMS) for industrial UPS or e-mobility battery stacks, the ADC12138CIMSA's 8-channel input MUX can monitor up to 8 cell voltages sequentially through a multiplexer ladder, while the SAR architecture provides deterministic conversion time per channel - critical for synchronised cell balancing. The 3.0-5.5 V supply range aligns with 3.3 V and 5 V battery-rail domains, and self-calibration compensates for temperature drift across the operating range. For new designs with higher cell counts, the modern ADC128S102 family is recommended.
Recommended
Portable Instrumentation and Field Meters
Portable handheld instruments and field meters benefit from the ADC12138CIMSA's small 28-SSOP footprint, low power consumption (under 5 mW typical at 5 V), and on-chip calibration that maintains performance without user interaction. The serial interface minimises host pin count - critical for compact microcontroller-based meter designs with limited GPIO. The -40 °C to +85 °C operating range supports outdoor and industrial field use where temperature extremes are common, and the 8-channel MUX lets one meter read multiple sensor types (voltage, current, temperature) on a single chip.
Recommended
Automotive Sensor Signal Conditioning
Although the ADC12138CIMSA itself is not AEC-Q100 qualified, its 8-channel architecture and serial interface make it a candidate for non-safety automotive applications such as body-comfort modules, HVAC sensor interfaces, and battery management peripherals where automotive-grade certification is not mandated. The wide supply range accepts 12 V automotive rails after regulation, while on-chip calibration compensates for the large temperature swings encountered under-dash. For new AEC-Q100 designs, TI's automotive SAR ADC portfolio should be evaluated instead.
Recommended
Recommended Products Summary
Engineering reference data for ADC12138CIMSA — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADC12138CIMSA/NOPB | ADC12138CIMSAX/NOPB | ADC12132CIMSA | ADC12130CIMSA |
|---|---|---|---|---|---|
| Package | 28-SSOP (MSA) | 28-SSOP (MSA) - same | 28-SSOP (MSA) - same | 28-SSOP (MSA) - same | 28-SSOP (MSA) - same |
| Brand | Texas Instruments | Texas Instruments - same | Texas Instruments - same | Texas Instruments - same | Texas Instruments - same |
| Resolution | 12-bit + sign | 12-bit + sign - same | 12-bit + sign - same | 12-bit + sign - same | 12-bit + sign - same |
| Input Channels | 8 single-ended / 4 differential | 8 / 4 - same | 8 / 4 - same | 2 / 1 (75% fewer) | 1 / 0 (87.5% fewer) |
| Self-Calibration | On-chip (offset + linearity) | On-chip - same | On-chip - same | On-chip - same | On-chip - same |
| RoHS Compliance | Non-RoHS (original) | RoHS-compliant (Pb-free) | RoHS-compliant (Pb-free) | Non-RoHS (original) | Non-RoHS (original) |
| Interface | Serial SPI/QSPI/MICROWIRE | Serial - same | Serial - same | Serial - same | Serial - same |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C - same | -40 °C to +85 °C - same | -40 °C to +85 °C - same | -40 °C to +85 °C - same |
Key Differentiators
- Highest channel count in 28-SSOP TI SAR ADC family (vs ADC12132CIMSA)
- On-chip self-calibration eliminates manual trim (vs Generic 12-bit SAR ADCs without calibration)
- Drop-in RoHS-compliant version available (vs ADC12138CIMSA (non-RoHS))
- True bipolar measurement via 12-bit + sign output (vs Single-supply 12-bit ADCs without sign bit)
Design Notes
Place a 0.1 µF ceramic decoupling capacitor as close as possible to the AVDD pin (pin 2) and another to the DVDD pin (pin 3); add a 10 µF bulk capacitor on the supply rail to suppress switching noise from the digital supply. The analog and digital supplies can be tied together for most applications, but for noise-sensitive measurements TI recommends separating them with a ferrite bead or small resistor (10-100 Ω). Power-up ramp should allow at least 1 ms for supplies to settle before initiating a calibration sequence.
Use a star-ground topology with separate analog and digital ground planes joined at a single point near the ADC ground pins. Route analog input traces (AIN0-AIN7, COM, VREF) away from digital lines (SCLK, DOUT, DIN, CS) to minimise digital coupling into the analog front end. Keep VREF traces short and surrounded by ground pour to reduce noise pickup. Use guard rings around analog input pins if the PCB will be exposed to humidity or contamination.
Source impedance at the analog input pins should be kept below 1 kΩ to avoid conversion errors caused by incomplete settling of the input sample-and-hold capacitor. Add an external input RC filter (typically 100 Ω + 1 nF) at each MUX channel for EMI suppression in industrial environments. The VREF pin should be driven from a low-impedance, low-noise reference such as the TI REF02 or REF30xx; noise on VREF directly translates into conversion noise on the output.
Do not skip the on-chip self-calibration sequence - skipping it will leave offset and linearity errors uncorrected, degrading effective resolution. Issue a calibration cycle after power-up, after a VREF change, or after significant temperature shifts (>10 °C). Do not operate the ADC with input voltages outside 0 V to VREF (single-ended) or ±VREF (differential); signals beyond this range saturate the input sample-and-hold and may damage the part via ESD. Always deassert CS during the conversion window to avoid spurious serial activity.
Estimated: at 5 V operation with continuous conversion enabled, the ADC12138CIMSA typically dissipates < 5 mW. The 28-SSOP package has theta-JA around 95 °C/W, so junction temperature rise is < 0.5 °C above ambient - thermal management is not a concern for this part in normal operation. However, in enclosed industrial enclosures operating near 85 °C ambient, ensure adequate airflow or heatsinking of nearby power components to avoid localised heating of the ADC.
Compliance Information
Original ADC12138CIMSA contains lead-bearing finish and is NOT RoHS-compliant. The /NOPB suffix version is lead-free RoHS-compliant. Device is not AEC-Q100 qualified. For automotive applications, modern AEC-Q100 SAR ADCs from TI should be selected.
