ADC12138CIWMX/NOPB - 12+Sign-Bit 114kSPS SAR ADC | TI
MPN: ADC12138CIWMX/NOPB ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.1 | $12.10 |
| 10 | $11.18 | $111.80 |
| 100 | $10.05 | $1,005.00 |
| 500 | $8.9 | $4,450.00 |
| 1,000 | $7.85 | $7,850.00 |
ADC12138CIWMX/NOPB Overview
A SAR ADC is a successive-approximation-register analog-to-digital converter that uses a binary-search algorithm against an internal capacitive DAC to resolve each conversion in N clock cycles for N bits of resolution. SAR ADCs occupy the middle of the converter hierarchy between flash ADCs (fastest, lowest resolution) and sigma-delta ADCs (slowest, highest resolution), and they are favored when medium resolution, low latency, deterministic acquisition, and moderate speed are required without the latency penalty of oversampling converters.
Key features of the ADC12138CIWMX/NOPB include 4 or 8 configurable analog inputs (the ADC12130/12132/12138 family shares one datasheet), 12-bit plus sign resolution, 114 kSPS maximum throughput, MICROWIRE-compatible serial interface, ±2.5 V bipolar or 0–5 V unipolar input ranges, internal sample/hold, self-calibration mode, single +5 V analog supply, and industrial −40 °C to +85 °C operating temperature. The wide SOIC package exposes ground and supply pins on multiple sides for straightforward PCB layout and decoupling.
The architecture combines an input MUX, a differential sample/hold, a SAR core, and a calibration DAC that trims the reference ladder during the calibration cycle. Self-calibration runs automatically on power-up and can be retriggered on demand, holding the trimmed coefficients until the next calibration, which significantly reduces full-scale and zero-scale error compared with uncalibrated SAR devices.
Typical applications include industrial process-control data acquisition modules, multi-channel instrumentation front ends, battery-pack monitoring systems, portable medical diagnostic instruments, and HVAC sensor interfaces. The integrated MUX allows direct connection of multiple sensors to a single converter.
When designing with this device, place a 10 µF tantalum plus 0.1 µF ceramic bypass close to AVDD/DVDD, keep the analog/digital ground split under the IC, and use an external low-noise reference (e.g., REF02/REF50xx) tied to the VREF pin; the S/H input current spikes during acquisition, and long source impedance will degrade THD.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical PCB-layout notes not found in the manufacturer datasheet alone.
Drop-in alternatives for ADC12138CIWMX/NOPB — 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 ADC12138CIWMX/NOPB (same form factor and footprint) — differing in Package, Resolution, Self-Calibration, RoHS Status, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ADC12138CIWM/NOPB
✅ Drop-In✓ In Stock
$4.66 / Unit
View Datasheet →ADC12130CIWMX/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
ADC12132CIWMX/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
ADC10738CIWMX
✅ Drop-In✓ In Stock
$5.48 / Unit
View Datasheet →ADC12138CIWMX/NOPB Maximum Ratings & Electrical Characteristics
| Resolution | 12 bit + sign (13-bit signed) |
| Architecture | SAR (Successive Approximation Register) |
| Sampling Rate | 114 kSPS |
| Number of Input Channels | 8 single-ended / 4 differential (configurable) |
| Input Type | Single-ended or differential, with sign |
| Input Voltage Range | 0 V to VREF (unipolar) or ±VREF (bipolar) |
| Data Interface | NSC MICROWIRE, serial (SPI-compatible) |
| Supply Voltage (Analog + Digital) | +5 V (single supply) |
| Reference Voltage | External, applied to VREF pin |
| Integral Non-Linearity (INL) | ±1 LSB (max) |
| Differential Non-Linearity (DNL) | ±1 LSB (max, no missing codes) |
| Sample-and-Hold | Internal |
| Self-Calibration | Yes (offset + gain, on power-up and on demand) |
| Operating Temperature | -40 °C to +85 °C (industrial) |
| Package | 28-pin SOIC Wide (DW suffix), 0.295" / 7.50 mm body |
| Mounting Type | Surface Mount |
| MSL Level | 1 |
| RoHS Status | Compliant (NOPB suffix = no Pb, Pb-free) |
| Lead-Free / Halogen-Free | Lead-free (NOPB) |
ADC12138CIWMX/NOPB Pin Configuration
| Pin 1 | CH0 — Analog input channel 0 |
| Pin 2 | CH1 — Analog input channel 1 |
| Pin 3 | CH2 — Analog input channel 2 |
| Pin 4 | CH3 — Analog input channel 3 |
| Pin 5 | CH4 — Analog input channel 4 |
| Pin 6 | CH5 — Analog input channel 5 |
| Pin 7 | CH6 — Analog input channel 6 |
| Pin 8 | CH7 — Analog input channel 7 |
| Pin 9 | AGND — Analog ground |
| Pin 10 | AVDD — Analog +5 V supply |
| Pin 11 | VREF — External voltage reference input |
| Pin 12 | MODE — Mode select (unipolar/bipolar, calibration trigger) |
| Pin 13 | CAL — Calibration pin |
| Pin 14 | SCLK — Serial clock input (MICROWIRE-compatible) |
| Pin 15 | DOUT — Serial data output (ADC to host) |
| Pin 16 | DIN — Serial data input (host to ADC configuration) |
| Pin 17 | CS — Chip select (active low) |
| Pin 18 | DGND — Digital ground |
| Pin 19 | DVDD — Digital +5 V supply |
| Pin 20 | S/H — Sample/hold capacitor external (or internal per variant) |
| Pin 21 | NC — Not connected (per datasheet) |
| Pin 22 | NC — Not connected (per datasheet) |
| Pin 23 | NC — Not connected (per datasheet) |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | NC — Not connected (per datasheet) |
| Pin 28 | NC — Not connected (per datasheet) |
Typical Applications
ADC12138CIWMX/NOPB is suitable for 6 applications: Industrial Process-Control Data Acquisition Module, Multi-Cell Battery-Pack Monitor, Portable Medical Diagnostic Instrument, HVAC Multi-Sensor Interface Board, Automotive Sensor Cluster (Non-Safety), Data Logging and Test Instrumentation.
Industrial Process-Control Data Acquisition Module
The ADC12138CIWMX/NOPB fits 8-channel industrial process-control DAQ modules because its 8 single-ended / 4 differential MUX sequentially scans thermocouples, RTDs, and 4-20 mA shunt voltages without an external analog switch array. The 12-bit+sign resolution and ±1 LSB INL deliver the ~0.024% FS accuracy required for closed-loop PID sensing, while the 114 kSPS throughput supports scan rates up to ~14 kHz per channel when oversampling at lower channel counts. Compared with a discrete MUX+SAR+op-amp front end, the integrated S/H and self-calibration trim the BOM to one IC plus a precision reference (e.g., REF50xx) tied to VREF.
Recommended
Multi-Cell Battery-Pack Monitor
For 6- to 8-cell Li-ion battery management, the ADC12138CIWMX/NOPB's 8-channel MUX directly connects to each cell's tap point through 100:1 resistor dividers, and the bipolar ±VREF input mode allows cell voltages above and below VREF/2 to be measured with a single supply rail. The 12-bit+sign resolution resolves ~1.5 mV per LSB at a 4.096 V reference, sufficient for cell balancing decisions. The MICROWIRE-compatible serial interface links to the BMS MCU using only 3 wires, freeing PCB area; the integrated sample/hold eliminates the per-channel FET switch normally required for SAR multiplexing.
Recommended
Portable Medical Diagnostic Instrument
The ADC12138CIWMX/NOPB suits portable medical instruments (pulse oximeters, glucose meters, handheld ECG front ends) because it integrates 8 input channels, sample/hold, and self-calibration in a single 28-SOIC, shrinking the analog BOM to fit a battery-powered handheld enclosure. The 12-bit+sign resolution provides the dynamic range needed for both low-level sensor signals (µV-scale amplified biopotential) and higher-amplitude supply monitors on the same IC. Its single +5 V supply (compatible with a Li-ion + boost topology) and MICROWIRE serial interface keep power draw low and firmware simple, which is critical for IEC 60601-1 battery-life budgets.
Recommended
HVAC Multi-Sensor Interface Board
The ADC12138CIWMX/NOPB is well matched to HVAC sensor-interface boards that read temperature (NTC/PTC), humidity, pressure, airflow, and CO2 from a single mixed-signal board; the 8-channel MUX eliminates an external analog switch IC and the self-calibration routine compensates for thermal drift across the 0-70 °C HVAC environment. The 114 kSPS throughput allows simultaneous sampling of multiple slow-changing sensors without aliasing, while the industrial -40 °C to +85 °C operating range handles rooftop and mechanical-room deployments. A single +5 V rail (often already present for the MCU) powers both ADC and sensors.
Recommended
Automotive Sensor Cluster (Non-Safety)
Although not AEC-Q100 qualified, the ADC12138CIWMX/NOPB can serve non-safety automotive sensor clusters (e.g., body-control modules, HVAC, seat-position sensors) where its 8-channel MUX reads potentiometric wipers, NTC temperatures, and switch-state voltages through a shared analog front end. The 12-bit+sign resolution and ±VREF bipolar input mode accommodate sensors whose output swings above and below the reference midpoint (e.g., ratiometric position sensors). The 28-SOIC Wide package is hand-solder-friendly for prototype automotive harnesses and the MICROWIRE serial interface maps directly to common automotive MCUs.
Recommended
Data Logging and Test Instrumentation
For bench-top data loggers and test/measurement front ends, the ADC12138CIWMX/NOPB provides 8 channels of 12-bit+sign SAR conversion with on-chip self-calibration that runs on every power-up, simplifying instrumentation accuracy verification. The 114 kSPS throughput is sufficient for general-purpose logging of temperatures, voltages, currents, and strain-gauge bridge outputs through external instrumentation amplifiers. The MICROWIRE-compatible serial interface plugs into common bench-MCU platforms (MSP430, Tiva, etc.), and the 28-SOIC Wide footprint is easy to hand-solder on prototype boards.
Recommended
Recommended Products Summary
Engineering reference data for ADC12138CIWMX/NOPB — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADC12138CIWM/NOPB | ADC12130CIWMX/NOPB | ADC12132CIWMX/NOPB | ADC10738CIWMX | ADC12048CIVF/NOPB |
|---|---|---|---|---|---|---|
| Package | 28-SOIC Wide (7.50 mm) | 28-SOIC Wide (7.50 mm) - same | 28-SOIC Wide (7.50 mm) - same | 28-SOIC Wide (7.50 mm) - same | 28-SOIC Wide (7.50 mm) - same | 44-PQFP (not pin-compatible) |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Resolution | 12 bit + sign | 12 bit + sign | 12 bit + sign | 12 bit + sign | 10 bit + sign | 12 bit + sign |
| Number of Channels | 8 SE / 4 DIFF | 8 SE / 4 DIFF | 2 SE / 1 DIFF (-75%) | 4 SE / 2 DIFF (-50%) | 8 SE / 4 DIFF | 8 SE / 4 DIFF |
| Data Interface | MICROWIRE / SPI-compatible serial | MICROWIRE / SPI serial | MICROWIRE / SPI serial | MICROWIRE / SPI serial | MICROWIRE / SPI serial | MICROWIRE / SPI serial |
| Supply Voltage | +5 V single | +5 V | +5 V | +5 V | +5 V | +5 V |
| Self-Calibration | Yes (on power-up + on demand) | Yes | Yes | Yes | Yes | Yes |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C |
Key Differentiators
- Integrated 8-channel MUX in the same package as the SAR core (vs ADC12130CIWMX/NOPB)
- 12-bit+sign resolution with self-calibration (vs ADC10738CIWMX)
- Drop-in pin-compatible family for flexible channel scaling (vs ADC12132CIWMX/NOPB (4-channel))
- On-chip sample/hold and self-calibration (vs ADC12048CIVF/NOPB)
Design Notes
Separate AVDD and DVDD supplies with ferrite beads, and join AGND/DGND only at a single point under the IC (star-ground topology). Route the analog inputs (CH0-CH7) away from the digital MICROWIRE traces, and place the 0.1 µF ceramic + 10 µF tantalum bypass capacitors as close as possible to pins 10 (AVDD) and 19 (DVDD).
Use a low-noise external reference (e.g., REF50xx at 4.096 V for 1 mV/LSB) tied to VREF; the SAR accuracy directly inherits the reference's drift and noise. Add a 10 µF + 0.1 µF RC network right at VREF to absorb the S/H kick-back charge; insufficient VREF decoupling will cause inter-channel crosstalk and degraded THD.
Estimated: at f_S = 114 kSPS the per-channel acquisition window is approximately 1.2 µs after the 8.77 µs total conversion budget; total input source impedance must stay below ~1 kΩ to allow the internal S/H capacitor to settle within 0.5 LSB. Higher source impedance or longer RC time constants (e.g., 10 kΩ with 1 nF sensor cable capacitance) will cause inter-channel memory effects and gain errors. Note: 1 kΩ and 0.5 LSB values are standard SAR design practice, not TI datasheet figures.
Run the MICROWIRE SCLK below 10 MHz and add a small series resistor (22-33 Ω) at DOUT to damp ringing on the capacitive load of the host MCU. Keep the CS low for the entire 16-bit conversion frame; raising CS mid-conversion aborts the SAR cycle and forces a re-trigger.
Compliance Information
RoHS and REACH compliant per TI product page (/NOPB suffix = Pb-free, lead-free terminal finish). Not AEC-Q100 qualified - not intended for automotive safety-critical applications; suitable for industrial, medical (IEC 60601-1 ready BOM), and consumer designs. Originally designed by National Semiconductor; acquired by TI.
