MAX1238KEEE+T - 12-Bit, 12-Channel SAR ADC | Maxim Integrated
MPN: MAX1238KEEE+T ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.46 | $8.46 |
| 10 | $7.61 | $76.10 |
| 100 | $6.77 | $677.00 |
| 500 | $6.09 | $3,045.00 |
| 1,000 | $5.42 | $5,420.00 |
| 2,500 | $4.91 | $12,275.00 |
MAX1238KEEE+T Overview
A SAR ADC (Successive Approximation Register ADC) is a type of analog-to-digital converter that uses a binary search through an internal DAC to resolve an analog input into a digital code, one bit per conversion clock cycle. The SAR ADC family sits within the broader hierarchy of ADCs -> data converters -> mixed-signal ICs -> integrated circuits, and it is widely used when designers need a deterministic acquisition time, low latency, and moderate resolution (typically 8 to 18 bits) at sample rates up to a few MSPS.
Key features include 12-bit resolution with no missing codes, software-configurable unipolar/bipolar input ranges, an internal 2.5V reference (4.096V in the MAX1239 variant), single-ended or pseudo-differential channel configurations, and an I2C-compatible serial interface supporting both 400 kHz Fast Mode and 1.7 MHz High-Speed Mode. The 16-pin QSOP package measures approximately 3.9 mm wide, suiting compact PCB layouts where multiple analog sensors must be digitized close to the controller.
The architecture combines a capacitive DAC, a high-bandwidth track/hold front end, and an on-chip oscillator, eliminating the need for external precision components. An integrated sequencer can automatically scan all configured channels in one I2C transaction, reducing host firmware overhead in multi-sensor data acquisition loops.
Typical applications include battery monitoring in portable medical and industrial equipment, multi-cell battery pack voltage sensing in power tools and e-bikes, front-end digitizing for PLC analog input modules, temperature/pressure transducer arrays in process control, and general-purpose sensor multiplexing in 4 mA to 20 mA loop replacement designs.
When designing with this ADC, place the 0.1 µF supply bypass capacitor as close to pin 16 (VDD) and pin 1 (GND) as possible. Because the reference is internal, supply noise above 100 kHz couples directly into the conversion result; a ferrite bead or pi-filter on AVDD/REF is recommended when the part shares a rail with noisy digital or switching loads.
This page synthesizes distributor pricing from DigiKey and Mouser, pin-compatible same-family drop-in alternatives, and PCB-level design notes that are not duplicated in the manufacturer datasheet.
Drop-in alternatives for MAX1238KEEE+T — 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 MAX1238KEEE+T (same form factor and footprint) — differing in Resolution, Architecture, Package, Interface, Internal Reference Voltage.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1238EEE+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1238KEEE+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1239EEE+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1239KEEE+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1139MEEE+T
✅ Drop-In✓ In Stock
$3.9 / Unit
View Datasheet →MAX1139KEEE+
✅ Drop-In✓ In Stock
$4.45 / Unit
View Datasheet →MAX1238KEEE+T Maximum Ratings & Electrical Characteristics
| Resolution | 12 bit |
| Number of Analog Input Channels | 12 (single-ended) / 6 (pseudo-differential) |
| Architecture | SAR (Successive Approximation Register) |
| Input Type | Single-Ended, Pseudo-Differential |
| Supply Voltage - 3.3V Mode | 2.7 V to 3.6 V |
| Supply Voltage - 5V Mode | 4.5 V to 5.5 V |
| Supply Current at Max Throughput | 670 uA |
| Shutdown Supply Current | 1 uA |
| Internal Reference Voltage | 2.5 V |
| Digital Interface | I2C-compatible 2-wire serial (Fast Mode 400 kHz, High-Speed Mode 1.7 MHz) |
| Operating Temperature Range | -40 C to +85 C (extended) |
| Package | 16-QSOP (0.154 inch / 3.90 mm width) |
| Mounting Type | Surface Mount |
| Sampling Architecture | Internal Track/Hold with on-chip oscillator |
| RoHS Status | Compliant |
| Terminal Form | GULL WING |
| Temperature Grade | INDUSTRIAL |
MAX1238KEEE+T Pin Configuration
| Pin 1 | GND — Ground reference |
| Pin 2 | AIN0 — Analog input channel 0 |
| Pin 3 | AIN1 — Analog input channel 1 |
| Pin 4 | AIN2 — Analog input channel 2 |
| Pin 5 | AIN3 — Analog input channel 3 |
| Pin 6 | AIN4 — Analog input channel 4 |
| Pin 7 | AIN5 — Analog input channel 5 |
| Pin 8 | AIN6 — Analog input channel 6 |
| Pin 9 | AIN7 — Analog input channel 7 |
| Pin 10 | AIN8 — Analog input channel 8 |
| Pin 11 | AIN9 — Analog input channel 9 |
| Pin 12 | AIN10 — Analog input channel 10 |
| Pin 13 | AIN11 — Analog input channel 11 |
| Pin 14 | REF — Reference voltage I/O / external reference input |
| Pin 15 | SDA — I2C serial data |
| Pin 16 | VDD — Positive supply voltage (2.7V to 3.6V or 4.5V to 5.5V) |
Typical Applications
MAX1238KEEE+T is suitable for 6 applications: Multi-Cell Battery Pack Monitoring, Industrial PLC Analog Input Module, Portable Medical Sensor Hub, Process Control Transducer Array, HVAC Environmental Sensing Panel, Automotive Sensor Multiplexer Node.
Multi-Cell Battery Pack Monitoring
The MAX1238KEEE+T fits multi-cell battery pack monitoring because its 12 single-ended input channels can digitize up to 12 individual cell voltages in a single I2C transaction. With 12-bit resolution and the internal 2.5 V reference, each LSB represents 0.61 mV, providing accurate state-of-charge calculation in 1S-12S Li-ion or LiFePO4 packs where per-cell voltage must be measured to within tens of millivolts. The internal sequencer automatically scans all 12 channels, eliminating host-processor overhead and freeing the MCU for coulomb counting and protection logic. The 1 µA shutdown current is critical for sleep modes in portable power tools, e-bikes, and battery-backed industrial sensors where idle drain directly impacts runtime. Designers commonly pair this ADC with an external MOSFET-based front-end and a balancing circuit, then read all cell voltages over a single I2C bus to a battery management host.
Recommended
Industrial PLC Analog Input Module
The MAX1238KEEE+T fits industrial PLC analog input modules because it provides 12 isolated-grade analog input channels in a single 16-pin QSOP, dramatically reducing PCB area versus discrete op-amp-plus-ADC architectures. The 5 V supply compatibility (4.5 V to 5.5 V) matches the rail used in most PLC backplanes, and the I2C interface simplifies isolated I2C bus designs using digital isolators. Its 12-bit resolution with no missing codes and integrated track/hold deliver the linearity required for 4 mA to 20 mA loop replacement designs and process variable monitoring (pressure, level, flow). The I2C High-Speed Mode (1.7 MHz) lets the PLC scan all 12 channels in well under 1 ms, suiting sub-100 Hz control loops. When paired with an external surge protection front-end, the ADC delivers robust field-deployed performance for factory automation and SCADA systems.
Recommended
Portable Medical Sensor Hub
The MAX1238KEEE+T fits portable medical sensor hubs because its 12 input channels accommodate multiple biosensors (ECG, SpO2 red/IR, temperature, respiration, motion reference) on a single low-power ADC. The 670 µA active supply current at full throughput and 1 µA shutdown current allow duty-cycled acquisitions that extend battery life in wearable patient monitors and ambulatory diagnostic devices. The I2C-compatible interface with up to 8 selectable slave addresses enables multiple ADCs to coexist on the same bus, supporting expansion beyond 12 channels without firmware rearchitecture. The integrated 2.5 V reference eliminates the need for an external precision reference, saving critical board area in compact wearable form factors. Combined with the small QSOP package, this ADC is well-matched to multi-parameter bedside and home-care patient monitoring designs.
Recommended
Process Control Transducer Array
The MAX1238KEEE+T fits process control transducer arrays because it can digitize 12 individual sensor outputs from thermocouples, RTDs, strain gauges, and pressure transducers on a single I2C bus. The pseudo-differential input configuration enables rejection of common-mode ground noise in long cable runs typical of factory floor installations. The internal 2.5 V reference is ratiometric to bridge-type sensors, while the unipolar/bipolar input range lets the same ADC handle both 0-10V process signals and ±5V bipolar transducer outputs. Its extended -40 C to +85 C industrial temperature grade ensures operation in uncontrolled cabinet environments. When combined with RS-485 transceivers, this ADC provides the field-side digitizing front-end for distributed control systems (DCS) and remote I/O nodes.
Recommended
HVAC Environmental Sensing Panel
The MAX1238KEEE+T fits HVAC environmental sensing panels because its 12 inputs accommodate arrays of temperature, humidity, CO2, VOC, and airflow sensors distributed across a building automation node. The wide supply voltage range (2.7 V to 5.5 V) lets the same ADC operate from either 3.3 V or 5 V microcontroller rails without hardware changes. The 1.7 MHz I2C High-Speed Mode allows the controller to poll all 12 channels in under 1 ms, supporting real-time feedback loops in variable-air-volume (VAV) box controllers and economizer logic. The integrated sequencer minimizes firmware interrupt overhead, which is critical in resource-constrained 8-bit and Cortex-M0 host microcontrollers common in HVAC controllers. Combined with the QSOP package, this ADC is well-suited to compact panel-mount building automation designs.
Recommended
Automotive Sensor Multiplexer Node
The MAX1238KEEE+T fits automotive sensor multiplexer nodes because its 12 input channels can digitize multiple analog sensors (pedal position, throttle body, MAP, oil level, suspension travel) on a single ADC. Although not AEC-Q100 qualified itself, the MAX1238 is widely used in non-safety automotive body and chassis subsystems where industrial-grade -40 C to +85 C operation is sufficient. The wide 4.5 V to 5.5 V supply range tolerates 12 V battery transients when paired with external TVS protection, while the 670 µA active supply current keeps quiescent drain low in always-on body controllers. The I2C interface supports isolated or non-isolated communication with the central body control module via standard transceivers. This makes the part a cost-effective digitizing front-end for body electronics, comfort modules, and instrument cluster sub-boards.
Recommended
Recommended Products Summary
Engineering reference data for MAX1238KEEE+T — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1238EEE+ | MAX1238KEEE+ | MAX1239EEE+ | MAX1239KEEE+T | MAX1139MEEE+T | MAX1139KEEE+ |
|---|---|---|---|---|---|---|---|
| Brand | Analog Devices / Maxim Integrated | Analog Devices / Maxim Integrated | Analog Devices / Maxim Integrated | Analog Devices / Maxim Integrated | Analog Devices / Maxim Integrated | Analog Devices / Maxim Integrated | Analog Devices / Maxim Integrated |
| Package | 16-QSOP | 16-QSOP - same | 16-QSOP - same | 16-QSOP - same | 16-QSOP - same | 16-QSOP - same | 16-QSOP - same |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 10 bit | 10 bit |
| Number of Input Channels | 12 single-ended / 6 pseudo-differential | 12 / 6 | 12 / 6 | 12 / 6 | 12 / 6 | 12 / 6 | 12 / 6 |
| Supply Voltage Range | 2.7V-3.6V / 4.5V-5.5V | 2.7V-3.6V / 4.5V-5.5V | 2.7V-3.6V / 4.5V-5.5V | 2.7V-3.6V / 4.5V-5.5V | 2.7V-3.6V / 4.5V-5.5V | 2.7V-3.6V / 4.5V-5.5V | 2.7V-3.6V / 4.5V-5.5V |
| Digital Interface | I2C, 400 kHz / 1.7 MHz | I2C, 400 kHz / 1.7 MHz | I2C, 400 kHz / 1.7 MHz | I2C, 400 kHz / 1.7 MHz | I2C, 400 kHz / 1.7 MHz | I2C, 400 kHz / 1.7 MHz | I2C, 400 kHz / 1.7 MHz |
Key Differentiators
- 12-bit resolution with 12 single-ended channels in a 16-pin QSOP (vs MAX1139MEEE+T (10-bit family member))
- Higher 4.096 V internal reference option for 1 mV/LSB scaling (vs MAX1238KEEE+T (2.5 V reference))
- Integrated sequencer for automatic multi-channel scanning (vs Discrete ADC with external MUX)
Design Notes
Place a 0.1 µF X7R ceramic bypass capacitor as close as possible to pin 16 (VDD) and pin 1 (GND), with trace length under 2 mm. Add a 10 µF bulk capacitor on the same rail if the ADC is more than 25 mm from the system regulator. The internal 2.5 V reference draws transient current during conversion, so a poorly decoupled supply will inject reference noise directly into the conversion result.
Route the analog inputs (AIN0-AIN11) as parallel, matched-length traces on one side of the part, and keep the digital lines (SDA, SCL) on the opposite side. Place a digital ground guard ring around the ADC and tie it to the analog ground at a single point near the ADC ground pin. This prevents digital switching noise from coupling into the analog input traces via ground bounce.
When using the I2C High-Speed Mode (1.7 MHz), verify the bus rise-time spec with the actual pull-up resistor value and total bus capacitance. Excessive capacitance from long cable runs will violate the High-Speed Mode rise-time budget and force the host to fall back to 400 kHz Fast Mode. Adding a small series resistor (22-33 ohm) at the SDA and SCL pins can dampen ringing caused by bus stubs.
Do not leave the REF pin floating in external-reference mode; tie it through a low-impedance buffer to an external precision reference if higher accuracy is required. When using single-ended inputs, never exceed the input voltage range of 0 V to VREF, or the input ESD diodes will forward-bias and inject error currents into adjacent channels. Bipolar input ranges require the bipolar input configuration register to be set correctly in software.
Compliance Information
RoHS compliant per DigiKey product listing. Not AEC-Q100 qualified; not recommended for safety-critical automotive applications.
