MAX1238LEEE+T - 12-Ch 12-Bit 94.4ksps I2C SAR ADC | Analog Devices
MPN: MAX1238LEEE+T ✓ Hoạt độngMAX1238LEEE+T Tóm tắt
A SAR ADC (Successive Approximation Register Analog-to-Digital Converter) is a type of analog-to-digital converter that uses a binary-search feedback loop with an internal DAC to digitize an analog input, producing one conversion per N clock cycles for N bits of resolution. SAR ADCs sit in the hierarchy: ADC -> data converter -> mixed-signal IC -> semiconductor. They are favored over delta-sigma and pipeline ADCs when low latency, deterministic sample timing, and a small footprint are needed, which is why they dominate multi-channel sensor-acquisition and embedded instrumentation front-ends.
Key specifications include 12-bit resolution, ±1 LSB INL/DNL (typ.), an internal 4.096 V reference with 50 ppm/°C tempco, an input range of 0 V to VREF (unipolar) or ±VREF (bipolar software-configurable), a software-configurable unipolar/bipolar mode with 4 single-ended or 12 differential inputs, an I2C-compatible 2-wire serial interface running at up to 400 kHz in standard mode, an integrated temperature sensor with ±2 °C accuracy, and operation over the extended industrial temperature range of -40 °C to +85 °C.
The architecture combines an internal charge-redistribution DAC, sample-and-hold, configurable input multiplexer, and internal clock, so external components are limited to bypass capacitors and pull-ups on the I2C bus. Power-down sequencing through software reduces quiescent current to sub-microamp levels between conversions, making it suitable for battery-powered sensor polling.
Typical applications include portable data-acquisition loggers, industrial process-control sensor multiplexing, thermocouple and RTD temperature measurement, medical instrumentation front-ends, battery-powered handheld test equipment, and remote HVAC monitoring. The integrated temperature sensor is useful for cold-junction compensation in thermocouple chains. Designers should keep analog and digital grounds joined at a single point near the IC and place 1 µF + 0.1 µF decoupling caps close to AVDD/DVDD to preserve 12-bit noise performance across heavy digital switching. Pricing is current as of 2026-10-14 and reflects typical distributor inventory.
Bộ thay thế dễ dàng lắp đặt cho MAX1238LEEE+T — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với MAX1238LEEE+T (cùng hình factor và footprint) — khác nhau ở Resolution, Interface, Internal Reference, Operating Temperature, Supply Voltage.
MAX1238EEE+T
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX1238EEE+
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX1139MEEE+T
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MAX1139KEEE+
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MAX1239LEEE+
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MAX1039LEEE
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX1238LEEE+T Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 12 bit |
| Architecture | SAR (Successive Approximation) |
| Analog Input Channels | 6 or 12 single-ended / 12 differential (software-configurable) |
| Input Type | Differential, Single-Ended |
| Sampling Rate (max) | 94.4 ksps |
| Analog Supply Voltage (AVDD) | 4.5 V to 5.5 V (MAX1236/MAX1238 family) |
| Supply Current (max sample rate) | 670 µA at 94.4 ksps |
| Điện áp tắt | 0.5 µA |
| Integral Nonlinearity (INL) | ±1 LSB (typical) |
| Differential Nonlinearity (DNL) | ±1 LSB (typical) |
| Internal Reference | 4.096 V |
| Reference Tempco | 50 ppm/°C |
| Serial Interface | I2C-compatible 2-wire, up to 400 kHz |
| Khoảng nhiệt độ hoạt động | -40 °C to +85 °C |
| Internal Temperature Sensor Accuracy | ±2 °C |
| Hộp | 16-pin QSOP (SSOP equivalent, 0.154" / 3.90 mm body width) |
| Kiểu lắp đặt | Surface Mount |
| Trạng thái RoHS | Compliant |
Cấu hình chân MAX1238LEEE+T
| Chân 1 | AIN0 / AIN0+ — Analog input channel 0 (single-ended) or differential positive input 0 |
| Chân 2 | AIN1 / AIN0- — Analog input channel 1 (single-ended) or differential negative input 0 |
| Chân 3 | AIN2 / AIN1+ — Analog input channel 2 (single-ended) or differential positive input 1 |
| Chân 4 | AIN3 / AIN1- — Analog input channel 3 (single-ended) or differential negative input 1 |
| Chân 5 | AIN4 / AIN2+ — Analog input channel 4 (single-ended) or differential positive input 2 |
| Chân 6 | AIN5 / AIN2- — Analog input channel 5 (single-ended) or differential negative input 2 |
| Chân 7 | AIN6 / AIN3+ — Analog input channel 6 (single-ended) or differential positive input 3 |
| Chân 8 | AIN7 / AIN3- — Analog input channel 7 (single-ended) or differential negative input 3 |
| Chân 9 | AVDD — Analog supply voltage, 4.5 V to 5.5 V, decouple with 0.1 µF + 10 µF ceramic as close as possible |
| Chân 10 | GND — Ground reference for both analog and digital supplies - use single-point ground |
| Chân 11 | REF — Voltage reference input/output - internal 4.096 V reference; can be overdriven by external reference |
| Chân 12 | DVDD — Digital supply voltage, 2.7 V to 5.5 V, decouple with 0.1 µF + 10 µF ceramic |
| Chân 13 | SDA — I2C-compatible serial data line, open-drain; requires external pull-up resistor |
| Chân 14 | SCL — I2C-compatible serial clock line, open-drain input; requires external pull-up resistor |
| Chân 15 | AIN10 / AD1 — Analog input channel 10 (single-ended) or I2C slave-address bit 1 |
| Chân 16 | AIN11 / AD0 — Analog input channel 11 (single-ended) or I2C slave-address bit 0 |
Ứng dụng tiêu biểu
MAX1238LEEE+T phù hợp cho 6 Áp dụngs: Battery-Powered Multi-Channel Data Logger, Industrial Process Control Sensor Multiplexing, Thermocouple and RTD Temperature Measurement, Portable Handheld Test Instruments, Medical Instrumentation Front-Ends, HVAC and Environmental Sensor Nodes.
Battery-Powered Multi-Channel Data Logger
The MAX1238LEEE+T's 670 µA at 94.4 ksps and 0.5 µA shutdown current make it a strong fit for battery-powered multi-channel data loggers that wake, sample all 12 channels, and return to sleep. With 12-bit resolution across 0 V to 4.096 V the 1 LSB size is 1 mV, sufficient for slow thermocouple and 4-20 mA shunt signals in industrial logging. Pairing the on-chip 50 ppm/°C reference eliminates external precision references; only bypass caps are required for full 12-bit performance. Estimated: at a 1 Hz aggregate sampling rate with shutdown between conversions, average supply current drops to roughly 5 µA, so a 1000 mAh Li-coin cell can run for >3 years.
Được đề xuất
Industrial Process Control Sensor Multiplexing
The MAX1238LEEE+T's 6/12-channel software-configurable mux aligns directly with industrial PLC analog input modules that aggregate multiple 4-20 mA or 0-10 V process signals. The internal 4.096 V reference is convenient when scaling 4-20 mA shunts (250 Ω gives 1-5 V), while ±1 LSB INL/DNL satisfies 0.1%-of-full-scale accuracy needed for level and pressure transmitters. Integrated temperature sensing can compensate cold junctions of remote thermocouples wired to the multiplexer inputs. The -40 °C to +85 °C operating range covers IEC 60068 industrial cabinet profiles; for hazardous-area approvals an additional galvanic isolation stage is required outside the IC.
Được đề xuất
Thermocouple and RTD Temperature Measurement
With its internal ±2 °C die temperature sensor and 12-bit resolution the MAX1238LEEE+T enables a single IC to handle both external thermocouple measurements and cold-junction compensation. Differential-mode operation lets two RTDs be read simultaneously via a ratiometric excitation. The 50 ppm/°C internal reference is suitable for an external RTD excitation buffer; for higher-accuracy thermocouple work, replace it with a MAX6325-class external reference on the REF pin. Pairing with a low-noise front-end analog input filter (10 Hz Sallen-Key 2nd-order) brings effective resolution near 14 bits after averaging.
Được đề xuất
Portable Handheld Test Instruments
The MAX1238LEEE+T's compact 16-QSOP footprint (0.0256 in²) and 670 µA at full speed suit handheld DMM and oscilloscope probes that need many input channels in a tight enclosure. Its 94.4 ksps throughput captures audio-band signals adequately for HVAC, vibration, and PQ measurements. The integrated reference removes two external components per ADC, BOM-count-critical in cost-sensitive consumer test gear. Pairing the part with a small Cortex-M0 MCU is common; I2C 7-bit addressing lets up to eight MAX1238s share a bus, expanding front-end channel count without extra MCUs.
Được đề xuất
Medical Instrumentation Front-Ends
The MAX1238LEEE+T's 12-bit resolution, low power consumption, and ±1 LSB linearity make it relevant to battery-powered patient-monitoring front-ends where leakage current and channel density both matter. Internal temperature sensing enables patient-side skin-temperature telemetry without extra thermistors. The 94.4 ksps throughput handles multi-lead ECG digitisation at 1 kHz per channel after downsampling. The IC is graded -40 °C to +85 °C, suitable for non-implantable medical designs; for IEC 60601 patient leakage requirements, design the chassis analog ground plane carefully with isolated DC-DC converters feeding AVDD/DVDD.
Được đề xuất
HVAC and Environmental Sensor Nodes
Wireless and wired HVAC sensor nodes use the MAX1238LEEE+T to digitize multiple analog humidity, CO2, VOC, and thermistor signals while reading the on-chip die temperature for self-calibration. The 0.5 µA shutdown current allows the node to wake every 30 s, sample all channels, then sleep, hitting multi-year coin-cell battery life targets. With 12-bit resolution over the 0-4.096 V input range the LSB size is approximately 1 mV, sufficient for thermistor-based humidity sensors whose output is roughly 1-3.5 V. The internal reference is precise enough for HVAC-grade calibration; for ashrae-rated building sensors an external REF becomes worthwhile.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho MAX1238LEEE+T — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | MAX1238EEE+T | MAX1139MEEE+T | MAX1239LEEE+ |
|---|---|---|---|---|
| Package | 16-QSOP | 16-QSOP - same | 16-QSOP - same | 16-QSOP - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 12 bit | 12 bit | 10 bit | 12 bit |
| Analog Inputs | 6 or 12 channels | 6 or 12 channels | 6 or 12 channels | 6 or 12 channels |
| Max Sampling Rate | 94.4 ksps | 94.4 ksps | 94.4 ksps | 94.4 ksps |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 2.7 V to 3.6 V |
| Internal Reference | 4.096 V, 50 ppm/°C | 4.096 V, 50 ppm/°C | 4.096 V | 4.096 V |
| Interface | I2C, 400 kHz | I2C, 400 kHz | I2C, 400 kHz + 1.7 MHz HS mode | I2C, 400 kHz + 1.7 MHz HS mode |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C |
Bảo phân biệt quan trọng
- 12-bit resolution with on-chip 4.096 V reference in 16-QSOP (vsMAX1139MEEE+T)
- Industrial temperature grade -40 °C to +85 °C with software configurable 6/12 channels (vsMAX1238EEE+)
- 0.5 µA software shutdown with internal temperature sensor (vsMAX1039LEEE)
- 94.4 ksps throughput with internal track/hold (vsGeneric 12-bit I2C ADCs)
Ghi chú thiết kế
The MAX1238LEEE+T draws 670 µA at full 94.4 ksps throughput but drops to 0.5 µA in software shutdown. For battery-powered designs sequence wake / sample / convert / shutdown in the I2C-driven setup register rather than gating the supply. Estimated: at one conversion every 30 s the average supply current is roughly 5 µA, dominated by the I2C pull-up leakage. Always drive both AVDD and DVDD from low-noise LDOs - the part shares an internal 4.096 V reference node and a noisy AVDD will manifest as amplified INL/DNL errors.
Place the 0.1 µF + 10 µF decoupling pair on AVDD and DVDD within 3 mm of the device pins, on the same board layer with short, wide traces. Use a single-point ground joining analog ground (AGND) and digital ground (DGND) only at pin 10; never use a ground-loop trace. Route AIN traces symmetrically for differential-pair operation and guard them with analog ground. The 16-QSOP exposed lead-frame is not a thermal pad; thermal performance in this package relies on minimizing AVDD-side copper losses rather than heatsinking.
The 12-bit ADC achieves best dynamic performance when input source impedance is below 1 kΩ. For higher-impedance sensors (e.g. pH probes, biased thermistors) add a low-noise op-amp buffer (OPA350-class) in front of the AIN pin. The internal track/hold settles in roughly 200 ns; let SCL frequency stay at 400 kHz max when using high source impedance to avoid coupling-induced non-linearity. The on-chip ADC has ±1 LSB INL/DNL; achieving 12 ENOB in production layouts requires attention to power-rail ferrite beads and slot-shield patterns on the analog ground plane.
Do not exceed 5.5 V on AVDD - the part has no internal clamp and overvoltage will damage the reference. Do not leave REF floating: even when overdriven externally, the REF pin should be decoupled with at least 0.1 µF + 4.7 µF to limit reference noise. Avoid burst-mode I2C transactions without proper setup-register sequencing - improper transitions can leave the ADC in a non-defined state. Always read the datasheet's setup-register bit definitions before adding new channel configurations.
Ground-plane stitching vias around AIN traces prevent cross-talk; for designs with multiplexer inputs that swing more than 4 V, allow guard traces driven by analog ground. The internal I2C pull-up resistors are NOT included - external 2.2 kΩ to 10 kΩ pull-ups must be sized per bus capacitance. Designed for 5 V AVDD/2.7-5 V DVDD; using it on a 3.3 V-only rail requires review against the 2.7-3.6 V MAX1237/MAX1239 datasheet instead.
Thông tin tuân thủ
RoHS compliant per the Analog Devices (formerly Maxim Integrated) MAX1238 product page. Not AEC-Q100 - choose an AEC-Q100 qualified variant from the MAX12xx automotive family for vehicle applications. Lead-free and halogen-free per the manufacturer datasheet.
