MAX1138KEEE+T - 12-Ch 10-Bit I2C ADC, 5V | Maxim Integrated
MPN: MAX1138KEEE+T ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.1 | $6.10 |
| 10 | $5.48 | $54.80 |
| 100 | $4.85 | $485.00 |
| 500 | $4.1 | $2,050.00 |
| 1,000 | $3.55 | $3,550.00 |
MAX1138KEEE+T Overview
An ADC (analog-to-digital converter) is a semiconductor device that converts continuous analog signals into discrete digital codes for processing by microcontrollers, DSPs, or FPGAs. Successive-approximation-register (SAR) ADCs such as the MAX1138 deliver deterministic latency, low power, and excellent DC accuracy, making them the workhorse for industrial sensor reading, battery monitoring, and instrumentation front-ends. The MAX1138 belongs to the broader SAR ADC > multi-channel data converter > signal chain IC > semiconductor hierarchy.
Key features include 12 analog input channels (11 single-ended plus differential), an internal 2.5V reference, software-configurable unipolar/bipolar input ranges, an external reference option for ratiometric measurements, and a hardware/software shutdown mode that drops supply current to 1 microA. The 16-pin SSOP (K package) measures approximately 4.9 mm x 3.9 mm with a 0.635 mm pitch, suiting compact designs where board area is at a premium.
The MAX1138 integrates track-and-hold, clock, and reference on-chip, eliminating external components and reducing BOM cost. Its I2C interface supports up to eight devices on a single bus via two address pins, simplifying multi-ADC systems. The wide 4.5V-5.5V supply range makes it directly compatible with 5V microcontrollers and legacy industrial rails.
Typical applications include industrial sensor monitoring (temperature, pressure, strain gauge bridges), portable instrumentation, patient monitoring devices, data-acquisition systems, and battery-powered measurement equipment. The 12-channel count is well suited to multi-zone HVAC controllers, PLC analog modules, and embedded control boards where many sensors share one ADC.
When designing with the MAX1138KEEE+T, ensure the I2C pull-up resistors match the bus speed - 4.7k for 400 kHz, 1k for 1.7 MHz High-Speed Mode. Add 0.1uF decoupling close to VDD and bypass the reference pin per the manufacturer datasheet. For highest absolute accuracy, use an external low-noise reference instead of the internal 2.5V bandgap.
This page synthesizes distributor pricing, drop-in alternatives sourced from manufacturer parametric data, and practical design notes that go beyond a single-datasheet reading.
Drop-in alternatives for MAX1138KEEE+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 MAX1138KEEE+T (same form factor and footprint) — differing in Input Type, Interface, Package, Supply Voltage.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1137KEEE+T
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MAX1139KEEE+T
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MAX1138KEEE+
✅ Drop-In✓ In Stock
$4.55 / Unit
View Datasheet →MAX1138KEEE-T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1238EEE+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1138KEEE+T Maximum Ratings & Electrical Characteristics
| Resolution | 10 bit |
| Number of Channels | 12 (11 single-ended / pseudo-differential) |
| Sampling Rate | 94.4 ksps |
| Supply Voltage | 4.5 V to 5.5 V |
| Supply Current (max sample rate) | 670 uA |
| Shutdown Current | 1 uA |
| Interface | I2C (2-wire), 400 kHz Fast Mode, 1.7 MHz High-Speed Mode |
| Address Select Pins | 2 (up to 4 selectable slave addresses) |
| Input Type | Single-ended, software-configurable unipolar/bipolar |
| Internal Reference | 2.5 V |
| External Reference Input | Yes |
| Package | 16-pin SSOP (K) |
| Operating Temperature | -40C to +85C |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited) |
| RoHS Status | Compliant |
| Conversion Architecture | SAR (Successive Approximation Register) |
MAX1138KEEE+T Pin Configuration
| Pin 1 | AIN0 — Analog input channel 0 |
| Pin 2 | AIN1 — Analog input channel 1 |
| Pin 3 | AIN2 — Analog input channel 2 |
| Pin 4 | AIN3 — Analog input channel 3 |
| Pin 5 | AIN4 — Analog input channel 4 |
| Pin 6 | AIN5 — Analog input channel 5 |
| Pin 7 | AIN6 — Analog input channel 6 |
| Pin 8 | AIN7 — Analog input channel 7 |
| Pin 9 | AIN8/COM — Analog input channel 8 / common reference for differential mode |
| Pin 10 | AIN9 — Analog input channel 9 |
| Pin 11 | SDA — I2C serial data |
| Pin 12 | SCL — I2C serial clock |
| Pin 13 | AD0 — I2C slave address select bit 0 |
| Pin 14 | AD1 — I2C slave address select bit 1 |
| Pin 15 | REF — Voltage reference input/output (internal 2.5V or external) |
| Pin 16 | VDD — Positive supply voltage (4.5V-5.5V) and substrate connection |
Typical Applications
MAX1138KEEE+T is suitable for 6 applications: Multi-Zone Industrial Sensor Monitoring, Portable Patient Monitoring Devices, HVAC Multi-Sensor Control Boards, Battery Management and Cell Monitoring, Data Acquisition Modules for Test Equipment, Smart Sensor Hubs and IoT Edge Nodes.
Multi-Zone Industrial Sensor Monitoring
The MAX1138KEEE+T's 12-channel input mux directly reads temperature, pressure, humidity, and flow sensors in factory automation panels where PLC analog modules must monitor dozens of field points. Each channel is software-selected, and the 94.4 ksps throughput allows polling all 12 inputs under 1 ms - fast enough for closed-loop control loops. The I2C interface shares the bus with other Maxim sensors and EEPROMs, reducing pin count on the host microcontroller. Designed with the part's 5V supply, designers can power the ADC and 5V analog signal-conditioning rails from the same 24V-to-5V LDO downstream of an industrial bus.
Recommended
Portable Patient Monitoring Devices
Battery-powered patient monitors demand low quiescent current and small board area - both satisfied by the MAX1138KEEE+T. Its 1 uA shutdown current preserves battery life between measurements, while 10-bit resolution is sufficient for SpO2, ECG lead-off detection, and temperature trends in wearable or bedside devices. The 16-pin SSOP footprint occupies roughly 19 mm², leaving room for analog signal conditioning, an MCU, and BLE radio on a compact PCB. Use the internal 2.5V reference to minimize external component count and BOM cost in this cost-sensitive medical segment.
Recommended
HVAC Multi-Sensor Control Boards
Commercial HVAC systems monitor return-air temperature, supply-air temperature, humidity, static pressure, and fan current across multiple zones - typically 8-12 analog inputs per controller board. The MAX1138KEEE+T handles all of these on a single ADC with software channel selection, eliminating external mux ICs and reducing BOM cost. Its -40C to +85C operating range covers equipment-room environments, and the I2C interface simplifies routing between the ADC, EEPROM setpoint storage, and host MCU. Compared to a discrete op-amp + ADC solution, the integrated reference and track-and-hold cut PCB area by 30-40%.
Recommended
Battery Management and Cell Monitoring
Multi-cell battery packs for e-bikes, portable tools, and uninterruptible power supplies need per-cell voltage monitoring that scales with cell count. The MAX1138KEEE+T's 12 channels read up to 12 Li-ion cells (or 24V/36V/48V lead-acid stacks through resistive dividers), and its 1 uA shutdown preserves quiescent current between scans. The 5V supply can be derived from a local LDO off the battery, eliminating an isolated supply rail. When combined with an external MOSFET-based cell-balancing circuit, the ADC serves as the analog front-end for a complete BMS in <100 mm² of PCB area.
Recommended
Data Acquisition Modules for Test Equipment
Compact USB or Ethernet data-acquisition modules targeting bench instrumentation benefit from the MAX1138KEEE+T's combination of 12 channels, 10-bit resolution, and I2C interface. An I2C-controlled multiplexer or a dedicated address lets four MAX1138s (48 channels total) share one bus, scaling with the module's channel count. With internal reference and track-and-hold, the analog front-end requires only input protection resistors and anti-alias capacitors - ideal for portable bench-top DAQ where calibration simplicity matters. The 4.5V-5.5V supply is compatible with USB-powered 5V rails after a ferrite bead for EMI isolation.
Recommended
Smart Sensor Hubs and IoT Edge Nodes
IoT edge nodes aggregate multiple analog sensors (light, sound, gas, vibration) into one wireless node, and the MAX1138KEEE+T provides the analog front-end with 12 channels and an I2C bus that connects directly to low-power wireless MCUs. The 1 uA shutdown extends battery life on energy-harvested or coin-cell-powered nodes. With 94.4 ksps burst mode, the ADC can sample transient events (vibration, current spikes) and return to deep sleep in microseconds. The combination of small SSOP package, low power, and I2C address expansion (4 devices per bus = 48 channels) makes it a strong fit for distributed sensor networks.
Recommended
Recommended Products Summary
Engineering reference data for MAX1138KEEE+T — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1137KEEE+T | MAX1139KEEE+T | MAX1138KEEE+ | MAX1138KEEE-T | MAX1238EEE+T |
|---|---|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 16-pin SSOP (K) | 16-pin SSOP (K) - same | 16-pin SSOP (K) - same | 16-pin SSOP (K) - same | 16-pin SSOP (K) - same | 16-pin QSOP (E) - different |
| Resolution | 10 bit | 10 bit | 10 bit | 10 bit | 10 bit | 12 bit |
| Number of Channels | 12 | 12 | 4 | 12 | 12 | 12 |
| Supply Voltage | 4.5V to 5.5V | 2.7V to 3.6V | 2.7V to 3.6V | 4.5V to 5.5V | 4.5V to 5.5V | 4.5V to 5.5V |
| Interface | I2C 2-wire | I2C 2-wire | I2C 2-wire | I2C 2-wire | I2C 2-wire | I2C 2-wire |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Key Differentiators
- Pin-compatible 3.3V drop-in variants available in same family (vs MAX1137KEEE+T)
- 12-channel count exceeds 3.3V sibling MAX1139 (4 channels) (vs MAX1139KEEE+T)
- Bulk-pack and 7-inch reel variants share identical die (vs MAX1138KEEE+ (bulk))
- 12-bit upgrade path exists with QSOP-16 package (vs MAX1238EEE+T)
Design Notes
Place a 0.1uF X7R ceramic decoupling capacitor within 3 mm of the VDD pin, with a 10uF bulk capacitor on the same rail. For systems where the analog supply is shared with digital logic, add a ferrite bead between the digital 5V rail and the ADC VDD to attenuate switching noise. The MAX1138 draws 670uA at 94.4 ksps but only 1uA in shutdown, so routing the enable bit to a microcontroller GPIO can drop quiescent current by three orders of magnitude during idle periods.
Route analog input traces away from the I2C SCL/SDA lines and from any switching converter or PWM trace. Use a ground plane under the ADC and place the part's exposed pad (when present) on a low-impedance ground pour to reduce thermal noise and digital coupling. For long input traces, add a small RC anti-alias filter (typically 1 kohm + 100 pF) close to the analog input pin; the -3 dB corner should sit well above the highest frequency of interest but well below the Nyquist rate (47.2 kHz for 94.4 ksps).
Source impedance seen at each analog input should remain below 5 kohm for full 10-bit accuracy at the maximum sampling rate; higher source impedance introduces voltage drop across the internal track-and-hold switch. If the source impedance is higher than 5 kohm, either buffer with an op-amp or reduce the sampling rate. For ratiometric measurements using the internal reference, pair the reference with a 0.1uF bypass capacitor at the REF pin to suppress noise.
Do not leave unused analog inputs floating - tie them to VDD or GND to prevent the internal mux from injecting crosstalk into adjacent active channels. Verify the I2C slave address by tying AD0 and AD1 to GND, VDD, SDA, or SCL per the datasheet; miswiring either address pin places two devices at the same address and causes bus arbitration failures. The 'K' suffix denotes SSOP; do not confuse this 16-pin SSOP package with the 16-pin QSOP ('E' suffix) - the MAX1238EEE+T is QSOP and uses a different PCB land pattern.
Compliance Information
RoHS and REACH compliant per Maxim Integrated (Analog Devices) environmental policy. Not AEC-Q100 qualified - not intended for automotive under-hood applications.
