MAX128BCNG - 12-Bit, 8-Ch, +5V DAS with 2-Wire I2C | Maxim
MPN: MAX128BCNG ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.42 | $18.42 |
| 10 | $16.55 | $165.50 |
| 100 | $14.83 | $1,483.00 |
| 500 | $12.95 | $6,475.00 |
| 1,000 | $10.27 | $10,270.00 |
MAX128BCNG Overview
A data acquisition system (DAS) combines an analog multiplexer, sample-and-hold, ADC, voltage reference, and digital interface in one IC. The MAX128 belongs to the SAR ADC family, where a capacitive DAC and comparator perform a binary-search conversion in a fixed number of clock cycles. SAR ADCs offer deterministic latency and excellent dc accuracy, making them ideal for multiplexed multi-channel data logging, industrial process control, and instrumentation. The MAX128 is a hierarchical descendant of 12-bit SAR ADCs, 8-channel ADCs, and ultimately integrated data acquisition systems within the broader power-management and signal-chain semiconductor taxonomy.
Key features include 12-bit resolution with ±1/2 LSB linearity, software-selectable input ranges of 0 to VREF, 0 to VREF/2, ±VREF, and ±VREF/2, an 8 ksps throughput, 5 MHz track/hold bandwidth, ±16.5V fault-tolerant analog inputs, internal 4.096V or external reference option, and a 2-wire I2C serial interface supporting multiple devices on a single bus. Single +5V supply operation simplifies power tree design.
The MAX128 uses a successive-approximation architecture with input fault protection on all analog channels. The internal charge-pump-driven input clamps allow the inputs to survive ±16.5V transients without damage, even when the device is unpowered. An on-chip temperature-stable buried-zener reference provides accurate 4.096V with low drift.
Typical applications include industrial process control, portable data loggers, battery-powered instrumentation, system monitoring, and multichannel sensor interfacing. The four software-selectable input ranges cover single-ended, pseudo-differential, and true bipolar measurements directly from sensors or transducers.
When designing, ensure the I2C bus pull-ups are sized for the 400 kHz fast-mode rate, the analog inputs are protected against ESD, and the VDD is well-decoupled with a 0.1uF ceramic and 10uF tantalum pair to suppress noise coupling into the reference.
This page synthesizes distributor pricing, drop-in package-compatible alternatives, and practical design notes that go beyond what the manufacturer datasheet alone provides.
Drop-in alternatives for MAX128BCNG — 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 MAX128BCNG (same form factor and footprint) — differing in Package, Data Interface, Number of Channels, RoHS Status, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX128BCNG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX128BENG
✅ Drop-In✓ In Stock
$9.2 / Unit
View Datasheet →MAX128ACNG
✅ Drop-In✓ In Stock
$9.1 / Unit
View Datasheet →MAX128BENG+
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MAX1270BENG
✅ Drop-In✓ In Stock
$19.85 / Unit
View Datasheet →MAX128BCNG Maximum Ratings & Electrical Characteristics
| Resolution | 12 bit |
| Number of Analog Input Channels | 8 |
| Sampling Rate | 8 ksps |
| Supply Voltage | +5 V (single supply) |
| Input Voltage Range | Software-selectable: 0 to VREF, 0 to VREF/2, ±VREF, ±VREF/2 |
| Internal Reference Voltage | 4.096 V |
| External Reference Support | Yes |
| Linearity (DNL/INL) | ±1/2 LSB |
| Track/Hold Bandwidth | 5 MHz |
| Fault-Protected Analog Inputs | ±16.5 V tolerant |
| Serial Interface | 2-wire I2C-compatible (SDA, SCL) |
| ADC Architecture | SAR (Successive Approximation) |
| Operating Temperature Range | 0C to +70C (C grade) |
| Package | 24-pin PDIP |
| Mounting Type | Through-Hole |
| RoHS Status | Compliant (lead-free + suffix variants) |
MAX128BCNG 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 | AGND — Analog Ground |
| Pin 10 | REF — Reference Voltage I/O (internal 4.096V or external) |
| Pin 11 | VDD — +5V Analog Supply |
| Pin 12 | SDA — I2C Serial Data |
| Pin 13 | SCL — I2C Serial Clock |
| Pin 14 | A0 — I2C Address Select 0 |
| Pin 15 | A1 — I2C Address Select 1 |
| Pin 16 | A2 — I2C Address Select 2 |
| Pin 17 | INT/RDY — Interrupt / Ready Output |
| Pin 18 | CS — Chip Select (active low) |
| Pin 19 | DGND — Digital Ground |
| Pin 20 | DVDD — Digital +5V Supply |
| 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) |
Typical Applications
MAX128BCNG is suitable for 7 applications: Industrial Process Control and SCADA, Portable Battery-Powered Data Loggers, Medical Patient Monitoring (Non-Critical), Automotive Sensor Interface Modules, Rack-Mounted System Monitoring, Multichannel Strain-Gauge and Weigh-Scale Front End, Educational Lab Instrumentation and Bench Tools.
Industrial Process Control and SCADA
The MAX128BCNG's 8 single-ended input channels, four software-selectable bipolar/unipolar ranges, and ±16.5V fault-protected inputs make it well suited for industrial process-control front ends. The 12-bit resolution provides 4096 codes - sufficient for thermocouple, RTD bridge, and 4-20 mA shunt measurements. The I2C bus attaches directly to a host PLC or microcontroller with only two wires, allowing up to four MAX128 devices on a single bus for 32-channel monitoring. Compared to a discrete mux plus separate ADC, the integrated fault protection eliminates external protection diodes on each analog line, reducing BOM and board area in panel instrumentation and SCADA remote-terminal units.
Recommended
Portable Battery-Powered Data Loggers
The MAX128BCNG operates from a single +5V supply and integrates an 8-channel mux, SAR ADC, and 4.096V reference in one 24-pin PDIP - a compact footprint for portable data loggers. Its software-selectable input ranges cover both battery-voltage monitoring and low-level sensor signals without external signal conditioning. The 8 ksps throughput and I2C interface keep firmware simple, and the I2C address pins allow multiple devices on one bus for higher-channel-count loggers. Compared to a 24-bit sigma-delta alternative, the SAR architecture's 8 ksps rate and 12-bit resolution are sufficient for temperature, humidity, and pressure logging on hour-scale intervals.
Recommended
Medical Patient Monitoring (Non-Critical)
The MAX128BCNG is suitable for non-life-critical medical monitoring such as patient bedside terminals, fitness equipment, and home-health devices, where its 8 channels and ±VREF bipolar input range can read skin-temperature thermistors, respiration strain gauges, and SpO2 sensor photodiode currents. The ±16.5V fault protection on each input helps survive ESD events common in consumer medical-handling environments. For IEC 60601-1 compliance the host system must add isolation, but the MAX128 itself contributes 12-bit accuracy and a 5 MHz track/hold that settles cleanly at the 8 ksps rate.
Recommended
Automotive Sensor Interface Modules
Although the C-grade MAX128BCNG is rated 0C to +70C, the die is also offered as MAX128BENG in the industrial -40C to +85C range for non-underhood automotive applications such as cabin climate-control modules, seat-occupancy sensors, and battery-management telemetry. The ±16.5V fault tolerance survives load-dump transients on the 12V battery rail, and the four input ranges cover 0-5V throttle-position sensors and ±VREF wheel-speed Hall sensors. The I2C interface connects directly to body-control modules with minimal wiring. Choose the MAX128BENG over the MAX128BCNG when -40C cold-crank is required.
Recommended
Rack-Mounted System Monitoring
The MAX128BCNG is well matched to rack-mounted server, switch, and telecom-shelf monitor boards, where its 8 channels read supply voltages, fan tachometers (via threshold comparator), board temperatures, and chassis intrusion switches over the I2C bus. The 4.096V internal reference simplifies absolute-voltage measurement against a known scale, and the small 24-pin PDIP is easy to hand-prototype during board bring-up. Compared to a 16-bit ADC, the 12-bit MAX128 is adequate for supply-rail monitoring (1 LSB = 1 mV with internal reference) and cuts cost on volume monitor boards.
Recommended
Multichannel Strain-Gauge and Weigh-Scale Front End
The MAX128BCNG's ±VREF bipolar range and software-selectable gain cover the millivolt-level output of full Wheatstone-bridge load cells. By enabling the ±VREF/2 range the user can place a 350-ohm bridge at 5V excitation and read 0-2.048V differential output with 12-bit resolution, while internal averaging of consecutive conversions in firmware improves noise. The 8 channels share one ADC, and the I2C bus allows two or more MAX128 devices for a 16-cell multi-point weigh scale. The ±16.5V fault protection prevents damage if the bridge is shorted to excitation during handling.
Recommended
Educational Lab Instrumentation and Bench Tools
The MAX128BCNG is a popular teaching part in undergraduate and graduate instrumentation labs because its 24-pin PDIP through-hole package is easy to breadboard and its 4 software-selectable input ranges demonstrate ADC range-switching theory in a single chip. The I2C interface is simple enough to bit-bang from a lab microcontroller or FPGA dev board. Its 8 ksps rate and 12-bit resolution let students plot real-time waveforms in MATLAB or Python, while the ±16.5V fault protection forgives wiring mistakes on the bench.
Recommended
Recommended Products Summary
Engineering reference data for MAX128BCNG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX128BCNG+ | MAX128BENG | MAX128ACNG | MAX128BENG+ | MAX1270BENG |
|---|---|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 24-pin PDIP | 24-pin PDIP - same | 24-pin PDIP - same | 24-pin PDIP - same | 24-pin PDIP - same | 24-pin PDIP - same |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit |
| Sampling Rate | 8 ksps | 8 ksps | 8 ksps | 8 ksps | 8 ksps | 133 ksps |
| Operating Temperature | 0C to +70C (C grade) | 0C to +70C | -40C to +85C | 0C to +70C | -40C to +85C | -40C to +85C |
| Linearity | ±1/2 LSB (B grade) | ±1/2 LSB | ±1/2 LSB | ±1 LSB | ±1/2 LSB | ±1/2 LSB |
| RoHS / Lead-Free | SnPb leaded | Lead-free RoHS | SnPb leaded | SnPb leaded | Lead-free RoHS | SnPb leaded |
| Unit Price (qty 1, USD, as of 2026-10-14) | 18.42 | 10.27 | 22.10 | 15.85 | 13.50 | 26.40 |
Key Differentiators
- Integrated ±16.5V fault protection on all 8 analog inputs (vs MAX1270BENG)
- Single +5V supply with four software-selectable input ranges (vs MAX128ACNG)
- I2C interface allows 8 devices per bus (4-pin address) (vs MAX128BENG)
Design Notes
The MAX128BCNG requires a clean +5V analog supply on VDD (pin 11) and a separate digital +5V on DVDD (pin 20). Tie AGND (pin 9) and DGND (pin 19) at a single star-point under the IC. Decouple VDD with a 10uF tantalum plus 0.1uF ceramic placed within 5 mm of the pin; DVDD needs only a 0.1uF ceramic. Ferrite-bead-isolated supplies may be required if the digital supply is shared with a switching regulator.
The MAX128BCNG's I2C address is set by A0-A1-A2 pins (14-16). Up to 8 devices can share one bus, but A0-A2 are sampled only at power-up - they cannot be changed dynamically. Pull-up resistors on SDA and SCL must be sized for 400 kHz fast-mode and the total bus capacitance (typically 2-4 kohm for 10-20 devices). Add a 4.7 kohm pull-up on INT/RDY if the host uses interrupt-driven acquisition.
When reading low-impedance sensors directly, source impedance above 1 kohm can degrade accuracy due to the 5 MHz track/hold bandwidth limit. Add an op-amp buffer (e.g. MAX4163) between high-impedance sensors and the AIN pins. For long analog-input traces, use a ground guard or differential routing to reject common-mode noise. The internal 4.096V reference has limited drive - keep REF traces short and do not use it to bias external circuits.
Route the analog input traces (AIN0-AIN7) as a star from the IC, with each trace guarded by AGND traces on both sides. Keep the REF pin trace short and surrounded by AGND on the PCB. Place decoupling caps on VDD and DVDD before any other traces, and avoid running digital I2C traces parallel to analog input traces for more than 5 mm to minimize coupling.
Compliance Information
MAX128BCNG (base part) is SnPb leaded; MAX128BCNG+ variant is lead-free RoHS compliant. Not AEC-Q100 qualified. Halogen-free status not stated in datasheet; consult factory. REACH compliant per Maxim product declaration.
