MAX121CWE+ - 14-Bit 308ksps ADC | Maxim Integrated
MPN: MAX121CWE+ ✓ ActiveMAX121CWE+ Overview
An ADC is a data-acquisition semiconductor that converts an analog voltage into a digital value. The MAX121 belongs to the SAR ADC family, where a successive-approximation register compares the sampled input against an internal DAC during each conversion. In the broader hierarchy, it is a converter ADC, data-conversion IC, and analog-to-digital converter within the semiconductor category.
The principal performance figures are 14-bit resolution, 308ksps conversion throughput, and 78dB signal-to-noise-and-distortion ratio. The MAX121 accepts a single-ended input and provides a DSP interface suited to serial data acquisition. Its integrated reference uses a buried-zener structure, while the track-and-hold front end reduces the need for external analog sampling circuitry. A nominal -5.00V internal reference is identified in the manufacturer datasheet.
According to the MAX121 manufacturer datasheet, the reference output at VREF must be bypassed to AGND with a 0.1uF ceramic capacitor in parallel with a 22uF or greater electrolytic capacitor. The electrolytic capacitor must have an equivalent series resistance of 100mOhm or less. This stability requirement is important because reference-network impedance affects ADC accuracy and noise performance.
Typical uses include industrial process monitoring, precision sensor acquisition, laboratory measurement equipment, DSP front ends, and embedded control systems. The serial interface can reduce wiring in multichannel measurement equipment, although the MAX121 itself is a one-input converter and may require multiplexing when several analog channels must be measured.
For a new design, preserve the manufacturer reference-bypass topology and keep the analog input path short to minimize conversion error and noise pickup. The primary trade-off is throughput: 308ksps is suitable for fast acquisition but should be checked against signal bandwidth, filtering requirements, and the update rate needed by the downstream DSP.
This page combines verified manufacturer specifications, distributor availability information, packaging details, and same-family replacement guidance. It also identifies unresolved pricing, lifecycle, and package-rotation data explicitly rather than presenting unverified values as facts.
Drop-in alternatives for MAX121CWE+ — 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 MAX121CWE+ (same form factor and footprint) — differing in Internal Reference, Package.
MAX121EWE+
✅ Drop-InContact for price
View Datasheet →MAX121EWE
✅ Drop-In📋 Reference alternative (not in catalog)
MAX121CWE
✅ Drop-In📋 Reference alternative (not in catalog)
MAX121CWE+ Maximum Ratings & Electrical Characteristics
| ADC Type | Successive-approximation register (SAR) |
| Resolution | 14 bit |
| Sampling Rate | 308 ksps |
| Signal-to-Noise-and-Distortion Ratio | 78 dB |
| Input Architecture | Single ended |
| Input Channel Count | 1 channel |
| Process Technology | BiCMOS |
| Data Interface | Serial DSP interface |
| Internal Reference | Low-drift, low-noise buried-zener voltage reference |
| Internal Reference Voltage | -5.00 V |
| Sample-and-Hold | On-chip track-and-hold |
| Analog Supply Voltage | 5 V |
| Package | 16-pin WSOIC |
| Package Width | 0.295 inch, 7.50 mm |
| Reference Bypass Capacitor | 0.1 uF ceramic in parallel with 22 uF or greater electrolytic |
| Reference Capacitor Maximum ESR | 100 mOhm or less |
| RoHS Status | Compliant |
| Lead-Free Status | Lead-free |
MAX121CWE+ 0.295 inch, 7.50 mm Pin Configuration Guide
Pin configuration for MAX121CWE+ (0.295 inch, 7.50 mm package). This analog component features input, output, and power supply pins. Refer to the manufacturer datasheet for offset null, compensation, and enable pin configurations. Ideal for signal conditioning and amplifier circuits.
No detailed pinout data available for MAX121CWE+.
Refer to the datasheet for full pin configuration.
Typical Applications
MAX121CWE+ is suitable for 6 applications: Industrial Process Monitoring, Precision Sensor Acquisition, DSP-Controlled Data Acquisition, Laboratory Measurement Equipment, Portable Battery-Powered Instruments, Embedded Control and Monitoring.
Industrial Process Monitoring
The MAX121CWE+ fits industrial process-monitoring front ends that require repeatable conversion of a conditioned sensor voltage. Its 14-bit resolution and 78dB SINAD provide useful dynamic range, while 308ksps throughput allows several conversions during each measurement cycle. Place the ADC behind a low-noise amplifier and input filter, and bypass its -5.00 V buried-Zener reference with the specified 0.1uF ceramic and 22uF-or-greater electrolytic network. The single-ended input supports multiplexed process channels, although channel-switching time and settling must be included in the acquisition design.
Recommended
Precision Sensor Acquisition
The MAX121CWE+ is appropriate for low-level sensor signals that have been amplified and filtered before digitization. The 78dB SINAD specification supports a cleaner distinction between signal and quantization noise than a lower-resolution converter, while the integrated track-and-hold reduces the external sampling burden. Its 308ksps rate is substantially faster than typical temperature or pressure transducer bandwidth, allowing multiple readings for averaging. Designers should still account for sensor noise, input settling, reference stability, and the 100mOhm-or-less ESR requirement for the reference electrolytic capacitor.
Recommended
DSP-Controlled Data Acquisition
The MAX121CWE+ is suited to DSP-controlled acquisition systems because it offers a serial DSP interface and a throughput of 308ksps. A DSP can issue conversion commands, receive digital results, and perform filtering without requiring a parallel ADC bus. The 14-bit output word and 78dB SINAD provide useful headroom for waveform capture and process-control calculations. Interface timing and logic levels must be checked against the selected DSP, while the analog input should remain short, shielded when necessary, and referenced cleanly to the converter's analog ground.
Recommended
Laboratory Measurement Equipment
The MAX121CWE+ can serve as the measurement converter in laboratory instruments that digitize a conditioned analog input at up to 308ksps. Its 14-bit resolution supports useful precision without requiring an external reference DAC, and the integrated buried-Zener reference simplifies instrument architecture. The converter is still a single-input part, so a precision multiplexer may be needed for multiple input ranges. Layout should separate sensitive analog routing from digital interface traces, and the required reference bypass components should be placed close to VREF and AGND.
Recommended
Portable Battery-Powered Instruments
The MAX121CWE+ is useful in portable measurement equipment where low converter power consumption and integrated reference circuitry reduce component count. Its single-ended input and serial interface simplify board routing, while 308ksps throughput supports responsive sampling without operating continuously at the maximum rate. A battery-powered design must still account for analog-supply regulation, reference startup behavior, and input quiescent current. Power gating should avoid disturbing the reference network during sensitive measurements, and the PCB should provide a quiet ground and short reference return path.
Recommended
Embedded Control and Monitoring
The MAX121CWE+ supports embedded control systems that monitor an analog process variable and feed the result to a microcontroller or DSP. At 308ksps, the ADC can sample faster than most control-loop sensors, allowing averaging or diagnostic sampling while keeping the controller bus compact. The 78dB SINAD and 14-bit resolution help preserve small signal details, but the analog front end determines whether those converter capabilities are actually realized. Firmware should include range checks and settling delays after any input multiplexing, while the reference network must follow the manufacturer's ESR requirement.
Recommended
Recommended Products Summary
Engineering reference data for MAX121CWE+ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX121EWE+ | MAX121EWE | MAX121CWE |
|---|---|---|---|---|
| Package | 16-pin WSOIC | 16-pin WSOIC | 16-pin WSOIC | 16-pin WSOIC |
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Resolution | 14 bit | 14 bit | 14 bit | 14 bit |
| Sampling Rate | 308 ksps | 308 ksps | 308 ksps | 308 ksps |
| SINAD | 78 dB | 78 dB | 78 dB | 78 dB |
| Input Architecture | Single ended, 1 channel | Single ended, 1 channel | Single ended, 1 channel | Single ended, 1 channel |
| Process Technology | BiCMOS | BiCMOS | BiCMOS | BiCMOS |
| Internal Reference | Low-drift, low-noise buried-Zener reference, -5.00 V | Low-drift, low-noise buried-Zener reference | Low-drift, low-noise buried-Zener reference | Low-drift, low-noise buried-Zener reference |
Key Differentiators
- High conversion throughput (vs MAX121EWE+)
- Integrated precision reference (vs MAX121EWE)
- Compact 16-pin conversion platform (vs MAX121CWE)
Design Notes
Use the manufacturer reference network exactly: connect a 0.1uF ceramic capacitor and a 22uF-or-greater electrolytic capacitor from VREF to AGND, with electrolytic ESR at or below 100mOhm. Place both components close to their specified pins and use a low-impedance analog-ground return. Substituting a generic reference bypass arrangement can impair converter stability and reduce the effective accuracy represented by the 14-bit, 78dB SINAD specification.
Keep the single-ended analog input trace short, keep it away from serial-interface switching nodes, and provide a quiet ground connection for AGND. The 308ksps conversion capability does not eliminate the need for an analog filter because out-of-band noise and source-impedance settling can affect each conversion. Check the source impedance and acquisition timing in the manufacturer datasheet before adding input capacitance that could prevent full settling.
Do not treat MAX121CWE, MAX121CWE+, MAX121EWE, and MAX121EWE+ as interchangeable solely because their names are similar. The verified excerpts identify the family and package, but they do not provide the complete grade, temperature, and ordering information needed to establish drop-in equivalence. Confirm the exact MPN, pin definitions, operating-temperature limits, and acquisition timing in the manufacturer datasheet before changing a released BOM.
Compliance Information
The verified TrustCompo listing describes MAX121CWE+ as RoHS-compliant, lead-free, and green. No verified AEC-Q100, REACH, halogen-free, or conflict-minerals declaration was supplied.
