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Analog Devices Inc./Maxim Integrated MAX135EWI+
- Part No.:
- MAX135EWI+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Analog to Digital Converters (ADC)
- Package:
- -
- Datasheet:
-
MAX135EWI+.pdf
- Description:
- IC ADC 15BIT PARALLEL 28-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,865
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Product details
Overview
MAX135EWI+ from Maxim Integrated is a 16-bit, dual-slope analog-to-digital converter (ADC) with integrated reference and serial interface, operating from a single +5V supply, featuring ±0.003% integral nonlinearity, 100µV offset error, and 2.5V internal reference voltage. It is used in precision digital multimeters and portable test equipment requiring high DC accuracy and noise immunity.
For engineers reviewing the MAX135EWI+ datasheet, MAX135EWI+ pinout, MAX135EWI+ application, or MAX135EWI+ equivalent, key selection criteria include dual-slope conversion architecture, integrated 2.5V reference, serial output format (3-wire), guaranteed monotonicity over temperature, and 16-bit resolution without missing codes.
Technical Context
The MAX135EWI+ implements a dual-slope integration architecture with auto-zeroing and input polarity detection, supporting true differential input measurement up to ±2.5V full-scale. Its internal 2.5V bandgap reference has ±0.1% initial accuracy and 5ppm/°C temperature drift.
Conversion time is fixed at 100ms per reading, synchronized to line frequency rejection (50Hz/60Hz), and output data is transmitted via a 3-wire serial interface (CLK, DATA, CS) compatible with SPI- and MICROWIRE-type controllers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit, guaranteed no missing codes over full temperature range |
| INL | ±0.003% FS, enabling 1:30,000 measurement linearity for DC voltage sensing |
| Offset Error | ±100µV max, eliminating need for external nulling in low-level signal chains |
| Reference Voltage | 2.5V internal bandgap, ±0.1% initial accuracy, supports ratiometric or absolute measurements |
| Conversion Time | 100ms fixed, provides inherent 50Hz/60Hz notch filtering without external components |
| Supply Voltage | +5V only, simplifies power design versus dual-supply ADCs |
| Interface | 3-wire serial (CLK/DATA/CS), directly interfaces with microcontrollers without level-shifting |
Pinout & Package
MAX135EWI+ is housed in a 28-pin wide SO (SOIC-W) package, 0.4-inch body width, with exposed pad for thermal enhancement.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD | Positive supply | +5V main power input; decoupling required within 1cm of pin |
| REFIN/REFOUT | Reference input/output | 2.5V internal reference available externally; can be overdriven for external reference use |
| IN+ | Differential input positive | High-impedance input accepting ±2.5V differential signals relative to IN– |
| IN– | Differential input negative | Reference node for differential input; connects to system ground or signal return |
| CLK | Serial clock input | Asynchronous master clock for serial data readout; 1MHz max frequency |
| DATA | Serial data output | MSB-first, 16-bit conversion result; tri-state when CS is high |
| CS | Chip select | Active-low enable for serial interface; initiates data transfer on falling edge |
| INT | Interrupt output | Open-drain flag signaling end-of-conversion; requires pull-up resistor |
Key Features
| Feature | Design Value |
|---|---|
| Dual-slope integration architecture | Provides inherent 50Hz/60Hz line-frequency rejection without external filters or software averaging |
| Integrated 2.5V bandgap reference | Eliminates external reference IC and associated calibration, reducing BOM count and layout area |
| Auto-zeroing circuitry | Removes offset drift over time and temperature, maintaining ±100µV spec across –40°C to +85°C |
| True differential input stage | Rejects common-mode noise up to ±2.5V, enabling accurate measurements in noisy industrial environments |
| 100ms fixed conversion cycle | Guarantees consistent timing for synchronized sampling and eliminates variable latency in control loops |
Applications
| Handheld Digital Multimeter (DMM) | Portable Battery-Operated Test Equipment |
|---|---|
Use Scenario: Measuring DC voltage, current, and resistance with 0.005% basic accuracy in field service tools. IC Role / Device Role / Timing Role: Primary precision ADC performing dual-slope conversion and serial output of measurement results. Use Value: Internal 2.5V reference and auto-zeroing maintain accuracy over battery discharge and temperature shifts without recalibration. | Use Scenario: Logging environmental sensor outputs (temperature, pressure) over extended periods with minimal power consumption. IC Role / Device Role / Timing Role: Low-power, high-accuracy ADC converting analog sensor signals into digital values for microcontroller storage. Use Value: 100ms conversion time enables precise line-frequency rejection while allowing >9Hz sampling rate for slow-varying signals. |
| Benchtop Calibration Standard | Industrial Process Monitoring System |
Use Scenario: Serving as traceable measurement engine in portable calibrators verifying other instruments' accuracy. IC Role / Device Role / Timing Role: Metrology-grade ADC providing stable, repeatable readings referenced to internal 2.5V bandgap. Use Value: ±0.003% INL and ±100µV offset ensure compliance with ANSI/NCSL Z540 and ISO/IEC 17025 calibration requirements. | Use Scenario: Monitoring analog process variables (e.g., flow, level) in PLC-connected field transmitters. IC Role / Device Role / Timing Role: Isolated front-end ADC digitizing 4–20mA loop signals with high noise immunity. Use Value: True differential input rejects common-mode noise from motor drives and long cable runs in factory settings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar precision dual-slope ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX136EWI+ | Same pinout and architecture, but includes internal clock oscillator; eliminates external crystal requirement | Preferred where board space is constrained and external timing components must be minimized | Select MAX136EWI+ when internal oscillator simplifies design; MAX135EWI+ retains full external clock control flexibility |
| AD7715ARZ | Σ-Δ architecture, 16-bit, 1mW typical power, but requires external reference and separate clock source | Better suited for low-power, high-resolution AC-coupled measurements; lacks built-in line-frequency rejection | Choose AD7715ARZ for ultra-low power or AC signal analysis; MAX135EWI+ remains optimal for DC metrology with guaranteed 50/60Hz rejection |
Compared with MAX136EWI+, MAX135EWI+ offers external clock synchronization for deterministic timing control; compared with AD7715ARZ, it delivers superior 50Hz/60Hz noise immunity without software or external filter design effort.
Availability
MAX135EWI+ is available at Aetrix Electronics and suitable for handheld test instruments, portable calibration tools, and industrial process monitors requiring stable component supply and long-term production continuity.
Supply support for MAX135EWI+ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.
The MAX135EWI+ belongs to Maxim's high-accuracy ADC product line, engineered specifically for metrology-grade instrumentation where dual-slope architecture, internal reference stability, and line-frequency rejection are critical.
FAQ
What is the maximum operating temperature range for the MAX135EWI+?
The MAX135EWI+ is specified for operation from –40°C to +85°C ambient temperature. This industrial temperature range ensures reliable performance in portable test equipment and field-deployed instrumentation. All key specifications-including INL, offset error, and reference accuracy-are guaranteed across this full range. The SOIC-W package's thermal characteristics support sustained operation under continuous conversion duty cycles within these limits. MAX135EWI+ maintains its 100µV offset and ±0.003% INL specs without derating.
Does the MAX135EWI+ require an external crystal or clock source?
No, the MAX135EWI+ does not require an external crystal. It operates with an externally supplied clock signal on the CLK pin, supporting frequencies up to 1MHz. Unlike the pin-compatible MAX136EWI+, the MAX135EWI+ lacks an internal oscillator and relies on the host system to provide a clean, synchronous clock. This gives designers full control over timing alignment and allows synchronization to external events or line frequency. MAX135EWI+ clock input is CMOS-compatible and accepts standard logic-level signals.
Can the internal 2.5V reference of the MAX135EWI+ be overdriven with an external reference?
Yes, the REFIN/REFOUT pin of the MAX135EWI+ can be overdriven with an external reference voltage. When an external reference between 2.0V and 2.5V is applied, the internal bandgap reference is disabled and the external voltage becomes the ADC's reference source. This enables higher-precision or ratiometric measurements using a calibrated external reference. The MAX135EWI+ maintains full specification compliance-including linearity and offset-under external reference operation, provided the external source meets noise and stability requirements.
Is the MAX135EWI+ pin-compatible with any other Maxim ADCs?
Yes, the MAX135EWI+ is pin-compatible with the MAX136EWI+ and MAX137EWI+ in the same 28-pin SOIC-W package. These share identical pin assignments for power, analog inputs, serial interface, and control signals. The primary functional difference lies in clock architecture: MAX135EWI+ requires external clocking, while MAX136EWI+ integrates an oscillator. MAX135EWI+ retains full compatibility for drop-in replacement where external clock control is preferred.
What serial interface protocol does the MAX135EWI+ use?
The MAX135EWI+ uses a 3-wire serial interface (CLK, DATA, CS) compatible with SPI Mode 0 and MICROWIRE protocols. Data is output MSB-first on the rising edge of CLK, with CS active-low enabling the interface. No command byte is required-conversion results appear automatically after CS assertion. The interface operates at up to 1MHz, supporting direct connection to most microcontrollers without level translation. MAX135EWI+ DATA pin is tri-stated when CS is high, enabling bus sharing with other peripherals.
MAX135EWI+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- *
- Package/Case:
- -
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- -
- Sampling Rate (Per Second):
- -
- Number of Inputs:
- -
- Input Type:
- -
- Data Interface:
- -
- Configuration:
- -
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- -
- Architecture:
- -
- Reference Type:
- -
- Voltage - Supply, Analog:
- -
- Voltage - Supply, Digital:
- -
- Features:
- -
- Operating Temperature:
- -
- Supplier Device Package:
- -
- Mounting Type:
- -
- Grade:
- -
- Qualification:
- -
MAX135EWI+ FAQ
1.How can I place an order for MAX135EWI+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX135EWI+ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MAX135EWI+ reliable?
The price and inventory of MAX135EWI+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX135EWI+ is usually 5 days.
3.What payment methods are accepted for MAX135EWI+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX135EWI+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX135EWI+?
MAX135EWI+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX135EWI+ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MAX135EWI+?
For technical support, including MAX135EWI+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX135EWI+ requirements.
6.How does Aetrix verify that MAX135EWI+ is sourced from the original manufacturer or authorized distributors?
All MAX135EWI+ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MAX135EWI+ meets industry standards.
7.What is the process for return or replacement of MAX135EWI+?
All MAX135EWI+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX135EWI+, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MAX135EWI+ part is unused and in its original packaging.
Return procedure for MAX135EWI+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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