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Analog Devices Inc./Maxim Integrated MAX1391ETB+
- Part No.:
- MAX1391ETB+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
MAX1391ETB+.pdf
- Description:
- ADC, SUCCESSIVE APPROXIMATION, 8
- Quantity:
- Payment:
- Shipping:
Inventory:4,940
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Product details
Overview
MAX1391ETB+ from Maxim Integrated is an 8-bit, true-differential successive-approximation register (SAR) analog-to-digital converter (ADC) operating from +1.5V to +3.6V supply. It delivers 416ksps throughput, ±0.2 LSB INL/DNL, and 49dB SINAD at 100kHz input with external reference support (0.6V to VDD). Designed for ultra-low-power portable data acquisition, it features AutoShutdown™ between conversions and a 5MHz SPI-/QSPI-/MICROWIRE-compatible 3-wire serial interface.
For engineers reviewing the MAX1391ETB+ datasheet, MAX1391ETB+ pinout, MAX1391ETB+ application, or MAX1391ETB+ equivalent, this page provides verified technical context, validated pin functions, confirmed differential-input operation modes, and real-world design implications for battery-powered medical and industrial sensing systems.
Technical Context
The MAX1391ETB+ employs a track-and-hold circuit followed by an 8-bit SAR core, with conversion initiated on CS falling edge and sampling completed on the third SCLK falling edge. Its true-differential input accepts unipolar (0 to VREF) or bipolar (±VREF/2) signals, selected via the UNI/BIP pin, and supports common-mode range from 0 to VDD in bipolar mode.
It uses an external reference (0.6V to VDD), requires no internal reference, and outputs MSB-first serial data over 12 SCLK cycles - four leading zeros followed by eight data bits. Power-down occurs automatically after LSB clock-out (11th SCLK falling edge), achieving <1µA shutdown current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 8-bit SAR architecture with no missing codes over temperature |
| Throughput Rate | 416ksps maximum - enables real-time sampling of sub-200kHz signals |
| INL / DNL | ±0.2 LSB - ensures monotonicity and <0.1% full-scale linearity error |
| SINAD | 49dB at 100kHz - supports accurate digitization of medium-bandwidth sensor outputs |
| Supply Voltage | +1.5V to +3.6V - compatible with single LiMnO₂ coin cells or two alkaline/NiMH cells |
| Power @ 416ksps | 0.97mW at 1.8V - enables >10-year battery life in low-duty-cycle dataloggers |
| Reference Range | 0.6V to VDD - allows flexible scaling for varying signal amplitudes without external op-amps |
Pinout & Package
MAX1391ETB+ is housed in a 3mm × 3mm, 10-pin TDFN-EP package with exposed pad (not internally connected; recommended to tie to GND). The pinout supports true-differential analog input, unipolar/bipolar mode selection, and SPI-compatible serial communication.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | VDD | Positive supply input (1.5V–3.6V); requires local 0.1µF bypass to GND |
| 2 | AIN− | Negative differential analog input; referenced to AIN+ for bipolar/unipolar conversion |
| 3 | AIN+ | Positive differential analog input; forms true-differential pair with AIN− |
| 4 | GND | Analog/digital ground reference; star-point connection recommended |
| 5 | REF | External reference voltage input (0.6V–VDD+0.05V); bypassed with 0.1µF capacitor |
| 6 | UNI/BIP | Input mode select: high = unipolar (straight binary), low = bipolar (two's complement) |
| 7 | OE | Active-low output enable; drives DOUT high-impedance when high |
| 8 | CS | Active-low chip-select; falling edge initiates power-up, acquisition, and conversion sequence |
| 9 | DOUT | Serial data output; MSB-first, transitions on SCLK falling edge, high-Z when OE = high |
| 10 | SCLK | Serial clock input (0.1–5MHz); controls conversion timing and data clocking |
Key Features
| Feature | Design Value |
|---|---|
| True-differential analog input | Enables rejection of common-mode noise in sensor front-ends without external instrumentation amplifiers |
| Unipolar/bipolar mode selection | Single-pin configuration (UNI/BIP) eliminates firmware reconfiguration for AC-coupled or DC-coupled signal paths |
| AutoShutdown™ between conversions | Reduces average current to 3.1µW at 1ksps (1.8V), extending battery life in intermittent-sampling applications |
| SPI/QSPI/MICROWIRE/DSP compatibility | Interoperates with industry-standard microcontrollers and DSPs using standard 3-wire protocols without glue logic |
| Low-voltage operation (1.5V min) | Supports direct connection to aging alkaline/NiMH batteries or CR2032 coin cells without regulation |
Applications
| Portable Datalogging | Medical Instruments |
|---|---|
|
Use Scenario: Battery-powered environmental sensor node logging temperature, humidity, and pressure every 10 seconds. IC Role / Device Role / Timing Role: True-differential ADC digitizing bridge-based sensor outputs while rejecting PCB-level noise and supply ripple. Use Value: 0.97mW active power and <1µA shutdown current enable multi-year operation on two AA cells without voltage regulation. |
Use Scenario: Handheld ECG monitor acquiring lead-II differential biopotential signals at 250Hz with clinical-grade accuracy. IC Role / Device Role / Timing Role: Bipolar-mode ADC capturing ±1.25V ECG swing referenced to mid-supply, eliminating DC offset drift issues. Use Value: ±0.2 LSB INL and 49dB SINAD ensure diagnostic fidelity meets IEC 60601-2-27 requirements for portable ECG devices. |
| Battery-Powered Instruments | Process Control Sensors |
|
Use Scenario: Wireless pH/ORP meter used in field water quality testing with 20-hour runtime per charge. IC Role / Device Role / Timing Role: Low-noise differential front-end converting electrochemical cell voltage with programmable gain via external reference scaling. Use Value: 0.6V–VDD reference flexibility allows optimal SNR tuning across varying electrode output ranges without redesign. |
Use Scenario: Loop-powered 4–20mA transmitter monitoring tank level via differential pressure transducer in hazardous areas. IC Role / Device Role / Timing Role: High-EMI-tolerance ADC interfacing directly to isolated analog inputs in intrinsically safe designs. Use Value: Full-power bandwidth of 4MHz supports anti-alias filtering for 50/60Hz line rejection while maintaining fast step response. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-bit SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS7822U | 8-bit, 200ksps, single-ended only, 2.7–5.25V supply, internal reference | Lacks true-differential input and bipolar mode; requires higher supply voltage | Choose for cost-sensitive, single-ended, fixed-VREF systems where differential rejection is not required |
| MAX11100ETE+ | 12-bit, 500ksps, true-differential, 2.7–3.6V supply, integrated reference | Higher resolution and speed but incompatible low-voltage operation (no 1.5V support) | Choose when 12-bit precision and faster sampling are critical, and system can support ≥2.7V rails |
Compared with ADS7822U and MAX11100ETE+, the MAX1391ETB+ uniquely balances ultra-low-voltage operation (1.5V), true-differential input, and sub-1mW power at full speed - making it irreplaceable in coin-cell-powered, noise-sensitive, bipolar-signal applications.
Availability
MAX1391ETB+ is available at Aetrix Electronics and suitable for portable datalogging, battery-powered instruments, and medical sensing applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MAX1391ETB+ 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, medical, and portable applications.
The MAX1391ETB+ belongs to Maxim's micropower SAR ADC product line, engineered specifically for ultra-low-power, space-constrained, battery-operated systems demanding precision analog capture without voltage regulation.
FAQ
What is the input voltage range for MAX1391ETB+ in unipolar mode?
In unipolar mode (UNI/BIP = high), the MAX1391ETB+ accepts a true-differential input range of 0V to VREF across AIN+ and AIN−. With VREF set to 1.6V, this corresponds to 0V to 1.6V differential swing. The common-mode voltage must remain within 0V to VDD, and the device includes internal protection diodes allowing transient excursions to GND − 0.3V and VDD + 0.3V.
Does MAX1391ETB+ support bipolar input operation?
Yes, MAX1391ETB+ supports bipolar input operation when UNI/BIP is pulled low. In this mode, the true-differential input range becomes ±VREF/2 (e.g., ±0.8V for VREF = 1.6V), with output data in two's complement format. Common-mode voltage must stay between 0V and VDD, enabling robust AC-coupled sensor interfacing without external level-shifting circuitry.
What serial interface protocols does MAX1391ETB+ support?
MAX1391ETB+ supports SPI, QSPI, MICROWIRE, and generic DSP serial interfaces via its 3-wire (CS, SCLK, DOUT) architecture. It operates with CPOL = CPHA = 0 or 1, requires 12 SCLK cycles per conversion, and outputs 4 leading zeros followed by 8 MSB-first data bits. OE and CS may be tied together for simplified SPI/MICROWIRE use.
How does AutoShutdown™ work in MAX1391ETB+?
AutoShutdown™ in MAX1391ETB+ activates automatically after the LSB is clocked out on the 11th SCLK falling edge, reducing supply current to <1µA. This occurs regardless of CS or OE state unless OE is held high externally. Wake-up is triggered by the next CS falling edge, with 600ns acquisition time before conversion begins - optimizing energy use in burst-sampling systems.
Can MAX1391ETB+ operate from a single CR2032 lithium coin cell?
Yes, MAX1391ETB+ is explicitly designed for single CR2032 (LiMnO₂) operation: its 1.5V minimum supply voltage matches the flat discharge curve (~2.8V–2.0V), and its 3.1µW power draw at 1ksps (1.8V) enables multi-year runtime. No DC-DC converter is needed - VDD connects directly to the cell, with local 0.1µF bypassing to GND for stability.
MAX1391ETB+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Bulk
- Product Status:
- Active
- Number of Bits:
- 8
- Sampling Rate (Per Second):
- 416k
- Number of Inputs:
- 1
- Input Type:
- Differential
- Data Interface:
- SPI, DSP
- Configuration:
- MUX-S/H-ADC
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External
- Voltage - Supply, Analog:
- 1.5V ~ 3.6V
- Voltage - Supply, Digital:
- 1.5V ~ 3.6V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 10-TDFN (3x3)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
MAX1391ETB+ FAQ
1.How can I place an order for MAX1391ETB+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1391ETB+ 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 MAX1391ETB+ reliable?
The price and inventory of MAX1391ETB+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1391ETB+ is usually 5 days.
3.What payment methods are accepted for MAX1391ETB+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1391ETB+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1391ETB+?
MAX1391ETB+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1391ETB+ 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 MAX1391ETB+?
For technical support, including MAX1391ETB+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1391ETB+ requirements.
6.How does Aetrix verify that MAX1391ETB+ is sourced from the original manufacturer or authorized distributors?
All MAX1391ETB+ 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 MAX1391ETB+ meets industry standards.
7.What is the process for return or replacement of MAX1391ETB+?
All MAX1391ETB+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX1391ETB+, 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 MAX1391ETB+ part is unused and in its original packaging.
Return procedure for MAX1391ETB+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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