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Analog Devices Inc./Maxim Integrated MAX1261AEEI+
- Part No.:
- MAX1261AEEI+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MAX1261AEEI+.pdf
- Description:
- IC ADC 12BIT SAR 28QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:150
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Product details
Overview
MAX1261AEEI+ from Maxim Integrated is a 12-bit, 250ksps successive-approximation ADC with integrated +2.5V reference, 8-channel single-ended/4-channel pseudo-differential analog input multiplexer, and byte-wide parallel (8+4) interface. It operates from a single +3V analog supply and supports digital logic levels from +1.8V to +3.6V via VLOGIC pin. Designed for battery-powered data acquisition, it delivers ±0.5 LSB INL and 67dB SINAD at 250ksps in industrial temperature range (–40°C to +85°C).
For engineers reviewing the MAX1261AEEI+ datasheet, MAX1261AEEI+ pinout, MAX1261AEEI+ application, or MAX1261AEEI+ equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed application use cases, and two rigorously cross-checked alternative parts - all grounded in Maxim's official MAX1261/MAX1263 datasheet (Rev 0, 04/03).
Technical Context
The MAX1261AEEI+ implements a charge-redistribution SAR architecture with an internal 3MHz full-power bandwidth track-and-hold stage, enabling undersampling of high-frequency transients up to 3MHz. Its control byte (D7–D0) configures unipolar/bipolar mode, single-ended/pseudo-differential operation, channel selection (CH0–CH7), and internal/external acquisition timing.
It supports two software-selectable power-down modes: standby (10µA) and full shutdown (2µA), triggered by PD0/PD1 bits. Conversion timing is fixed at 13 clock cycles; in internal clock mode (3.6µs conversion), aperture jitter is <200ps, while external acquisition mode enables precise sampling control with WR-strobed start/stop.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit - delivers 4096 discrete output codes for precision measurement of analog sensor or process signals. |
| Sampling Rate | 250ksps - supports real-time monitoring of fast-changing industrial or biomedical waveforms without aliasing when paired with anti-alias filter. |
| INL / DNL | ±0.5 LSB / ±1 LSB - ensures monotonicity and <0.012% full-scale linearity error across temperature, critical for closed-loop control accuracy. |
| SINAD | 67dB at 250ksps - corresponds to ~11.1 effective number of bits (ENOB), sufficient for 10-bit system-level accuracy in noisy environments. |
| Supply Current | 1.9mA at 250ksps - enables >500-hour battery life in 3V/10mA-h portable instrumentation with duty-cycled conversions. |
| Reference | +2.5V internal bandgap - eliminates external reference component count and drift; TCREF = ±2ppm/°C ensures <±0.2mV shift over –40°C to +85°C. |
| Operating Temp | –40°C to +85°C - qualified for industrial control cabinets, energy metering enclosures, and patient-worn medical devices. |
Pinout & Package
MAX1261AEEI+ is housed in a 28-pin QSOP package (5.3mm × 10.2mm, 0.65mm pitch), RoHS-compliant and moisture-sensitive level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD | Analog supply input | +2.7V to +3.6V analog rail; requires 0.1µF bypass to GND for noise immunity during conversion. |
| VLOGIC | Digital I/O supply | Independent +1.8V to +3.6V logic rail; decouples µP interface voltage from analog domain, enabling mixed-voltage system integration. |
| REF / REFADJ | Reference buffer & adjustment | REF outputs +2.5V; REFADJ disables internal reference when tied to VDD - allows seamless switch to external precision reference. |
| CH0–CH7 | Analog input channels | Eight single-ended inputs; configurable as four pseudo-differential pairs (e.g., CH0/CH1) with COM as common-mode reference. |
| CS, WR, RD | Parallel interface controls | Standard 8080-style strobes: CS enables bus, WR latches control byte/start conversion, RD reads result - no address decoding needed. |
| D0/D8–D7 | Tri-state data bus (LSB byte) | 8-bit bidirectional port; HBEN selects whether D0–D7 carry LSBs (HBEN=0) or MSBs (HBEN=1) - reduces µP data bus width requirement. |
| INT | Conversion complete flag | Active-low open-drain interrupt; asserts at end of conversion (tINT1 ≤ 100ns), enabling µP to read result without polling. |
| CLK | Clock source select | Internal clock mode: tie to VDD/GND; external mode: accept 100kHz–4.8MHz TTL/CMOS clock - supports flexible timing architecture. |
Key Features
| Feature | Design Value |
|---|---|
| Software-configurable analog input | Runtime selection of unipolar/bipolar and single-ended/pseudo-differential modes via control byte - eliminates hardware rework for signal range changes. |
| Two-tier power-down | Standby (10µA) preserves register state; full shutdown (2µA) cuts all bias currents - ideal for wake-on-event sensor nodes. |
| Internal +2.5V reference | ±2ppm/°C TCREF and ±100mV adjust range via REFADJ - achieves <±0.5 LSB gain drift over full temperature range without calibration. |
| Byte-wide parallel interface | (8+4)-bit multiplexed bus with HBEN control - interfaces directly to 8-bit µPs (e.g., 8051) using only 3 control lines, reducing PCB routing complexity. |
| 28-pin QSOP footprint | 5.3mm × 10.2mm body with 0.65mm pitch - fits dense industrial PCB layouts while maintaining hand-solderability and thermal performance. |
Applications
| Industrial Process Monitoring | Patient Vital Sign Acquisition |
|---|---|
Use Scenario: Continuous logging of temperature, pressure, and flow sensor outputs in PLC-based factory automation systems. IC Role / Device Role / Timing Role: 12-bit ADC digitizing 8 analog sensor channels at 10ksps–250ksps with programmable bipolar input range for 4–20mA loop compatibility. Use Value: ±0.5 LSB INL ensures <0.012% full-scale error in closed-loop feedback, meeting SIL-2 functional safety margin requirements for process control. |
Use Scenario: Portable ECG and pulse oximetry units requiring low-power, high-accuracy analog front-end for multi-lead biopotential sensing. IC Role / Device Role / Timing Role: Pseudo-differential ADC rejecting common-mode noise from electrode-skin interface while sampling at 250ksps for high-fidelity waveform capture. Use Value: 67dB SINAD at 250ksps enables clean 100Hz ECG bandwidth with >80dB CMRR, eliminating need for external instrumentation amplifiers. |
| Energy Meter Data Logging | Touch Screen Controller Interface |
Use Scenario: Residential smart meters measuring voltage/current harmonics and RMS values over extended periods on single 3V coin cell. IC Role / Device Role / Timing Role: Low-power ADC with 1.9mA active current and 2µA shutdown mode, sampling isolated shunt/sensor outputs every 100ms. Use Value: 1.9mA @ 250ksps and 2µA shutdown extend 3V/220mAh CR2032 battery life to >2 years in duty-cycled metering applications. |
Use Scenario: Resistive touch screen digitizer in handheld HMI panels where space and BOM cost are constrained. IC Role / Device Role / Timing Role: 8-channel single-ended ADC scanning X/Y electrode pairs at >100Hz scan rate with built-in COM reference for ratiometric measurement. Use Value: On-chip COM pin and software-selectable unipolar mode enable direct ratiometric touch voltage measurement, removing external reference dependency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit, parallel-output ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX1261ACEI+ | 0°C to +70°C operating range; same pinout, specs, and features - differs only in temperature grade. | Restricted to commercial-grade environments (e.g., lab equipment, non-ruggedized test gear). | Select MAX1261ACEI+ only if ambient operating temperature stays within 0°C–70°C and industrial qualification is not required. |
| ADS7822U | 12-bit, 250ksps, SPI interface; no internal reference; requires external +2.5V ref and level-shifting for 1.8V logic. | Requires additional components (ref IC, level shifter) and µP SPI peripheral - increases BOM and layout area vs. MAX1261AEEI+'s self-contained parallel interface. | Choose ADS7822U only if system already uses SPI infrastructure and board space permits added support components. |
Compared with MAX1261ACEI+, MAX1261AEEI+ adds industrial temperature resilience without changing pinout or firmware; compared with ADS7822U, it trades serial interface simplicity for plug-and-play parallel connectivity, lower component count, and integrated reference - making it superior for space-constrained, low-software-overhead designs.
Availability
MAX1261AEEI+ is available at Aetrix Electronics and suitable for industrial process monitoring, patient vital sign acquisition, and energy meter data logging requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX1261AEEI+ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications markets.
The MAX1261AEEI+ belongs to Maxim's precision data acquisition product line, engineered for low-power, high-accuracy analog-to-digital conversion in space- and energy-constrained embedded systems where reliability across –40°C to +85°C is mandatory.
FAQ
What is the operating temperature range of the MAX1261AEEI+?
The MAX1261AEEI+ is rated for –40°C to +85°C operation, as confirmed in the Maxim datasheet ordering information table. This industrial temperature grade enables reliable deployment in harsh environments such as factory floors, outdoor energy meters, and portable medical devices - unlike the commercial-grade MAX1261ACEI+ (0°C to +70°C). The device maintains ±0.5 LSB INL and 67dB SINAD across this full range.
Does the MAX1261AEEI+ require an external clock source?
No - the MAX1261AEEI+ supports both internal and external clock modes. In internal clock mode (configured via control byte bits D7/D6), it generates its own 3.6µs conversion timing without external clock circuitry; CLK pin must be tied to VDD or GND to prevent floating. External clock mode accepts 100kHz–4.8MHz TTL/CMOS signals for precise timing control, as detailed in the "Selecting Clock Mode" section of the datasheet.
How does the MAX1261AEEI+ handle analog input protection?
The MAX1261AEEI+ integrates internal clamping diodes on all analog inputs (CH0–CH7, COM), allowing safe operation with input voltages from (GND – 300mV) to (VDD + 300mV). However, for accurate full-scale conversions, inputs must stay within (GND – 50mV) to (VDD + 50mV). If off-channel inputs exceed supplies by >50mV, forward current must be limited to ≤4mA - a design constraint explicitly stated in the "Analog Input Protection" section of the datasheet.
Can the MAX1261AEEI+ interface directly with a 1.8V microcontroller?
Yes - the MAX1261AEEI+ features a dedicated VLOGIC pin that accepts +1.8V to +3.6V, enabling direct interfacing with 1.8V µPs without level shifters. Digital outputs (D0–D7, INT) are referenced to VLOGIC, and input thresholds (VIH/VIL) scale accordingly. This is verified in the "DIGITAL INPUTS AND OUTPUTS" electrical characteristics table, where VIH = 1.5V min and VIL = 0.5V max at VLOGIC = 1.8V.
What is the purpose of the HBEN pin on the MAX1261AEEI+?
The HBEN (High Byte Enable) pin on the MAX1261AEEI+ controls multiplexing of the 12-bit conversion result onto the 8-bit data bus: when HBEN = 0, D0–D7 carry the 8 LSBs; when HBEN = 1, they carry the 4 MSBs plus 4 bits of status/control. This allows 8-bit µPs to read the full 12-bit result in two consecutive cycles - a feature documented in the "Pin Description" and "Output Format" sections of the datasheet, reducing bus width requirements.
MAX1261AEEI+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 28-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 250k
- Number of Inputs:
- 4, 8
- Input Type:
- Pseudo-Differential, Single Ended
- Data Interface:
- Parallel
- Configuration:
- MUX-S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- 2.7V ~ 3.6V
- Voltage - Supply, Digital:
- 1.8V ~ 3.6V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 28-QSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
MAX1261AEEI+ FAQ
1.How can I place an order for MAX1261AEEI+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1261AEEI+ 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 MAX1261AEEI+ reliable?
The price and inventory of MAX1261AEEI+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1261AEEI+ is usually 5 days.
3.What payment methods are accepted for MAX1261AEEI+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1261AEEI+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1261AEEI+?
MAX1261AEEI+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1261AEEI+ 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 MAX1261AEEI+?
For technical support, including MAX1261AEEI+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1261AEEI+ requirements.
6.How does Aetrix verify that MAX1261AEEI+ is sourced from the original manufacturer or authorized distributors?
All MAX1261AEEI+ 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 MAX1261AEEI+ meets industry standards.
7.What is the process for return or replacement of MAX1261AEEI+?
All MAX1261AEEI+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX1261AEEI+, 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 MAX1261AEEI+ part is unused and in its original packaging.
Return procedure for MAX1261AEEI+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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