Analog Devices Inc./Maxim Integrated MAX1085BESA+

Overview

MAX1085BESA+ from Maxim Integrated is a 10-bit, 300ksps successive-approximation analog-to-digital converter (ADC) operating from a single +2.7V to +3.6V supply, featuring an internal +2.5V reference, SPI/QSPI/MICROWIRE-compatible 3-wire serial interface, and track/hold circuitry. It delivers ±1 LSB INL, ±1 LSB DNL, and 60dB SINAD at 75kHz input, targeting battery-powered instrumentation and portable data acquisition systems.

For engineers reviewing the MAX1085BESA+ datasheet, MAX1085BESA+ pinout, MAX1085BESA+ application, or MAX1085BESA+ equivalent, this page provides verified electrical parameters, thermal performance across –40°C to +85°C, timing constraints for 4.8MHz SCLK operation, and validated alternative options for low-power serial ADC selection.

Technical Context

The MAX1085BESA+ implements a SAR architecture with integrated track/hold and internal 2.5V reference, enabling unipolar 0–2.5V analog input conversion without external support components. Its serial interface requires only CS, SCLK, and DOUT, with MSB-first output format and 15-clock-cycle readout (3 leading zeros + 10 data bits + 2 sub-bits).

It operates in two modes: normal (2.5mA typical supply current at 300ksps) and shutdown (2µA typical), with wake-up time dependent on REF bypass capacitor discharge. Acquisition time is fixed at 625ns minimum, and aperture jitter is <50ps - critical for undersampling of signals up to 3MHz full-power bandwidth.

Key Specifications

Pinout & Package

MAX1085BESA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant and lead(Pb)-free. Pin functions are electrically validated per Maxim's official datasheet Rev 1 (12/10).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit serial ADC applications.

Compared with ADS7822U and MAX11105ETE+, the MAX1085BESA+ offers optimal trade-off of guaranteed monotonicity, integrated reference + T/H, 3-wire protocol flexibility, and compact 8-pin SO packaging - making it ideal for space-constrained, low-power, single-supply designs where 10-bit accuracy suffices.

Availability

MAX1085BESA+ is available at Aetrix Electronics and suitable for portable data logging, medical instrumentation, and battery-powered test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX1085BESA+ 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 communications applications.

The MAX1084/MAX1085 product line was designed for ultra-low-power, space-constrained data acquisition systems requiring integrated reference and serial interface simplicity - particularly in handheld and remote-sensor applications.

FAQ

What is the operating temperature range of the MAX1085BESA+?

The MAX1085BESA+ is specified for continuous operation from –40°C to +85°C. This extended industrial temperature range is validated across all key parameters including INL (±1 LSB), DNL (±1 LSB), VREF (2.48V–2.52V), and supply current (2.5mA typical at 300ksps). The device maintains monotonicity and no missing codes across this full range, as confirmed in the Electrical Characteristics table for MAX1085B variants.

Does the MAX1085BESA+ require external components for basic operation?

Yes - the MAX1085BESA+ requires a 4.7µF capacitor at the REF pin for stable internal reference operation, plus 0.1µF and 10µF bypass capacitors on VDD referenced to GND. These are mandatory per the datasheet's Typical Operating Circuit (Figure 3) and directly impact accuracy, wake-up time, and noise rejection. No external reference, op-amp, or track/hold circuit is needed.

What serial interface protocols does the MAX1085BESA+ support natively?

The MAX1085BESA+ supports SPI, QSPI, and MICROWIRE natively via its 3-wire interface (CS, SCLK, DOUT). It operates with CPOL = 0 and CPHA = 0 for SPI/MICROWIRE, and CPOL = 0 and CPHA = 1 for QSPI. No external logic or configuration registers are required - protocol selection is determined solely by host controller timing and clock phase settings.

How does shutdown mode affect the internal reference in the MAX1085BESA+?

In shutdown mode (SHDN = low), the internal 2.5V reference is disabled and the REF pin becomes high-impedance. The 4.7µF bypass capacitor discharges slowly, causing wake-up delay before accurate conversions can resume - up to 1.4ms after SHDN is deasserted if the capacitor was fully discharged. Reference re-stabilization time must be accounted for in low-duty-cycle sampling systems.

Is the MAX1085BESA+ pin-compatible with other devices in the MAX1084/MAX1085 family?

Yes - all MAX1084 and MAX1085 variants, including MAX1085BESA+, share identical 8-pin SO pinout and pin functions. This allows direct substitution between speed grades (e.g., MAX1085ACSA+ vs. MAX1085BESA+) and supply-voltage variants (e.g., MAX1084BCSA+ vs. MAX1085BESA+) without PCB changes, provided system-level voltage and timing constraints are met.