Analog Devices Inc./Maxim Integrated MAX1285BCSA+

Overview

MAX1285BCSA+ from Maxim Integrated is a 12-bit serial analog-to-digital converter (ADC) optimized for low-power, space-constrained systems operating from a single +2.7V to +3.6V supply. It integrates a track/hold amplifier, internal +2.5V reference (±15 ppm/°C tempco), SPI/QSPI/MICROWIRE-compatible 3-wire interface, and achieves 300ksps sampling rate with ±1 LSB INL/DNL accuracy - enabling high-fidelity signal digitization in battery-powered instrumentation and remote sensor nodes.

For engineers reviewing the MAX1285BCSA+ datasheet, MAX1285BCSA+ pinout, MAX1285BCSA+ application, or MAX1285BCSA+ equivalent, this page delivers verified electrical specs, validated SO-8 pin mapping, real-world use cases in medical and process control systems, and two confirmed alternative ADCs with documented functional trade-offs.

Technical Context

The MAX1285BCSA+ employs a successive-approximation register (SAR) architecture with an internal capacitive DAC and auto-zeroed comparator, supporting unipolar 0–2.5V input range referenced to its trimmed on-chip 2.5V reference. Conversion is initiated by CS falling edge and clocked by external SCLK up to 4.8MHz, with data output MSB-first on DOUT after three leading zeros.

Its track/hold acquisition time is 625ns (max), aperture jitter <50ps, and full-linear bandwidth of 250kHz ensures accurate digitization of signals up to ~250kHz without missing codes. Shutdown mode reduces supply current to 2µA (typ), and internal reference remains active only during conversion or normal operation - disabled when SHDN = GND.

Key Specifications

Pinout & Package

MAX1285BCSA+ 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 2 (12/10).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit serial ADC applications.

Compared with MAX1285BCSA+, ADS7822U trades speed and integration for higher precision and flexibility with external references, while AD7476ARTZ-REEL7 offers faster sampling but removes hardware shutdown control - making MAX1285BCSA+ optimal for ultra-low-power, self-contained 3.3V sensor nodes needing guaranteed monotonicity and minimal component count.

Availability

MAX1285BCSA+ is available at Aetrix Electronics and suitable for portable data logging, battery-powered instruments, and medical devices requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MAX1285BCSA+ 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 MAX1284/MAX1285 product line was designed specifically for low-power, single-supply, space-constrained data acquisition systems requiring integrated reference and serial interface - targeting portable instrumentation and remote sensing.

FAQ

What is the maximum sampling rate of the MAX1285BCSA+?

The MAX1285BCSA+ achieves a maximum sampling rate of 300ksps under specified conditions: VDD = +2.7V to +3.6V, fSCLK = 4.8MHz, and 16 clock cycles per conversion. This rate is fixed by the internal SAR timing and serial interface clock constraints - exceeding 4.8MHz SCLK violates timing specifications and risks data corruption. The MAX1285BCSA+ does not support programmable sample rates; it operates at full speed whenever CS is asserted and SCLK is active.

Does the MAX1285BCSA+ require an external reference voltage?

No, the MAX1285BCSA+ does not require an external reference voltage. It integrates a factory-trimmed +2.5V reference (2.48V to 2.52V over temperature) accessible at the REF pin. This internal reference drives both the ADC's conversion core and can serve as a precision voltage source for external circuitry, provided load current stays below 750µA. A minimum 4.7µF bypass capacitor is mandatory at REF for stability and accuracy.

Can the MAX1285BCSA+ interface directly with an SPI master microcontroller?

Yes, the MAX1285BCSA+ interfaces directly with standard SPI master peripherals configured for CPOL = 0 and CPHA = 0. Its 3-wire interface (SCLK, CS, DOUT) requires no level shifters when used with 3.3V-tolerant MCUs. Each conversion yields 12 data bits preceded by three leading zeros, transmitted MSB-first on DOUT synchronized to SCLK rising edges - matching standard SPI frame timing without additional protocol translation.

What is the purpose of the SHDN pin on the MAX1285BCSA+?

The SHDN (shutdown) pin on the MAX1285BCSA+ is an active-low control that reduces supply current from 2.5mA (active) to 2µA (typical) when pulled low. This feature enables aggressive power management in battery-operated systems. When exiting shutdown, the internal reference requires wake-up time dependent on the charge state of the 4.7µF REF bypass capacitor - up to 2ms after prolonged shutdown - during which conversions must be inhibited.

Is the MAX1285BCSA+ pin-compatible with the MAX1241?

Yes, the MAX1285BCSA+ is explicitly documented as pin-compatible with the MAX1241 and serves as a higher-speed upgrade. Both share identical 8-pin SO packaging and pin assignments (VDD, AIN, SHDN, REF, GND, DOUT, CS, SCLK). However, the MAX1285BCSA+ operates at 300ksps versus the MAX1241's 114ksps and uses a lower 2.7–3.6V supply - meaning direct replacement is feasible only if the host system's supply rail and timing budget accommodate these differences.