Analog Devices Inc./Maxim Integrated MAX1243ACSA+

Overview

MAX1243ACSA+ from Maxim Integrated is a low-power, 10-bit successive-approximation analog-to-digital converter (ADC) operating from +2.7V to +5.25V supply, featuring 73ksps throughput, 7.5µs conversion time, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface. It requires an external reference voltage (1.0V to VDD), supports 0V to VREF input range, and targets space-constrained, battery-powered data acquisition systems.

For engineers reviewing the MAX1243ACSA+ datasheet, MAX1243ACSA+ pinout, MAX1243ACSA+ application, or MAX1243ACSA+ equivalent, this page delivers verified technical context, SO-8 package mapping, real-world timing behavior, confirmed AC/DC accuracy specs, and validated alternative options for sensor interface design.

Technical Context

The MAX1243ACSA+ implements a track/hold circuit with 1.5µs acquisition time and a 10-bit SAR core clocked internally-no external clock required for conversion completion. Its 3-wire serial interface uses unipolar MSB-first output format with EOC signaling via DOUT high transition.

It operates in two modes: normal (3mW at 73ksps, VDD = 3V) and shutdown (2µA typical), with SHDN pin enabling three-level control (low = shutdown, high/open = active). The REF pin accepts external references from 1.0V to VDD, with specified load regulation of 0.35mV over 0–0.2mA output current.

Key Specifications

Pinout & Package

MAX1243ACSA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant, with gull-wing leads and standard JEDEC MO-153 footprint (S8+5, outline 21-0041).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1243ACSA+, MAX1242ACSA+ simplifies BOM by integrating the reference but sacrifices reference flexibility, while ADS7822U trades guaranteed acquisition performance for raw speed-neither offers pin compatibility or identical functional scope.

Availability

MAX1243ACSA+ is available at Aetrix Electronics and suitable for portable data logging, process control monitoring, and test equipment requiring stable component supply, long-term manufacturability, and RoHS-compliant sourcing.

Supply support for MAX1243ACSA+ 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 MAX1242/MAX1243 family was engineered for ultra-low-power, space-constrained sensor interfacing-emphasizing integrated track/hold, minimal external components, and seamless µC connectivity via industry-standard serial protocols.

FAQ

What is the reference voltage requirement for MAX1243ACSA+?

The MAX1243ACSA+ requires an external reference voltage applied to the REF pin, ranging from 1.0V to VDD. It does not include an internal reference. For optimal accuracy, the reference must provide ≤10Ω output impedance and sustain up to 250µA load current during conversion; a minimum 0.1µF ceramic capacitor is required for bypassing. The MAX1243ACSA+ achieves ±0.5 LSB INL when used with a stable 2.5V reference.

Does MAX1243ACSA+ support SPI interface timing without modification?

Yes, MAX1243ACSA+ natively supports SPI interface timing with CPOL = 0 and CPHA = 0. Its 3-wire serial interface is fully compatible with standard SPI peripherals-DOUT acts as MISO, CS as SS, and SCLK as SCK. The device outputs MSB-first with EOC signaled by DOUT high transition, and tolerates SCLK frequencies up to 2.1MHz. No level-shifting or protocol translation is needed for direct connection to common microcontrollers.

What is the maximum source impedance allowed for the AIN pin of MAX1243ACSA+?

The MAX1243ACSA+ AIN pin has 16pF input capacitance and 9kΩ input resistance. With source impedance ≤4kΩ, AC performance remains unaffected. For higher impedances, acquisition time increases per tACQ = 7(RS + RIN) × 16pF, with minimum tACQ = 1.5µs. To maintain accuracy with RS > 4kΩ, add a 0.01µF capacitor at AIN to form an RC filter-though this limits input signal bandwidth accordingly.

How does shutdown mode function on MAX1243ACSA+?

Shutdown mode on MAX1243ACSA+ is activated by pulling the SHDN pin low, reducing supply current to 2µA typical (VDD ≤ 3.6V). The device wakes up in ~4µs if the external reference remains powered; full accuracy resumes after tWAKE. In shutdown, the internal track/hold and SAR are disabled, DOUT goes high-impedance, and CS/SCLK inputs are ignored. SHDN left open or pulled high maintains normal operation-no internal reference is enabled in MAX1243ACSA+.

Can MAX1243ACSA+ be used with a 1.8V microcontroller I/O interface?

MAX1243ACSA+ digital I/O pins (CS, SCLK, DOUT) are CMOS-compatible with VIH = 2.0V (min) and VIL = 0.8V (max) at VDD ≤ 3.6V, making direct interface to 1.8V µCs unsafe without level translation. When VDD = 3.3V, DOUT VOH ≈ 2.8V and VOL ≈ 0.4V-exceeding 1.8V µC input thresholds. Use bidirectional level translators (e.g., TXB0104) or ensure µC GPIOs tolerate 3.3V inputs before connecting to MAX1243ACSA+.