Analog Devices Inc./Maxim Integrated MAX1243BEPA+

Overview

MAX1243BEPA+ from Maxim Integrated is a low-power, 10-bit successive-approximation analog-to-digital converter (ADC) with external reference input, 73ksps throughput, 7.5µs conversion time, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface. It operates from a single +2.7V to +5.25V supply and targets space-constrained, battery-powered data acquisition systems requiring precision and minimal power.

For engineers reviewing the MAX1243BEPA+ datasheet, MAX1243BEPA+ pinout, MAX1243BEPA+ application, or MAX1243BEPA+ equivalent, this page delivers verified technical context, real-world design meaning for key specs, validated SO-8 pin functions, confirmed alternatives with documented differences, and application-specific implementation guidance - all grounded in Maxim's official Rev 3 datasheet.

Technical Context

The MAX1243BEPA+ implements a track/hold circuit with 1.5µs acquisition time and a 10-bit SAR core clocked internally, eliminating need for external conversion timing control. Its 3-wire serial interface uses unipolar MSB-first format with EOC signaling via DOUT high transition, supporting up to 2.1MHz SCLK with unrestricted duty cycle (≥200ns per phase).

Unlike the MAX1242 variant, the MAX1243BEPA+ requires an external reference voltage (1.0V to VDD), accepts 0V to VREF analog inputs, and draws only 3mW at 73ksps (VDD = 3V). Shutdown mode reduces supply current to ≤2µA, with wake-up time dependent on external reference stability rather than internal capacitor recharge.

Key Specifications

Pinout & Package

MAX1243BEPA+ is housed in an 8-pin plastic DIP (PDIP) package with gull-wing leads, RoHS-compliant and lead-free (+ suffix), rated for -40°C to +85°C operation. Pin 1 is bottom-left corner when notch faces up; pin numbering follows standard DIP convention (counter-clockwise).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1243BCSA+, the MAX1243BEPA+ offers identical electrical performance in a through-hole package suited for prototyping and high-reliability industrial environments; versus ADS7822U, it trades resolution for configurability, enabling ratiometric sensing and ultra-low-power sleep modes critical in remote monitoring.

Availability

MAX1243BEPA+ is available at Aetrix Electronics and suitable for portable instrumentation, industrial process controllers, and isolated medical data acquisition requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX1243BEPA+ 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, automotive, and communications markets.

The MAX1242/MAX1243 family was designed specifically for low-power, space-constrained data acquisition systems needing precision ADCs with flexible reference architecture and minimal external components - targeting battery-operated sensors and distributed I/O modules.

FAQ

What is the maximum external reference voltage supported by the MAX1243BEPA+?

The MAX1243BEPA+ accepts external reference voltages from 1.0V up to the positive supply voltage (VDD), which itself ranges from +2.7V to +5.25V. For guaranteed accuracy, the reference must maintain ≤10Ω output impedance and supply up to 250µA during conversion. Using a reference above 2.5V expands full-scale input range but does not increase resolution - 1 LSB remains VREF/1024.

Does the MAX1243BEPA+ require an external clock to perform conversion?

No, the MAX1243BEPA+ does not require an external clock to perform the analog-to-digital conversion - its internal successive-approximation circuitry runs autonomously once initiated by a CS falling edge. The external SCLK is used solely for reading out the 10-bit result and two sub-bits via the serial interface, and can be applied at any time after conversion completion (signaled by DOUT rising edge).

How does the SHDN pin function on the MAX1243BEPA+?

On the MAX1243BEPA+, the SHDN pin operates as a three-state shutdown control: pulling it low reduces supply current to ≤2µA; leaving it open or driving it high enables normal operation. Unlike the MAX1242, the SHDN pin has no effect on internal reference activation - the MAX1243BEPA+ always requires an external reference regardless of SHDN state.

What is the purpose of the leading '1' bit and two sub-bits in the MAX1243BEPA+ serial output stream?

The MAX1243BEPA+ serial output begins with a leading '1' bit indicating end-of-conversion (EOC), followed by 10 data bits (MSB first), then two sub-bits (S1, S0) used for internal diagnostics and gain calibration, and trailing zeros if additional clocks are applied. This 13-bit structure allows µC firmware to detect conversion completion unambiguously and supports advanced calibration routines without requiring separate status polling.

Can the MAX1243BEPA+ be used with a microcontroller that only supports standard SPI mode 0 (CPOL=0, CPHA=0)?

Yes, the MAX1243BEPA+ is fully compatible with SPI mode 0 (CPOL=0, CPHA=0). Its DOUT transitions on the falling edge of SCLK and is sampled on the rising edge - matching standard SPI master behavior. Conversion starts on CS falling edge; DOUT goes low during conversion and rises to signal completion, enabling synchronous readout with two 8-bit transfers to capture all 10+2 bits.