Analog Devices Inc./Maxim Integrated MAX1243BCPA+

Overview

MAX1243BCPA+ 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 draw.

For engineers reviewing the MAX1243BCPA+ datasheet, MAX1243BCPA+ pinout, MAX1243BCPA+ application, or MAX1243BCPA+ equivalent, this page delivers verified technical context, real-world design meaning for key specs, validated pin functions, confirmed alternative options, and supply-chain support details specific to the MAX1243BCPA+ in 8-pin PDIP package.

Technical Context

The MAX1243BCPA+ implements a track/hold circuit with 1.5µs acquisition time and a 10-bit SAR core clocked by an internal oscillator, eliminating need for external conversion timing control. Its 3-wire serial interface uses unipolar MSB-first output with EOC signaling via DOUT high transition, supporting direct connection to standard microcontroller I/O ports without level-shifting.

Unlike the MAX1242 variant, the MAX1243BCPA+ requires an external reference voltage (1.0V to VDD), accepts inputs from 0V to VREF, and exhibits ±1 LSB integral nonlinearity over 0°C to +70°C. It achieves 66dB SINAD and 70dB SFDR at 10kHz input while consuming only 3mW at 73ksps (VDD = 3V).

Key Specifications

Pinout & Package

MAX1243BCPA+ is housed in an 8-pin plastic dual in-line package (PDIP) with through-hole mounting and RoHS-compliant lead finish. Pin spacing is 0.300", body width 0.360", and total length 0.925". Thermal resistance θ_JA is 9.09mW/°C above +70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1243BCSA+, the MAX1243BCPA+ offers identical performance in a through-hole package enabling manual assembly and socket-based validation; versus ADS7822U, it trades speed for external reference control and 40% lower active power-critical for energy harvesting and long-life battery systems.

Availability

MAX1243BCPA+ is available at Aetrix Electronics and suitable for portable data logging, process control monitoring, and test equipment requiring stable component supply across industrial temperature grades and long production lifecycles.

Supply support for MAX1243BCPA+ 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 precision analog, mixed-signal, and high-reliability ICs for industrial, medical, and communications systems.

The MAX1242/MAX1243 product line was designed for low-power, space-constrained data acquisition where external reference flexibility, small footprint, and micropower shutdown are essential-targeting sensor interfaces in portable and remote instrumentation.

FAQ

What is the reference voltage requirement for MAX1243BCPA+?

The MAX1243BCPA+ 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 external reference must provide ≤10Ω output impedance and sustain up to 250µA load current during conversion. A minimum 0.1µF ceramic capacitor is required at REF for stability, with larger values (e.g., 4.7µF) recommended for noisy references. This design allows ratiometric measurements and system-level reference sharing not possible with internal-reference-only ADCs like the MAX1242.

How does the MAX1243BCPA+ enter and exit shutdown mode?

The MAX1243BCPA+ enters shutdown mode when the SHDN pin is pulled low, reducing supply current to <15µA. It exits shutdown when SHDN is driven high or left open (floating), returning to full operation. Unlike the MAX1242, SHDN high does not enable an internal reference on the MAX1243BCPA+-it solely controls power state. Wake-up time is approximately 4µs if the external reference remains powered; if the reference is also shut down, wake-up depends on that reference's power-up characteristics. No special initialization sequence is needed beyond ensuring stable VDD and REF before the first CS assertion.

What are the timing requirements for reading conversion results from MAX1243BCPA+?

After initiating a conversion with a CS falling edge, the MAX1243BCPA+ completes conversion in 7.5µs (max). The end-of-conversion (EOC) is signaled by DOUT rising. Data is then clocked out on SCLK falling edges, MSB first. At least 13 falling clock edges are required to read the full 10-bit result plus leading EOC bit and two sub-bits. SCLK frequency may run up to 2.1MHz, with each phase ≥200ns. DOUT remains valid for tDV (240ns min) after SCLK fall. Pulling CS high during readback halts further data output, and tCS (240ns min) must elapse before the next CS assertion.

Can MAX1243BCPA+ interface directly with an SPI master without level shifting?

Yes, the MAX1243BCPA+ interfaces directly with standard 3.3V or 5V SPI masters. Its digital inputs (CS, SCLK, SHDN) accept VIH ≥2.0V (VDD ≤3.6V) or ≥VDD −0.4V (VDD >3.6V), and VIL ≤0.8V-fully compatible with CMOS logic levels. DOUT outputs VOH ≥VDD −0.5V and VOL ≤0.4V, meeting SPI output thresholds. No level shifters are needed when VDD matches the host µC's I/O voltage. The interface operates with CPOL = 0 and CPHA = 0, matching standard SPI Mode 0 timing, and supports QSPI and MICROWIRE protocols without modification.

What is the maximum source impedance allowed at the AIN pin of MAX1243BCPA+?

The MAX1243BCPA+ analog input has 16pF capacitance and a 9kΩ input resistance. For accurate acquisition within the specified 1.5µs minimum time, source impedance (RS) should be ≤4kΩ. Higher impedances increase acquisition time per tACQ = 7(RS + 9kΩ) × 16pF and degrade AC performance. If RS exceeds 4kΩ, a 0.01µF capacitor placed directly at AIN forms an RC filter that limits bandwidth but stabilizes sampling. However, this filter must be accounted for in system anti-aliasing design, and the reference must still meet 10Ω output impedance and 250µA drive capability to maintain DC accuracy.