Analog Devices Inc./Maxim Integrated MAX1243ACPA+

Overview

MAX1243ACPA+ from Maxim Integrated is a low-power, 10-bit successive-approximation analog-to-digital converter (SAR ADC) with external reference input, single +2.7V to +5.25V supply operation, 73ksps throughput, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface. It features an internal track/hold (1.5µs acquisition), 7.5µs conversion time, ±0.5 LSB INL, and operates in 0°C to +70°C industrial temperature range in 8-pin PDIP package - ideal for portable data loggers and isolated sensor interfaces where precision, low power, and compact footprint are critical.

For engineers reviewing the MAX1243ACPA+ datasheet, MAX1243ACPA+ pinout, MAX1243ACPA+ application, or MAX1243ACPA+ equivalent, this page delivers verified technical context, exact pin functions, real-world use cases, and validated alternative options - all grounded in Maxim's official Rev 3 (Jan 2012) datasheet and ordering information.

Technical Context

The MAX1243ACPA+ implements a capacitive SAR architecture with integrated track/hold, requiring no external clock for conversion completion - only for serial data readout. Its REF pin accepts external reference voltages from 1.0V to VDD, with specified accuracy maintained up to 250µA load current and ≤10Ω source impedance.

Conversion is initiated by CS falling edge; DOUT signals end-of-conversion (EOC) with a rising edge, then outputs 10-bit unipolar data (MSB-first) plus two sub-bits and leading EOC bit over the 3-wire interface. Shutdown mode reduces supply current to ≤2µA (typical), with wake-up time dependent on external reference stability rather than internal circuitry.

Key Specifications

Pinout & Package

MAX1243ACPA+ is housed in an 8-pin plastic dual-inline package (PDIP), RoHS-compliant (indicated by '+' suffix), with GND-connected substrate and BiCMOS process technology.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1243ACPA+, the MAX1243ACSA+ offers identical performance in a smaller SO package but requires SMT assembly, while ADS7822U provides faster sampling at the cost of increased power and loss of hardware shutdown control - making MAX1243ACPA+ optimal for low-power, through-hole, industrial-grade designs.

Availability

MAX1243ACPA+ is available at Aetrix Electronics and suitable for portable data logging, process control monitoring, and temperature measurement applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MAX1243ACPA+ 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, automotive, and communications markets.

The MAX1242/MAX1243 product line was designed for low-power, space-constrained data acquisition systems requiring precision, simplicity, and robust serial interfacing - targeting remote sensors, handheld instruments, and distributed control nodes.

FAQ

What is the reference voltage requirement for MAX1243ACPA+?

The MAX1243ACPA+ requires an external reference voltage applied to the REF pin, ranging from 1.0V to VDD. For optimal accuracy, the reference must deliver up to 250µA load current with ≤10Ω output impedance and be bypassed with ≥0.1µF capacitor. Unlike the MAX1242, it has no internal reference - so MAX1243ACPA+ cannot operate without an external reference source.

Does MAX1243ACPA+ support SPI mode with CPOL=0 and CPHA=0?

Yes, MAX1243ACPA+ is fully compatible with SPI, QSPI, and MICROWIRE protocols using CPOL=0 and CPHA=0. The device outputs data on DOUT at SCLK's falling edge and expects clock edges to be stable before and after transitions. Two-byte reads (first byte: EOC + 7 MSBs; second byte: 3 LSBs + 2 sub-bits) recover the full 10-bit result as specified in Maxim's Figure 12 timing diagram.

What is the maximum source impedance allowed at AIN for accurate operation of MAX1243ACPA+?

For minimal impact on AC performance, the analog input source impedance should be ≤4kΩ. Higher impedances increase acquisition time (tACQ = 7 × (RS + RIN) × 16pF) and may degrade THD/SINAD; if RS exceeds 4kΩ, a 0.01µF capacitor at AIN is recommended to form an RC filter - though this limits input signal bandwidth accordingly.

How does shutdown mode work on MAX1243ACPA+?

Driving SHDN low places MAX1243ACPA+ into shutdown mode, reducing supply current to ≤2µA. Unlike the MAX1242, SHDN state does not affect reference configuration - MAX1243ACPA+ always uses external reference regardless of SHDN level. Wake-up time depends solely on external reference stability and is typically ~4µs if the reference remains powered.

Can MAX1243ACPA+ be used with a 3.3V microcontroller without level shifting?

Yes, MAX1243ACPA+ is fully compatible with 3.3V microcontrollers: its digital inputs (CS, SCLK, SHDN) accept VIH ≥2.0V and VIL ≤0.8V at VDD ≤3.6V, and DOUT outputs VOH ≥VDD − 0.5V and VOL ≤0.4V - satisfying 3.3V logic thresholds directly. No level-shifting circuitry is needed for interfacing with standard 3.3V MCUs.