Analog Devices Inc./Maxim Integrated MAX187ACPA+

Overview

MAX187ACPA+ from Maxim Integrated is a 12-bit successive-approximation analog-to-digital converter (ADC) with integrated 4.096V buffered reference, single +5V supply operation, 75ksps throughput rate, ±½ LSB integral nonlinearity (A-grade), and 3-wire SPI/QSPI/MICROWIRE-compatible serial interface - used in portable data loggers and isolated sensor front-ends where low power and compact size are critical.

For engineers reviewing the MAX187ACPA+ datasheet, MAX187ACPA+ pinout, MAX187ACPA+ application, or MAX187ACPA+ equivalent, this page delivers verified technical context, exact pin functions for 8-pin PDIP, real-world AC/DC performance metrics, and two validated alternative ADCs for unipolar 0–4.096V signal digitization at ≤75ksps.

Technical Context

The MAX187ACPA+ implements an 8.5-clock-cycle SAR architecture with on-chip track/hold (1.5µs acquisition time), internal bandgap reference trimmed to 4.096V ±0.5%, and unipolar input range referenced to REF. It operates exclusively in normal or shutdown mode - SHDN pin controls both internal reference enable/disable and sub-10µA power-down state.

Its serial interface requires only CS, SCLK, and DOUT; conversion starts on CS falling edge, EOC is signaled by DOUT high, and 13 clock edges (MSB-first) shift out one leading '1' followed by 12 data bits. No external hold capacitor or clock generator is needed, and timing tolerates SCLK up to 5MHz with ≥100ns pulse width.

Key Specifications

Pinout & Package

MAX187ACPA+ is packaged in an 8-pin plastic dual in-line package (PDIP), pin-compatible with industry-standard through-hole prototyping and legacy industrial PCB layouts. Thermal performance supports continuous operation at TA = 0°C to +70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX187ACPA+, ADS7822U offers higher speed and supply flexibility but adds BOM cost and layout complexity for external reference, while TLV2541CD reduces system voltage and power at the expense of full-scale range and 5 V compatibility.

Availability

MAX187ACPA+ is available at Aetrix Electronics and suitable for portable data logging, remote DSP nodes, isolated industrial I/O modules, and high-accuracy process controllers requiring stable component supply across extended production lifecycles.

Supply support for MAX187ACPA+ 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 MAX187 series was developed specifically for low-power, space-constrained data acquisition systems needing integrated reference and simple 3-wire digital interfacing - targeting portable instrumentation and distributed sensor networks.

FAQ

What is the reference voltage accuracy and temperature stability of the MAX187ACPA+?

The MAX187ACPA+ features a laser-trimmed internal reference of 4.096 V with ±0.5% initial accuracy (±20.5 mV) at +25°C. Over the 0°C to +70°C operating range, its output remains within 4.060 V to 4.132 V (±0.88% FS), and its temperature coefficient is specified at ±30 ppm/°C for the 'C' grade. This stability ensures consistent LSB sizing (1 mV) without external calibration in most embedded applications.

How does the SHDN pin function on the MAX187ACPA+?

The SHDN pin on the MAX187ACPA+ is a three-level control: pulled low (≤0.5 V) places the device in shutdown mode drawing ≤10 µA; left floating disables the internal reference to allow external reference use; pulled high (≥VDD − 50 mV) enables the 4.096 V internal reference. This single pin simultaneously manages power state and reference selection - no additional logic or configuration registers are required.

Can the MAX187ACPA+ interface directly with an Arduino or STM32 microcontroller?

Yes, the MAX187ACPA+ interfaces directly with Arduino and STM32 MCUs using standard SPI hardware. Configure the MCU as master with CPOL = 0 and CPHA = 0; use any GPIO for CS; and clock at ≤2.5 MHz for guaranteed timing compliance. The MAX187ACPA+ outputs a leading '1' followed by 12 data bits on DOUT, requiring either 13-bit read routines or two 8-bit reads (first byte = 0x80 + top 7 bits, second = bottom 5 bits + 0x00).

What is the maximum allowable source impedance driving the AIN pin of the MAX187ACPA+?

The MAX187ACPA+ specifies a maximum source impedance of 5 kΩ for full AC performance (e.g., SINAD ≥70 dB). Its 16 pF input capacitance and 1.5 µs acquisition time mean higher impedances increase settling error and reduce effective resolution. For sources >5 kΩ, add an op-amp buffer (e.g., MAX427 or OP27) - the internal track/hold relaxes drive requirements compared to reference-free SAR ADCs, but does not eliminate them entirely.

Does the MAX187ACPA+ require external passive components for stable operation?

Yes, the MAX187ACPA+ requires two mandatory capacitors: a 4.7 µF tantalum or aluminum electrolytic capacitor between REF and GND (when internal reference is enabled), and a 0.1 µF ceramic capacitor between VDD and GND close to the package. These ensure reference stability and supply decoupling. Omitting the REF capacitor causes significant gain error and drift; omitting the VDD capacitor risks digital noise coupling into analog conversion results.