Analog Devices Inc./Maxim Integrated MAX189ACPA+

Overview

MAX189ACPA+ from Maxim Integrated is a 12-bit successive-approximation analog-to-digital converter (ADC) operating from a single +5V supply, accepting 0–5V unipolar analog input with internal track/hold and 75ksps throughput. It requires an external reference voltage (2.5V to VDD), features SPI/QSPI/MICROWIRE-compatible 3-wire serial interface, and delivers ±½ LSB integral nonlinearity at 25°C in 8-pin PDIP package - ideal for isolated data acquisition and remote sensor digitization.

For engineers reviewing the MAX189ACPA+ datasheet, MAX189ACPA+ pinout, MAX189ACPA+ application, or MAX189ACPA+ equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative parts with functional distinctions, and supply-chain support details specific to industrial embedded and low-power measurement systems.

Technical Context

The MAX189ACPA+ implements a 12-bit SAR architecture with integrated track/hold circuitry acquiring signals in ≤1.5µs, enabling accurate sampling of transients up to 4.5MHz small-signal bandwidth. Its conversion cycle completes in 8.5 clock periods (t_CONV), synchronized to an external SCLK up to 5MHz.

It operates exclusively in unipolar mode with full-scale range defined by externally applied V_REF (2.5V to VDD); no internal reference is present. Digital interface uses CS-active-low initiation, DOUT MSB-first output on SCLK falling edge, and supports 13-cycle readout including leading EOC bit - fully compatible with SPI (CPOL=0, CPHA=0) and QSPI protocols.

Key Specifications

Pinout & Package

MAX189ACPA+ is housed in an 8-pin plastic dual-inline package (PDIP) with 0.3-inch body width and through-hole mounting. Pin functions are electrically validated per Maxim's official pin description table and functional diagram.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7816U and AD7893AN-10, MAX189ACPA+ uniquely balances low power (1.5mA), external reference flexibility, and compact 8-pin PDIP packaging - making it optimal for space-constrained, battery-operated, or multi-reference systems where 75ksps suffices.

Availability

MAX189ACPA+ is available at Aetrix Electronics and suitable for portable data logging, isolated data acquisition, and high-accuracy process control requiring stable component supply across extended production lifecycles.

Supply support for MAX189ACPA+ 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 and mixed-signal ICs for industrial, medical, and communications applications, emphasizing low power, high integration, and robust performance.

The MAX187/MAX189 family was engineered specifically for low-power, space-constrained measurement systems needing reliable 12-bit digitization with minimal external components - targeting remote sensing and battery-operated instrumentation.

FAQ

What is the reference voltage requirement for MAX189ACPA+?

The MAX189ACPA+ requires an external reference voltage applied to the REF pin within the range of +2.5V to VDD (4.75–5.25V). Unlike the MAX187, it has no internal reference. For optimal accuracy, the reference must source ≤350µA DC load with ≤10Ω output impedance; a 0.1µF bypass capacitor is mandatory at the REF pin. The MAX189ACPA+ achieves ±½ LSB INL only when using a stable, low-noise reference such as the REF5025.

Does MAX189ACPA+ support SPI, QSPI, and MICROWIRE interfaces?

Yes, MAX189ACPA+ supports all three protocols via its 3-wire serial interface (CS, SCLK, DOUT). It operates with CPOL = 0 and CPHA = 0 for SPI/QSPI, and is compatible with MICROWIRE timing. Data is output MSB-first with a leading EOC bit, requiring exactly 13 SCLK falling edges for full 12-bit readout. No mode pins or configuration registers are needed - interface behavior is hardwired per Maxim's datasheet timing diagrams.

What is the maximum analog input frequency supported by MAX189ACPA+?

The MAX189ACPA+ has a 4.5MHz small-signal bandwidth and 75ksps sampling rate, permitting accurate digitization of input frequencies up to 37.5kHz (Nyquist limit) in baseband mode. For higher-frequency signals (e.g., RF IF stages), undersampling techniques can be applied - but require external anti-alias filtering to prevent spectral folding. The 10kHz FFT test condition yielding 70dB SINAD confirms usable dynamic performance within this band.

How does shutdown mode work on MAX189ACPA+?

Driving the SHDN pin low places MAX189ACPA+ into shutdown mode, reducing supply current to 2–10µA. The device wakes up in <2µs (t_WAKE) and is ready for conversion immediately after SHDN returns high - no re-initialization delay. During shutdown, the reference input remains active, allowing external reference circuits to stay powered. This behavior differs from the MAX187, which uses SHDN to enable/disable its internal reference.

Can MAX189ACPA+ be used with microcontrollers lacking hardware SPI?

Yes, MAX189ACPA+ is fully compatible with bit-banged GPIO implementations due to its simple timing: CS falling edge starts conversion; DOUT goes high at end-of-conversion (EOC); then 13 bits (EOC + 12 data) are clocked out on SCLK falling edges. No setup/hold complexity exists beyond t_CS (500ns min CS pulse width) and t_CH/t_CL (100ns min clock phase width). This makes MAX189ACPA+ viable for resource-limited MCUs like ATmega328P or MSP430G2553.