Analog Devices Inc./Maxim Integrated MAX189CCWE

Overview

MAX189CCWE from Maxim Integrated is a 12-bit successive-approximation analog-to-digital converter (ADC) operating from a single +5V supply, accepting 0–5V analog input with internal track/hold and 75ksps throughput. It requires an external reference voltage (2.5V to VDD), features a 3-wire SPI/QSPI/MICROWIRE-compatible serial interface, and delivers ±½ LSB integral nonlinearity (A-grade) for precision sensor digitization in battery-powered instrumentation.

For engineers reviewing the MAX189CCWE datasheet, MAX189CCWE pinout, MAX189CCWE application, or MAX189CCWE equivalent, this page provides verified technical context, real-world timing behavior, reference interface constraints, shutdown wake-up latency, and validated alternative options for low-power, space-constrained data acquisition designs.

Technical Context

The MAX189CCWE implements a 12-bit SAR architecture with integrated track/hold circuitry acquiring signals in ≤1.5µs, using an external clock up to 5MHz for serial data readout. Its unipolar conversion range is strictly defined by the externally applied reference voltage at the REF pin (2.5V to VDD), and it supports no internal reference-unlike the MAX187.

Conversion is initiated by a falling edge on CS; DOUT transitions high to signal end-of-conversion (EOC), after which 13 serial clock cycles (MSB-first, including leading EOC bit) shift out the result. The device enters shutdown mode when SHDN is pulled low, drawing ≤10µA, and wakes in time dependent on external reference capacitor discharge-no internal reference settling delay applies.

Key Specifications

Pinout & Package

MAX189CCWE is housed in a 16-pin wide SO (SOIC-W) package with exposed pad (not electrically connected). Pin functions are fully decoupled between analog and digital domains: AGND (Pin 10) and DGND (Pin 11) must be tied at a single point; REF (Pin 8) accepts external reference only; SHDN (Pin 6) controls power state; AIN (Pin 3) is sampled via internal track/hold.

Key Features

Applications

Equivalent & Alternatives

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

Compared with the MAX189CCWE, the ADS7822U offers higher throughput at increased quiescent current, while the AD7490BRUZ adds multiplexing and internal reference at the expense of design flexibility in isolated or ratiometric reference configurations.

Availability

MAX189CCWE is available at Aetrix Electronics and suitable for portable data logging, remote DSP, isolated data acquisition, and high-accuracy process control requiring stable component supply, long-term lifecycle assurance, and guaranteed traceable sourcing.

Supply support for MAX189CCWE 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/MAX189 product line was engineered for low-power, space-constrained data acquisition systems requiring high DC accuracy and simple serial interfacing-especially where external reference control or isolation is critical.

FAQ

Does the MAX189CCWE include an internal voltage reference?

No, the MAX189CCWE does not include an internal voltage reference. Unlike the MAX187, it requires an external reference voltage applied to the REF pin within the 2.5V to VDD range. The MAX189CCWE's REF pin has 12–20kΩ input resistance and must be bypassed with at least 0.1µF; using a 4.7µF capacitor is recommended if the reference source exhibits noise or high output impedance. This external reference dependency is fundamental to the MAX189CCWE's design and enables ratiometric measurements and system-level reference sharing.

What is the maximum allowed source impedance driving AIN on the MAX189CCWE?

The MAX189CCWE specifies that analog source impedance driving AIN should be ≤5kΩ to maintain full AC performance and avoid extended acquisition time. The device's internal track/hold uses a 16pF hold capacitor, and acquisition time lengthens proportionally with source resistance per t_ACQ = 9 × (R_S + R_IN) × 16pF, where R_IN = 5kΩ. Exceeding 5kΩ increases t_ACQ beyond the guaranteed 1.5µs, risking missing codes or reduced SINAD. For high-impedance sensors, a unity-gain buffer such as the MAX427 or OP27 is recommended ahead of AIN.

How many clock cycles are required to read a complete conversion from the MAX189CCWE?

Exactly 13 clock cycles are required to read a complete conversion from the MAX189CCWE. The serial output begins with a leading high bit (end-of-conversion indicator), followed by the 12-bit conversion result in MSB-first order. Each falling edge of SCLK shifts one bit onto DOUT, so 13 falling edges are necessary to retrieve all bits. Extra clocks after the 13th produce trailing zeros only if CS remains low; raising CS after the 13th falling edge terminates the transfer cleanly. This 13-cycle requirement is fixed and independent of clock frequency (up to 5MHz).

Can the MAX189CCWE operate with a 3.3V supply?

No, the MAX189CCWE is specified only for +4.75V to +5.25V operation. Its absolute maximum VDD rating is +6V, and its electrical characteristics-including reference input range, digital input thresholds, and internal biasing-are characterized exclusively at VDD = +5V ±5%. Operating at 3.3V violates the datasheet's supply voltage specification and will result in undefined behavior, including failure to acquire or convert, incorrect logic levels on CS/SCLK/DOUT, and potential damage due to improper internal node biasing. For 3.3V systems, consider alternatives like the ADS7822U or AD7490.

What happens to the MAX189CCWE's REF pin when SHDN is pulled low?

When SHDN is pulled low on the MAX189CCWE, the device enters shutdown mode and draws ≤10µA supply current, but the REF pin remains high-impedance and continues to accept the externally applied reference voltage. No internal circuitry connects to or buffers REF during shutdown-the external reference source must remain active and stable. This behavior differs from the MAX187, where SHDN controls internal reference enable/disable. For the MAX189CCWE, REF functionality is entirely independent of SHDN state, enabling seamless wake-up without reference re-stabilization delay.