Analog Devices Inc./Maxim Integrated MAX132CNG

Overview

MAX132CNG from Maxim Integrated is an 18-bit plus sign, multi-slope integrating analog-to-digital converter (ADC) with serial interface, ±512mV full-scale input range (2µV/LSB), 100 conversions/sec max throughput, and 15µV_RMS noise. It operates from ±5V supplies, draws only 60µA in normal mode and 1µA in sleep mode, and is used in precision weigh scales and battery-powered data loggers.

For engineers reviewing the MAX132CNG datasheet, MAX132CNG pinout, MAX132CNG application, or MAX132CNG equivalent, key selection considerations include its 50Hz/60Hz line rejection capability, programmable digital outputs (P0–P3), twos-complement bipolar output coding, and guaranteed ±0.006% FSR accuracy at 16 conv/sec - all critical for low-noise, high-resolution industrial measurement systems.

Technical Context

The MAX132CNG uses multi-slope integration with fixed-integration time followed by reference deintegration, enabling high resolution without sacrificing speed. Its 50Hz/60Hz mode selection bit configures integration periods to exactly one AC line cycle (20ms or 16.67ms) using a 32.768kHz crystal, delivering inherent line-frequency rejection.

It features a pseudo-differential analog input (IN HI/IN LO), ±2pA typical input bias current, and internal oscillator supporting external crystal or clock. Four user-programmable digital outputs (P0–P3) are controlled via serial command register, enabling direct control of external multiplexers or PGAs without additional logic.

Key Specifications

Pinout & Package

MAX132CNG is housed in a 24-pin narrow plastic DIP (0.300" width), RoHS-compliant, commercial temperature grade (0°C to +70°C).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-resolution integrating ADC applications.

Compared with MAX132CNG, ADS1258IRTCR offers higher resolution but demands more external components and lacks native line-rejection timing, while LTC2440IGN#PBF achieves lower noise but omits the integrated programmable outputs essential for compact sensor-system integration.

Availability

MAX132CNG is available at Aetrix Electronics and suitable for precision weigh scales, battery-powered data loggers, and industrial process controllers requiring stable component supply with long lifecycle visibility.

Supply support for MAX132CNG 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 demanding industrial, medical, and instrumentation applications.

The MAX132CNG belongs to Maxim's high-accuracy integrating ADC product line, engineered specifically for low-power, high-resolution DC measurement systems where line-frequency interference and sensor offset drift are primary design constraints.

FAQ

What is the guaranteed accuracy specification for MAX132CNG at its rated conversion rate?

The MAX132CNG is guaranteed for ±0.006% FSR integral nonlinearity at 16 conversions per second under specified conditions (V+ = 5V, V− = −5V, f_CLK = 32.768kHz, 60Hz mode). This accuracy includes effects of zero error, rollover error, and scale factor drift across the 0°C to +70°C commercial temperature range. The MAX132CNG achieves this performance without trimming or calibration components, relying on multi-slope integration stability.

How does the MAX132CNG achieve 50Hz and 60Hz line-frequency rejection?

The MAX132CNG achieves 50Hz/60Hz rejection by configuring its integration period to exactly one AC line cycle: 20ms for 50Hz (655 clock counts) or 16.67ms for 60Hz (545 clock counts), using a 32.768kHz crystal. This is controlled by the 50Hz/60Hz mode bit in Command Input Register 0. The MAX132CNG performs charge-balancing integration that inherently cancels periodic interference within the integration window - no external notch filters or DSP required.

Can the MAX132CNG operate with a reference voltage other than 545mV or 655mV?

Yes, the MAX132CNG accepts reference voltages from 500mV to 700mV, though 545mV (60Hz mode) and 655mV (50Hz mode) are the nominal values tested and guaranteed. Using references outside this range degrades performance: voltages below 500mV reduce signal-to-noise ratio, while those above 700mV increase rollover error. The MAX132CNG reference inputs (REF+, REF−) tolerate voltages anywhere within the supply rails, but best linearity is achieved when neither reference pin is within 2V of V+ or V−.

What is the function of the P0–P3 pins on the MAX132CNG, and how are they controlled?

The P0–P3 pins on the MAX132CNG are user-programmable digital outputs controlled exclusively via Command Input Register 1. Bits D4–D7 of that register directly set the logic state of P0–P3, respectively. These outputs remain latched until reprogrammed and can drive external devices such as analog multiplexers (e.g., DG408), programmable-gain amplifiers (e.g., PGA204), or LED indicators - eliminating the need for discrete GPIO expanders in space-constrained designs.

Does the MAX132CNG require an external integrator resistor and capacitor, and what are the recommended values?

Yes, the MAX132CNG requires external R_INT and C_INT. For operation with a 32.768kHz crystal and 545mV/655mV reference, Maxim specifies a 602kΩ metal-film resistor and 4.7nF polypropylene capacitor. These values set the integrator current (<2.5µA) and output swing (~3V) to avoid saturation while maintaining optimal linearity. The MAX132CNG datasheet provides scaling equations for alternate crystal frequencies or reference voltages, and warns against polyester capacitors due to dielectric absorption-induced nonlinearity.