Analog Devices Inc./Maxim Integrated MAX6682MUA+

Overview

MAX6682MUA+ from Maxim Integrated is a thermistor-to-digital converter IC that directly digitizes temperature-dependent resistance of NTC thermistors using an internal 10-bit ADC and precision voltage reference. It delivers 10-bit + sign output (11-bit word), achieves ±3 LSB total unadjusted error, operates from -55°C to +125°C, and supports 0.125°C resolution over 0°C to +50°C when paired with R_EXT = 7680Ω and standard 10kΩ thermistors-used in HVAC sensor modules and battery pack thermal monitoring.

For engineers reviewing the MAX6682MUA+ datasheet, MAX6682MUA+ pinout, MAX6682MUA+ application, or MAX6682MUA+ equivalent, this page provides verified technical context, SPI interface timing constraints, thermistor linearity optimization guidance, standby current (21µA typ), and real-world accuracy data across defined temperature ranges.

Technical Context

The MAX6682MUA+ implements a dedicated analog front-end where the internal 1.22V reference drives a thermistor–R_EXT voltage divider; it measures V_REXT (not thermistor voltage) and computes DOUT = 0.174387 × (V_REXT/V_R+) − 0.010404 × 8. Conversion time is fixed at 64–80ms, and the device powers down reference and analog circuitry between conversions.

Its SPI-compatible 3-wire interface outputs 11 bits (D10–D0) on SO with MSB-first timing: CS low initiates read, SCK up to 5MHz clocks data on rising edge, and SO enters high-Z after 11th cycle. The IC is read-only-no register writes-and features rail-to-rail output drivers with VOH ≥ VCC − 0.4V and VOL ≤ 0.4V at 1.6mA.

Key Specifications

Pinout & Package

The MAX6682MUA+ is housed in an 8-pin µMAX package (3mm × 3mm, 0.8mm height, exposed pad), compatible with standard SO-8 reflow profiles and suitable for space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar thermistor-to-digital conversion applications.

Compared with MAX31865 and ADS1118, the MAX6682MUA+ delivers plug-and-play NTC digitization with factory-aligned °C scaling, ultra-low self-heating, and no calibration code-reducing firmware development time by ~40 hours and eliminating external bias resistors.

Availability

MAX6682MUA+ is available at Aetrix Electronics and suitable for HVAC sensor modules, medical patient temperature monitors, and lithium-ion battery pack thermal monitoring requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for MAX6682MUA+ 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 U.S.-based semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, medical, and automotive applications.

The MAX6682MUA+ belongs to Maxim's precision temperature sensing product line, designed specifically to simplify high-accuracy thermistor interfacing in cost-sensitive, space-constrained systems without sacrificing measurement integrity.

FAQ

What is the maximum thermistor self-heating error achievable with the MAX6682MUA+?

The MAX6682MUA+ limits thermistor self-heating to approximately 0.0015°C under typical conditions (e.g., 10kΩ thermistor at +40°C with R_EXT = 5110Ω and 5V bias), due to its <2% duty-cycle excitation and low 1.22V reference. This is confirmed in the datasheet's Thermal Considerations section and contrasts sharply with continuous-bias approaches yielding >1°C error. The MAX6682MUA+ achieves this by powering the thermistor only during the 64–80ms conversion window.

Does the MAX6682MUA+ require external calibration for accurate temperature readings?

No, the MAX6682MUA+ does not require external calibration when used with standard 10kΩ NTC thermistors (e.g., Betatherm 10K3A1) and the recommended R_EXT = 7680Ω. Its output is pre-scaled to deliver direct °C-equivalent values (e.g., DOUT = 0x0500 = +40.000°C) over 0°C to +50°C with ≤0.2°C linearity error. Calibration is only needed if nonstandard thermistors or custom R_EXT values are used.

Can the MAX6682MUA+ interface directly with a 1.8V microcontroller?

No-the MAX6682MUA+ requires VCC between 3.0V and 5.5V and specifies VIH = 0.8×VCC and VIL = 0.2×VCC. At 3.0V VCC, VIH = 2.4V minimum, making direct connection to 1.8V logic unsafe. A level-shifter or 3.3V-compatible MCU is required. The SO output VOH is VCC − 0.4V (≥2.6V at 3.0V), which exceeds 1.8V logic-high thresholds but violates input voltage limits for 1.8V GPIO pins.

What is the purpose of the I.C. pin (Pin 1) on the MAX6682MUA+?

Pin 1 (I.C.) is an internally connected test node with no functional role in normal operation. The datasheet explicitly states it should be left unconnected or tied to GND-no current sourcing/sinking or signal routing is permitted. It is not a power, ground, or control pin, and connecting it to any active signal may compromise device reliability or measurement accuracy.

How does the MAX6682MUA+ handle power-supply noise, and what bypassing is required?

The MAX6682MUA+ uses an internal bandgap reference isolated from the VCC path, making it highly immune to supply noise-measurements show <0.2°C error even with 250mV_P-P square-wave noise at 1MHz applied to VCC without bypassing. However, a 0.1µF ceramic capacitor must still be placed between VCC and GND, as close as possible to Pin 8, to stabilize the internal regulator and ensure timing compliance per Figure 5 timing diagrams.