Analog Devices Inc./Maxim Integrated MAX6422US33+T

Overview

MAX6422US33+T from Analog Devices is a low-power, active-high push-pull microprocessor supervisor IC that monitors 3.3V system supplies and asserts a reset signal when VCC falls below 3.30V (±2.5% over temperature), with capacitor-adjustable timeout (3.0–5.75ms at CSRT = 1500pF), 1.6µA typical quiescent current, and guaranteed operation down to VCC = 1V - used in battery-powered controllers and portable equipment for reliable power-up sequencing.

For engineers reviewing the MAX6422US33+T datasheet, MAX6422US33+T pinout, MAX6422US33+T application, or MAX6422US33+T equivalent, key selection criteria include its 4-pin SOT143 package, active-high push-pull RESET output, ±2.5% reset threshold accuracy over –40°C to +125°C, capacitor-set timeout flexibility, and immunity to sub-50µs VCC transients exceeding 100mV below threshold.

Technical Context

The MAX6422US33+T implements a precision voltage detector with laser-trimmed internal resistors defining a 3.30V nominal reset threshold, referenced to an internal 0.65V bandgap. Its reset assertion logic is triggered by VCC falling below VTH, and deassertion follows a ramp-controlled timeout determined by external capacitor CSRT charging via a 240nA current source.

Unlike open-drain variants, the MAX6422US33+T features a push-pull output stage capable of sourcing up to 800µA at VCC ≥ 4.5V while maintaining VOH ≥ 0.8×VCC and VOL ≤ 0.4V at ISINK = 3.2mA - enabling direct interface to CMOS µP reset inputs without external pull-ups.

Key Specifications

Pinout & Package

MAX6422US33+T is housed in a 4-pin SOT143 package (package code U4+1), measuring 2.1mm × 2.3mm × 0.95mm, with gull-wing leads and RoHS-compliant lead-free finish ("+T" suffix).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisor applications.

Compared with MAX6421US33+T, the MAX6422US33+T provides native active-high signaling for direct µP compatibility, while TLV803EB33DBZR trades adjustability for ultra-low current and smaller footprint - making MAX6422US33+T optimal for designs needing both timing flexibility and push-pull drive strength without logic inversion.

Availability

MAX6422US33+T is available at Aetrix Electronics and suitable for battery-powered portable controllers, automotive body electronics, and medical infusion pump controllers requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6422US33+T 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

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets with precision signal chain solutions.

The MAX6422US33+T belongs to the MAX6340/MAX6421–MAX6426 family of low-power microprocessor supervisors designed specifically for reliable power-monitoring in space- and energy-constrained embedded systems operating across extended temperature ranges.

FAQ

What is the exact reset threshold voltage of the MAX6422US33+T?

The MAX6422US33+T has a nominal reset threshold of 3.30V, with ±1.5% accuracy at +25°C and ±2.5% accuracy over the full operating temperature range of –40°C to +125°C. This value is laser-trimmed at wafer test and confirmed in the Electrical Characteristics table under "VCC Reset Threshold Accuracy" (VTH). The "33" suffix in the part number explicitly denotes the 3.30V threshold variant per Table 1 in the datasheet.

Can the MAX6422US33+T operate with a 1.8V supply?

Yes, the MAX6422US33+T operates with supply voltages from 1.0V to 5.5V, including 1.8V. Its reset output remains valid down to VCC = 1V, and quiescent current is specified at 1.9µA (typ) for VCC ≤ 3.3V. However, the 3.30V threshold means it will assert reset whenever VCC falls below ~3.22V (minimum threshold at temperature), so it is not intended for monitoring 1.8V rails - use a lower-threshold variant like MAX6422US18+T instead.

How do I calculate the external capacitor value for a 10ms reset timeout with the MAX6422US33+T?

To achieve a 10ms reset timeout (tRP = 0.01s), use the formula CSRT = (tRP − 275µs) / 2.735 × 10⁶, yielding CSRT ≈ 3.55nF. Select a low-leakage ceramic capacitor (X7R or C0G, <10nA leakage) and place it as close as possible to the SRT pin with minimal trace length. Verify timing with oscilloscope measurement, as actual tRP varies slightly with temperature and capacitor tolerance.

Is the MAX6422US33+T pin-compatible with other parts in the MAX642x family?

The MAX6422US33+T shares the same 4-pin SOT143 pinout as MAX6421USxx+T and MAX6423USxx+T variants, with identical VCC, GND, RESET, and SRT assignments. However, output polarity differs: MAX6422US33+T has active-high push-pull RESET, while MAX6421US33+T is active-low and MAX6423US33+T is open-drain - direct substitution requires firmware or schematic review to ensure logic compatibility.

Does the MAX6422US33+T require an external pull-up resistor on the RESET pin?

No, the MAX6422US33+T features an active-high push-pull RESET output and does not require an external pull-up resistor. Its output actively drives high (VOH ≥ 0.8×VCC) and low (VOL ≤ 0.4V), enabling direct connection to standard CMOS µP reset inputs. This distinguishes it from open-drain variants like MAX6423US33+T, which mandate a pull-up for proper logic-level translation.