Analog Devices Inc./Maxim Integrated MAX6422US29

Overview

MAX6422US29 from Maxim Integrated is a low-power microprocessor supervisor IC that monitors VCC supply voltage and asserts an active-high push-pull RESET signal when voltage falls below 2.925V (typical), with capacitor-adjustable reset timeout (3.0–5.75ms at CSRT = 1500pF), guaranteed operation down to VCC = 1V, and 1.6µA typical quiescent current - used in battery-powered controllers and portable equipment for reliable power-up sequencing.

For engineers reviewing the MAX6422US29 datasheet, MAX6422US29 pinout, MAX6422US29 application, or MAX6422US29 equivalent, key selection criteria include its 2.925V reset threshold accuracy (±1.5% at +25°C), SC70-4/SOT143-4 package compatibility, active-high push-pull output drive capability (VOH ≥ 0.8×VCC), and immunity to sub-50µs VCC transients exceeding 100mV below threshold.

Technical Context

The MAX6422US29 implements a precision voltage-detection circuit with laser-trimmed internal resistors to set its 2.925V nominal reset threshold, referenced to a stable 0.65V internal bandgap. Its reset assertion logic is triggered by VCC falling below VTH, and deassertion is delayed by a 240nA current source charging an external SRT capacitor to 0.65V.

This architecture ensures monotonic reset behavior across -40°C to +125°C, with ±2.5% threshold tolerance over temperature and <80µs VCC-to-reset delay during fast supply drops. The push-pull output drives high to VCC (≥0.8×VCC at 200µA) and low to ≤0.3V (at 500µA), eliminating need for external pull-ups.

Key Specifications

Pinout & Package

MAX6422US29 is housed in a 4-pin SC70-4 package (package code X4+1, outline 21-0098), with pin 1 = VCC, pin 2 = GND, pin 3 = RESET, pin 4 = SRT. The SRT pin accepts an external capacitor to set reset timeout; RESET is active-high push-pull; no NC pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6422US29, MAX6421US29+T offers identical supervision accuracy and timing but requires active-low reset handling, while TLV803EB29DBZR trades timeout adjustability for lower cost and smaller size - making MAX6422US29 optimal when precise, user-configurable reset hold time and active-high drive are required.

Availability

MAX6422US29 is available at Aetrix Electronics and suitable for portable equipment, battery-powered controllers, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6422US29 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 power, sensing, and connectivity in demanding environments.

The MAX6421–MAX6426 family delivers ultra-low-power, capacitor-programmable reset supervisors optimized for battery-critical and thermally harsh applications including portable medical, automotive, and industrial edge devices.

FAQ

What is the exact reset threshold voltage of MAX6422US29 and how is it trimmed?

The MAX6422US29 has a nominal reset threshold of 2.925V, with ±1.5% accuracy at +25°C and ±2.5% over -40°C to +125°C. This value is set by factory laser-trimming of internal precision resistors during wafer test, ensuring tight tolerance without external components. The "29" suffix in MAX6422US29 directly references the 2.925V threshold per Table 1 in the datasheet.

Can MAX6422US29 operate reliably when VCC drops below 1.8V?

Yes, MAX6422US29 guarantees valid RESET assertion and deassertion down to VCC = 1.0V, including full output drive strength (VOH ≥ 0.8×VCC, VOL ≤ 0.3V) and accurate threshold detection. This makes MAX6422US29 suitable for deep-brownout monitoring in systems with wide-input DC-DC converters or fading battery supplies.

How do I calculate the SRT capacitor value for a 4.0ms reset timeout with MAX6422US29?

Use the formula CSRT = (tRP − 275µs) / 2.73×10⁶, where tRP is in seconds. For 4.0ms: CSRT = (0.004 − 0.000275) / 2,730,000 ≈ 1365pF. A standard 1500pF ceramic capacitor yields ~4.375ms (within datasheet spec), and MAX6422US29 requires low-leakage (<10nA) dielectric - X7R or C0G types are recommended.

Is MAX6422US29 pin-compatible with other parts in the MAX642x family?

MAX6422US29 shares the same 4-pin SC70-4 and SOT143-4 pinouts with MAX6421US29+T and MAX6423US29+T, differing only in RESET polarity (active-high vs. active-low vs. open-drain). No PCB redesign is needed when substituting among these - only firmware or downstream logic may require adjustment for RESET polarity.

Does MAX6422US29 require external components to function as a basic supervisor?

MAX6422US29 operates as a functional supervisor with only VCC, GND, and RESET connected; the SRT pin may be left unconnected for minimum timeout (~275µs). However, for controlled reset hold time, a capacitor must be placed between SRT and GND. No pull-up/pull-down resistors are needed due to its push-pull output - unlike open-drain variants such as MAX6423US29+T.