Analog Devices Inc./Maxim Integrated MAX6861UK29-T

Overview

The MAX6861UK29-T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.925V reset threshold (suffix "29"), and pin-selectable 10ms/150ms minimum reset timeout via CT input. It monitors VCC, responds to manual reset (MR), and asserts an active-low push-pull RESET output - ideal for battery-powered glucose monitors and portable medical devices requiring reliable brownout protection.

For engineers reviewing the MAX6861UK29-T datasheet, MAX6861UK29-T pinout, MAX6861UK29-T application, or MAX6861UK29-T equivalent, key selection criteria include its 2.925V threshold accuracy (±2.5%), guaranteed RESET validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), and compatibility with low-voltage µP systems operating from 1.2V to 5.5V.

Technical Context

This device integrates voltage monitoring, manual reset assertion, and a fixed-function reset timeout generator - but no watchdog timer (MAX6864–MAX6869 only). Its CT pin selects between two factory-set timeout options (D1 = 10ms min or D3 = 150ms min), enabling design flexibility without external components.

The internal reset comparator operates reliably across -40°C to +85°C, with hysteresis of 0.5% VTH and VCC-to-RESET delay under 40µs. The push-pull RESET output drives low to ≤0.3V at 1.2mA sink (VCC ≥ 2.38V) and high to ≥0.8×VCC at 500µA source, ensuring robust interface with modern low-voltage microcontrollers.

Key Specifications

Pinout & Package

MAX6861UK29-T uses a 5-pin SOT23 package (JEDEC MO-178AA), with 1.3mm × 2.9mm footprint and 0.95mm height. Pin 1 is marked with a dot; pin numbering follows standard SOT23 convention (counterclockwise from mark).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and STM6315RWX6F, the MAX6861UK29-T delivers the lowest supply current (170nA) and pin-selectable timeout flexibility - making it optimal for long-life battery-powered medical and IoT edge devices where every nanoamp matters and timeout tuning is needed per firmware version.

Availability

MAX6861UK29-T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, wireless sensor nodes, and industrial handheld terminals requiring stable component supply across extended production lifecycles.

Supply support for MAX6861UK29-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

Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in portable and battery-critical systems - emphasizing nanopower operation, small footprint, and robust reset timing under real-world voltage transients.

FAQ

What is the exact reset threshold voltage of the MAX6861UK29-T?

The MAX6861UK29-T has a factory-trimmed reset threshold voltage of 2.925V, with guaranteed tolerance of ±2.5% over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the official datasheet, where suffix "29" corresponds to 2.925V nominal. The MAX6861UK29-T maintains this accuracy without requiring external calibration or trimming components.

Does the MAX6861UK29-T include a watchdog timer function?

No, the MAX6861UK29-T does not include a watchdog timer. Watchdog functionality is exclusive to the MAX6864–MAX6869 variants (e.g., MAX6864UK29D3S), which feature WDI input and selectable watchdog timeout periods. The MAX6861UK29-T belongs to the MAX6861/MAX6862/MAX6863 subgroup, which provides only voltage monitoring, manual reset (MR), and pin-selectable reset timeout via the CT input - as documented in the Selector Guide and Pin Description sections.

How is the reset timeout period selected on the MAX6861UK29-T?

The reset timeout period on the MAX6861UK29-T is selected using the CT (Control Time) pin: connect CT to GND for 10ms minimum timeout (D1 option), or connect CT to VCC for 150ms minimum timeout (D3 option). This selection is static and effective immediately upon power-up or reset assertion. The MAX6861UK29-T datasheet specifies these values as 10/15ms/25ms (min/typ/max) and 150/225/300ms (min/typ/max), respectively - confirmed in Table 1 and Electrical Characteristics.

What is the maximum supply voltage the MAX6861UK29-T can monitor?

The MAX6861UK29-T can monitor supply voltages from 1.2V to 5.5V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Its internal reset comparator remains functional across this full range, and the RESET output is guaranteed valid down to VCC = +1.1V. This makes the MAX6861UK29-T suitable for monitoring both low-voltage logic rails (e.g., 1.8V) and higher-voltage analog supplies (e.g., 5.0V) without external level-shifting circuitry.

Is the MAX6861UK29-T pin-compatible with other supervisory ICs?

Yes, the MAX6861UK29-T is pin-compatible with the Texas Instruments TPS3836/TPS3837/TPS3838 series in the 5-pin SOT23 package, as explicitly stated in the Features section of the datasheet. Pin functions (VCC, GND, MR, RESET, CT) map directly to corresponding pins on those TI parts - though CT replaces the unused pin on TPS383x devices. This allows direct substitution in existing layouts where timeout flexibility or lower ICC is desired, provided firmware accommodates the CT pin configuration.