Analog Devices Inc./Maxim Integrated MAX6858UK31D3+T

Overview

The MAX6858UK31D3+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 3.075V reset threshold (suffix "31"), and 150ms minimum reset timeout (suffix "D3"). It monitors VCC, asserts active-low push-pull RESET on undervoltage or manual reset, and guarantees valid reset operation down to VCC = +1.1V. It is used in battery-powered glucose monitors and portable medical devices requiring long-term power integrity.

For engineers reviewing the MAX6858UK31D3+T datasheet, MAX6858UK31D3+T pinout, MAX6858UK31D3+T application, or MAX6858UK31D3+T equivalent, key selection criteria include its fixed 3.075V threshold, 150ms reset timeout, absence of watchdog timer or manual reset input, and compatibility with low-voltage µP systems operating down to 1.1V.

Technical Context

The MAX6858UK31D3+T implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over temperature and 0.5% hysteresis to prevent chatter during brownout recovery. Its internal reset timer ensures deterministic deassertion timing after VCC exceeds the threshold, independent of supply ramp rate.

Unlike variants with MR or WDI pins, the MAX6858UK31D3+T omits both manual reset and watchdog functionality-its only inputs are VCC and GND, and its sole output is an active-low push-pull RESET referenced to VCC. This simplifies integration in space-constrained, single-supply monitoring applications where external intervention or software supervision is unnecessary.

Key Specifications

Pinout & Package

MAX6858UK31D3+T is housed in a lead-free 5-pin SOT23 package (JEDEC MO-178AA), with pins arranged as follows (top view): Pin 1 = I.C., Pin 2 = I.C., Pin 3 = GND, Pin 4 = RESET, Pin 5 = VCC. Internally connected (I.C.) pins must be tied to GND for optimal noise immunity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and ADM6806-30ARTZ-R7, the MAX6858UK31D3+T delivers the lowest supply current (170nA) and tightest integration for long-life battery applications, while maintaining identical SOT23-5 packaging and 3.0–3.3V monitoring capability - making it optimal for medical wearables where power budget is constrained.

Availability

MAX6858UK31D3+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, wearable health trackers, and industrial sensor nodes requiring stable component supply across extended production lifecycles.

Supply support for MAX6858UK31D3+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) designs precision analog and mixed-signal ICs for power management, sensing, and interface applications in industrial, medical, and communications markets.

The MAX685x family was engineered specifically for ultra-low-power microprocessor supervision in battery-critical medical and portable electronics, prioritizing nanoscale current consumption and guaranteed reset validity at sub-1.2V supply levels.

FAQ

What is the exact reset threshold voltage of the MAX6858UK31D3+T?

The MAX6858UK31D3+T has a factory-trimmed reset threshold voltage of 3.075V, with ±2.5% tolerance over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 ("Threshold Suffix Guide") of the datasheet, where suffix "31" corresponds to 3.075V (min 2.998V, typ 3.075V, max 3.152V). The MAX6858UK31D3+T does not require external resistor networks to set this threshold.

Does the MAX6858UK31D3+T include a manual reset input or watchdog timer?

No, the MAX6858UK31D3+T excludes both manual reset (MR) and watchdog input (WDI) functionality. As shown in the Selector Guide and Pin Configurations section, MAX6858 variants have only VCC, GND, RESET, and two internally connected (I.C.) pins - no MR or WDI terminals. This distinguishes it from MAX6864–MAX6869 (watchdog-enabled) and MAX6854/MAX6856 (MR-equipped) variants in the same family.

What is the reset timeout period for the MAX6858UK31D3+T?

The MAX6858UK31D3+T provides a fixed minimum reset timeout period of 150ms, as indicated by the "D3" suffix per Table 4 ("Reset Timeout Periods"). Typical and maximum values are 225ms and 300ms respectively. This timeout begins when VCC rises above the 3.075V threshold and ensures the microprocessor remains held in reset long enough to complete internal power stabilization and clock startup.

Can the MAX6858UK31D3+T operate reliably below 1.2V?

Yes - the MAX6858UK31D3+T guarantees valid reset assertion down to VCC = +1.1V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. While the recommended operating range starts at 1.2V, the device continues to monitor and assert RESET correctly at 1.1V, enabling robust brownout detection in deeply discharged battery scenarios where other supervisors fail.

Is the MAX6858UK31D3+T pin-compatible with other SOT23-5 supervisory ICs?

The MAX6858UK31D3+T uses a nonstandard pinout: Pins 1 and 2 are internally connected (I.C.) and must be tied to GND, Pin 3 is GND, Pin 4 is RESET, and Pin 5 is VCC. This differs from conventional SOT23-5 supervisory ICs (e.g., TPS3836) that use Pin 1 for VCC or RESET. Direct pin-to-pin replacement is not possible without PCB modification; however, the 5-pin SOT23 package outline matches JEDEC MO-178AA for mechanical compatibility.