Analog Devices Inc./Maxim Integrated MAX6858UK25D3+T

Overview

MAX6858UK25D3+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.5V reset threshold (±2.5%), and 150ms minimum reset timeout period. It monitors VCC voltage, asserts active-low push-pull RESET on brownout or manual trigger, and guarantees valid reset output down to VCC = +1.1V - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6858UK25D3+T datasheet, MAX6858UK25D3+T pinout, MAX6858UK25D3+T application, or MAX6858UK25D3+T equivalent, key selection criteria include its fixed 2.5V threshold, absence of watchdog timer or manual reset input, immunity to short VCC transients (<40µs at 100mV overdrive), and compatibility with low-voltage µP systems requiring guaranteed reset assertion below 1.2V.

Technical Context

The MAX6858UK25D3+T implements a precision bandgap-based voltage monitor with hysteresis (0.5% of VTH) and an internal RC timeout generator. Its reset assertion logic is triggered solely by VCC falling below 2.5V (±2.5%) - no MR or WDI inputs are present, distinguishing it from MAX6861–MAX6869 or MAX6864–MAX6869 variants.

It delivers push-pull active-low RESET output referenced to VCC, with VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.12V) and VOH ≥ 0.8×VCC at ISOURCE = 500µA. The device operates across -40°C to +85°C and remains functional down to VCC = 1.1V, enabling reliable supervision in deep-brownout conditions.

Key Specifications

Pinout & Package

MAX6858UK25D3+T is housed in a lead-free 5-pin SOT23-5 package (JEDEC MO-178AA). Pins 1 and 2 are internally connected (I.C.) for enhanced noise immunity and must be tied to GND. Pin 3 is GND, Pin 4 is active-low push-pull RESET output, and Pin 5 is VCC supply input.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6858UK25D3+T, TPS3836K25DBVR trades 10× higher supply current for superior ESD rating, while MAX6315US25D3+ sacrifices push-pull drive and noise immunity for open-drain flexibility - neither offers the same combination of nanopower operation, guaranteed 1.1V reset validity, and integrated I.C. grounding.

Availability

MAX6858UK25D3+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, wireless sensor nodes, and industrial handheld scanners requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6858UK25D3+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 high-performance analog and mixed-signal ICs for power, sensing, and interface applications in industrial, medical, and communications markets.

The MAX6854–MAX6869 family delivers nanopower supervisory functions for battery-critical systems; MAX6858UK25D3+T specifically targets cost-sensitive, low-complexity applications needing fixed 2.5V reset without manual or watchdog features.

FAQ

What is the exact reset threshold voltage of the MAX6858UK25D3+T?

The MAX6858UK25D3+T has a factory-trimmed reset threshold of 2.5V with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "25" corresponds to 2.438V (min), 2.500V (typ), and 2.563V (max). The MAX6858UK25D3+T uses this exact specification and does not incorporate manual reset or watchdog functionality.

Does the MAX6858UK25D3+T include a manual reset input (MR) or watchdog timer (WDI)?

No, the MAX6858UK25D3+T does not include MR or WDI inputs. Per the Selector Guide and Pin Configurations section, MAX6858 is defined as having no MR or WDI pins - only VCC, GND, RESET, and two internally connected (I.C.) pins. This distinguishes it from MAX6861–MAX6869 (MR + CT) and MAX6864–MAX6869 (MR + WDI) variants. The MAX6858UK25D3+T provides voltage supervision only.

What is the function of pins 1 and 2 on the MAX6858UK25D3+T?

Pins 1 and 2 of the MAX6858UK25D3+T are labeled "I.C." (Internally Connected) and must be externally tied to GND per the datasheet's Pin Description and Typical Operating Circuit. This connection improves noise immunity in portable medical devices. These pins carry no signal and are not left floating - their sole purpose is to reduce susceptibility to EMI in compact SOT23 layouts.

What reset timeout period is implemented in the MAX6858UK25D3+T?

The MAX6858UK25D3+T implements the D3 reset timeout option: 150ms (min), 225ms (typ), 300ms (max), as specified in Table 4 (Reset Timeout Periods). The "D3" in the part number explicitly denotes this timeout selection. This duration ensures sufficient hold time for µP power supply stabilization after brownout recovery, especially in systems with large decoupling capacitance.

Can the MAX6858UK25D3+T operate reliably below 1.8V supply voltage?

Yes, the MAX6858UK25D3+T is fully specified down to VCC = +1.2V and guarantees valid RESET assertion down to +1.1V, as stated in Absolute Maximum Ratings and Electrical Characteristics. Its 170nA supply current at 1.8V and operation at 1.2V make it suitable for supervising ultra-low-voltage µPs and ASICs in energy-harvesting or coin-cell applications - a key differentiator from higher-current supervisors.