Analog Devices Inc./Maxim Integrated MAX6856UK23D3

Overview

MAX6856UK23D3 from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.313V reset threshold (±2.5%), 150ms minimum reset timeout period, manual reset input (MR), and open-drain active-low RESET output. It monitors VCC in battery-powered medical and portable electronics to ensure reliable power-on reset and brownout recovery.

For engineers reviewing the MAX6856UK23D3 datasheet, MAX6856UK23D3 pinout, MAX6856UK23D3 application, or MAX6856UK23D3 equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), no external components requirement, and compatibility with 1.2V–5.5V supply rails.

Technical Context

The MAX6856UK23D3 implements a precision voltage monitor with hysteresis (0.5% of VTH) and a fixed 150ms reset timeout timer. Its open-drain RESET output requires an external pullup and remains asserted for the full timeout after VCC rises above 2.313V or MR deasserts.

It includes an internal 10kΩ pullup on MR, supports CMOS-logic-level manual reset triggering with 1µs minimum pulse width and 200ns glitch rejection, and guarantees valid reset assertion even as VCC falls to +1.1V - critical for low-voltage microcontroller operation.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free compatible (RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3838K23DBVR and STM6315SW13F, the MAX6856UK23D3 delivers the lowest supply current (170nA) and best combination of reset accuracy, timeout stability, and open-drain flexibility for battery-critical portable medical systems.

Availability

MAX6856UK23D3 is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and PDAs requiring stable component supply across long-lifecycle medical and consumer programs.

Supply support for MAX6856UK23D3 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 interface applications in industrial, medical, and communications markets.

The MAX6856UK23D3 belongs to the nanopower µP supervisory family engineered specifically for ultra-low-power, battery-operated portable electronics requiring guaranteed reset behavior under brownout and transient conditions.

FAQ

What is the exact reset threshold voltage of MAX6856UK23D3?

The MAX6856UK23D3 has a factory-trimmed reset threshold of 2.313V, with ±2.5% tolerance over the -40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "23" corresponds to 2.313V nominal. The device guarantees reset assertion when VCC falls below this threshold and release only after VCC exceeds it plus hysteresis (0.5% of VTH).

Does MAX6856UK23D3 include a watchdog timer?

No, the MAX6856UK23D3 does not include a watchdog timer. Per the Selector Guide and Pin Configurations section, MAX6856 variants (including MAX6856UK23D3) provide manual reset (MR) and voltage monitoring only. Watchdog functionality is exclusive to MAX6864–MAX6869 parts - e.g., MAX6864UK23D3S includes WDI input and 3.3s/209s watchdog timeout options.

What is the function of Pin 4 on MAX6856UK23D3?

Pin 4 on the MAX6856UK23D3 is a second ground (GND) terminal, electrically connected internally to Pin 2. Its inclusion improves noise immunity and thermal performance in high-density layouts by providing a dedicated return path for internal circuitry and reducing ground loop impedance - a design feature shared across the MAX6854/MAX6855/MAX6856 series in SOT23-5 package.

Can MAX6856UK23D3 drive a 1.8V microcontroller reset input?

Yes, the MAX6856UK23D3 can drive a 1.8V microcontroller reset input using its open-drain RESET output (Pin 1). Connect an external pullup resistor from Pin 1 to the 1.8V rail - the device sinks current when asserting reset and presents high-impedance when deasserted, enabling seamless level translation without additional logic. Ensure the pullup value (typically 10–100kΩ) balances rise time and power consumption.

What is the minimum VCC required for MAX6856UK23D3 to assert a valid reset signal?

The MAX6856UK23D3 guarantees valid reset assertion down to VCC = +1.1V, as explicitly stated in the Electrical Characteristics table and Applications Information section. Below this voltage, the internal comparator and timer may become unreliable. This specification ensures deterministic reset behavior during deep brownout events common in battery-discharge scenarios, distinguishing it from supervisory ICs requiring ≥1.2V or higher for reset validity.