Analog Devices Inc./Maxim Integrated MAX6855UK40D4+T

Overview

The MAX6855UK40D4+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input (MR), and active-low push-pull reset output. It asserts reset when VCC drops below its factory-trimmed 4.000V threshold, when MR is pulled low, or during power-up/brownout - with a guaranteed minimum 1200ms reset timeout period and valid operation down to VCC = +1.1V. It targets ultra-low-power portable medical and consumer devices requiring reliable, glitch-immune reset control.

For engineers reviewing the MAX6855UK40D4+T datasheet, MAX6855UK40D4+T pinout, MAX6855UK40D4+T application, or MAX6855UK40D4+T equivalent, this page delivers verified technical context, exact pin functions, real-world timing behavior, and validated alternative options for battery-powered system design and BOM optimization.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% reset threshold accuracy over -40°C to +85°C, coupled to a digital timeout counter that holds reset asserted for ≥1200ms after VCC exceeds 4.000V and MR deasserts. Its 170nA typical supply current enables multi-year operation on coin cells, while immunity to ≤40µs VCC transients ensures robustness in noisy environments.

The MAX6855UK40D4+T features an internally pulled-up MR input (10kΩ to VCC), supports CMOS-logic-level manual reset triggering, and guarantees RESET output validity down to VCC = +1.1V - enabling safe initialization of low-voltage µPs before full rail stabilization.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and MAX6369KA29D3+T, the MAX6855UK40D4+T uniquely delivers 4.000V precision threshold, 1200ms timeout, and 170nA ICC in one SOT23-5 package - making it irreplaceable for long-life, 4V-class portable medical devices requiring manual reset.

Availability

The MAX6855UK40D4+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and low-power consumer electronics requiring stable component supply across extended production lifecycles.

Supply support for MAX6855UK40D4+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 high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications markets.

The MAX6855UK40D4+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for ultra-low-power portable and medical applications where multi-year battery life and precise voltage monitoring are critical.

FAQ

What is the exact reset threshold voltage of the MAX6855UK40D4+T?

The MAX6855UK40D4+T has a factory-trimmed reset threshold voltage of 4.000V, 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 datasheet, where suffix "40" corresponds to 4.000V nominal. The MAX6855UK40D4+T uses this precise threshold to protect 3.3V/5V systems against brownout conditions without false triggering.

Does the MAX6855UK40D4+T include a watchdog timer function?

No, the MAX6855UK40D4+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input and watchdog functionality. The MAX6855UK40D4+T is a manual-reset-only supervisory circuit with MR input and push-pull active-low RESET output - confirmed by its absence in the WDI column of the Selector Guide and lack of WDI pin in its pin configuration diagram.

What is the minimum reset timeout period for the MAX6855UK40D4+T?

The MAX6855UK40D4+T has a minimum reset timeout period of 1200ms, corresponding to timeout option "D4" per Table 4 (Reset Timeout Periods). This is explicitly encoded in the part number suffix "D4", and the datasheet specifies D4 as 1200ms (min), 1800ms (typ), and 2400ms (max). This long timeout ensures reliable µP initialization in systems with slow power-rail ramp-up or complex bootloader sequences.

Is the MAX6855UK40D4+T pin-compatible with other MAX68xx devices?

The MAX6855UK40D4+T shares the same 5-pin SOT23-5 package and pinout (VCC, GND, MR, GND, RESET) with MAX6854/MAX6856/MAX6861–MAX6863, but differs from MAX6864–MAX6869 (which replace one GND with WDI) and MAX6858/MAX6860 (which use I.C. pins instead of MR). Pin compatibility is limited to the MR-enabled subgroup; substitution requires verifying identical reset output type (active-low push-pull) and threshold - the MAX6855UK40D4+T is not pin-compatible with MAX6864UKxxDxS variants.

What is the guaranteed operating voltage range for the MAX6855UK40D4+T?

The MAX6855UK40D4+T operates across a supply voltage range of 1.2V to 5.5V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Critically, its reset output remains valid down to VCC = +1.1V - enabling robust supervision even during deep battery discharge. This 1.2V–5.5V range supports direct integration with Li-ion, alkaline, and coin-cell power sources without external regulation.