Analog Devices Inc./Maxim Integrated MAX6855UK24D3+T

Overview

The MAX6855UK24D3+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring active-high push-pull reset output, manual reset input (MR), and factory-trimmed 2.4V reset threshold with 150ms minimum reset timeout. It monitors VCC for brownout detection, asserts reset during power-up/down, and guarantees valid reset operation down to VCC = +1.1V. Designed for ultra-low-power portable systems including glucose monitors and patient monitors.

For engineers reviewing the MAX6855UK24D3+T datasheet, MAX6855UK24D3+T pinout, MAX6855UK24D3+T application, or MAX6855UK24D3+T equivalent, this page delivers verified technical context, exact pin functions, real-world timing behavior, and validated alternative options - all grounded in Maxim's official electrical characteristics and functional descriptions.

Technical Context

The MAX6855UK24D3+T implements a voltage-monitoring supervisor with a precision bandgap reference and internal hysteresis (0.5% of VTH) to prevent chatter near threshold. Its reset assertion is triggered solely by VCC falling below 2.4V ±2.5% or MR low assertion - no watchdog timer or CT input functionality is present, as confirmed by the Selector Guide and Pin Description tables.

It uses a fixed 150ms (min) reset timeout period (D3 option), with guaranteed tRD ≤40µs and tMRD = 250ns. The active-high push-pull RESET output is referenced to VCC and sinks ≤0.3V at ISINK = 1.2mA (VCC ≥ 2.38V), ensuring reliable µP reset signaling across its full 1.2V–5.5V operating range.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, -40°C to +85°C industrial temperature range.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K24DBVR and MAX6316LUK24D3+T, the MAX6855UK24D3+T uniquely delivers active-high push-pull reset without external components - eliminating level-shifting overhead and simplifying validation in medical-grade portable designs.

Availability

MAX6855UK24D3+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and portable ECG devices requiring stable component supply, long-term lifecycle support, and certified medical-grade traceability.

Supply support for MAX6855UK24D3+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6855UK24D3+T belongs to Maxim's nanopower µP supervisory family, engineered specifically for battery-critical portable medical electronics where ultra-low ICC, guaranteed brownout response, and minimal external components are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6855UK24D3+T?

The MAX6855UK24D3+T has a factory-trimmed reset threshold of 2.4V with ±2.5% tolerance (2.34V to 2.46V) over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) where suffix "24" corresponds to 2.4V nominal, and Electrical Characteristics specify VTH = VTH ±2.5%. The MAX6855UK24D3+T does not include watchdog or CT functionality - its behavior is strictly voltage-monitoring with manual reset.

Does the MAX6855UK24D3+T include a watchdog timer?

No, the MAX6855UK24D3+T does not include a watchdog timer. Per the Selector Guide and Pin Configurations, only MAX6864–MAX6869 variants feature WDI input; the MAX6855UK24D3+T is explicitly listed with "-" under WDI column. Its functionality is limited to VCC monitoring, manual reset (MR), and fixed 150ms reset timeout - consistent with MAX6854/MAX6855/MAX6856 series definitions in the General Description.

What does the "D3" in MAX6855UK24D3+T indicate?

The "D3" suffix in MAX6855UK24D3+T specifies the reset timeout period: 150ms (minimum), per Table 4 (Reset Timeout Periods). D3 corresponds to min/typ/max values of 150ms/225ms/300ms. This timeout begins after VCC rises above the 2.4V threshold or MR deasserts, and ensures the microprocessor remains held in reset long enough for power stabilization and clock settling.

Is the MAX6855UK24D3+T pin-compatible with other MAX68xx supervisory ICs?

The MAX6855UK24D3+T shares the same 5-pin SOT23-5 footprint with MAX6854/MAX6856/MAX6858/MAX6860–MAX6869, but pin functions differ. Specifically, Pin 1 is active-high RESET (not open-drain or active-low), and Pins 2 & 4 are both GND - unlike MAX6858/MAX6860 which use Pin 1 for I.C. and Pin 4 for RESET. Direct substitution requires verification of RESET polarity and GND connectivity per schematic.

What is the maximum VCC transient duration the MAX6855UK24D3+T can ignore?

The MAX6855UK24D3+T can ignore VCC transients ≤40µs in duration when the overdrive is 100mV (i.e., VCC falls from 2.5V to below 2.4V), as shown in Figure MAX684 toc05. This immunity is achieved via internal filtering and ensures robust operation in noisy DC-DC converter environments - critical for portable medical devices where EMI may couple into power rails.