Analog Devices Inc./Maxim Integrated MAX6705RKA+T

Overview

MAX6705RKA+T from Maxim Integrated is a single-supply microprocessor supervisory IC in an 8-pin SOT23 package, providing active-low push-pull reset output, independent watchdog timer with 1.6s timeout, adjustable 0.62V power-fail comparator (PFI/PFO), and manual reset input. It monitors +2.55V to +3.6V supply rails and guarantees valid reset down to VCC = 1.2V for critical µP power monitoring in white goods and telecom systems.

For engineers reviewing the MAX6705RKA+T datasheet, MAX6705RKA+T pinout, MAX6705RKA+T application, or MAX6705RKA+T equivalent, this device delivers precision voltage supervision, brownout immunity, and system-level fault detection without external timing components - key for embedded controllers and intelligent instrumentation requiring deterministic reset behavior under transient supply conditions.

Technical Context

The MAX6705RKA+T implements a dedicated reset generator with internal 140ms timeout delay and a separate watchdog circuit that asserts WDO low if WDI is not toggled within 1.6s (typ). Its PFI input connects to an external resistor divider to set custom power-fail thresholds, while PFO provides active-low open-drain or push-pull output synchronized to PFI crossing 0.62V.

It features guaranteed reset assertion down to VCC = 1.2V, immunity to short falling-VCC transients, and CMOS-compatible MR input with internal 50kΩ pullup. The RKA suffix denotes a 2.63V reset threshold (±3% over –40°C to +125°C), optimized for +2.5V–+3.3V systems.

Key Specifications

Pinout & Package

MAX6705RKA+T is housed in an 8-pin SOT23 package (package code K8+2), measuring 2.9mm × 1.6mm × 1.1mm, RoHS-compliant and lead-free (indicated by "+T" suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6705RKA-T, the +T version ensures RoHS compliance without performance trade-offs; versus MAX6706RKA+T, it provides native active-low reset compatible with most legacy µPs and simplifies level-shifting in mixed-voltage systems.

Availability

MAX6705RKA+T is available at Aetrix Electronics and suitable for intelligent instrumentation, white goods control, and telecommunications equipment requiring stable component supply across extended temperature ranges and strict environmental compliance.

Supply support for MAX6705RKA+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 industrial, communications, and computing applications, with emphasis on reliability and integration.

The MAX6701–MAX6708 family targets cost-sensitive, space-constrained µP supervision needs - delivering four core functions (reset, watchdog, power-fail warning, manual reset) in a single 8-pin SOT23, eliminating discrete solutions.

FAQ

What is the exact reset threshold voltage of MAX6705RKA+T and how is it specified?

The MAX6705RKA+T has a nominal reset threshold of 2.63V, with ±3% tolerance over the full operating temperature range of –40°C to +125°C. This value is guaranteed by production testing and corresponds to the "R" suffix in the part number. The threshold is internally trimmed and referenced to a stable bandgap, ensuring accuracy without external calibration. MAX6705RKA+T maintains this specification across its entire supply range (+2.55V to +3.6V) and load conditions.

Does MAX6705RKA+T support watchdog functionality, and how is it implemented?

Yes, MAX6705RKA+T includes a fully integrated watchdog timer with a typical timeout period of 1.6s. It monitors the WDI pin for edges; if no transition occurs within that window, WDO is asserted low. The watchdog cannot be disabled and clears automatically on any valid WDI edge, MR assertion, or VCC/RST_IN reset event. MAX6705RKA+T uses the A-version watchdog behavior: WDO deasserts immediately when the undervoltage condition ends or upon MR low, unlike non-A versions which require a WDI edge.

Can MAX6705RKA+T monitor voltages other than VCC, and how is that achieved?

MAX6705RKA+T does not include dual adjustable reset inputs (unlike MAX6701–MAX6703 variants), but it supports monitoring secondary supplies via its PFI pin. By connecting PFI to a resistor divider from the target voltage rail, users can set a custom trip point referenced to the internal 0.62V comparator threshold. For example, a 5V rail can be scaled to 0.62V using a 7.1:1 ratio. PFO then provides a corresponding active-low output, enabling early warning or cascaded reset generation - all without additional ICs. This capability is fully supported in MAX6705RKA+T.

What is the function of the PFO pin on MAX6705RKA+T, and what output type does it provide?

The PFO (Power-Fail Output) pin on MAX6705RKA+T is an active-low push-pull output that asserts when the voltage at PFI falls below the internal 0.62V reference. It drives logic-level signals directly - sinking up to 1.2mA at VCC ≥ 2.55V - and requires no external pullup. Unlike open-drain alternatives, PFO actively pulls low and high, simplifying interface to µP interrupt pins or secondary supervisors. This behavior is confirmed in the MAX6705(A) functional diagram and electrical characteristics table for MAX6705RKA+T.

Is MAX6705RKA+T pin-compatible with other members of the MAX6701–MAX6708 family?

Yes, MAX6705RKA+T shares identical 8-pin SOT23 pinout and footprint with all MAX6701–MAX6708 variants, including MAX6701RKA+T through MAX6708RKA+T. Pin assignments for MR, VCC, GND, PFI, PFO, WDI, RESET, and WDO are fixed across the family. However, functional differences exist: MAX6705RKA+T provides active-low push-pull RESET and independent WDO, whereas MAX6704 and MAX6708 lack WDO, and MAX6703/MAX6707 use open-drain RESET. Board reuse is possible only when matching required features.