Analog Devices Inc./Maxim Integrated MAX6705SKA

Overview

MAX6705SKA from Maxim Integrated is a low-voltage, 8-pin SOT23 microprocessor supervisory circuit that monitors a single supply voltage, provides an independent adjustable power-fail comparator (PFI/PFO), manual reset input (MR), and a watchdog timer with independent WDO output. It asserts active-low push-pull RESET during power-up, brownout, or manual trigger, supports VCC down to 1V, and delivers 140ms reset timeout. It is used in automotive control modules requiring reliable µP reset and early power-fail warning.

For engineers reviewing the MAX6705SKA datasheet, MAX6705SKA pinout, MAX6705SKA application, or MAX6705SKA equivalent, key selection criteria include its 1.6s watchdog timeout, 0.62V PFI threshold, guaranteed reset validity to VCC = 1V, active-low push-pull RESET output, and compatibility with +5.0V/+3.3V/+3.0V/+2.5V supply monitoring.

Technical Context

The MAX6705SKA integrates a precision voltage monitor for VCC with factory-trimmed reset threshold (suffix 'S' = 2.93V), a dedicated 0.62V reference-based power-fail comparator with externally adjustable trip point via PFI, and a 1.6s watchdog timer cleared by WDI edges or reset assertion. Its RESET output is active-low push-pull, asserted on VCC drop below threshold, MR low, or watchdog timeout - and held for 140ms after recovery.

Unlike MAX6704/MAX6708, it includes independent WDO (active-low open-drain or push-pull) that latches low on watchdog overflow or undervoltage; unlike MAX6701–MAX6703 variants, it lacks dual adjustable RST_IN inputs and monitors only VCC. The 'A' version ensures WDO deasserts immediately upon VCC recovery without timeout delay.

Key Specifications

Pinout & Package

MAX6705SKA is housed in an 8-pin SOT23-8 package (JEDEC MO-178 BA), measuring 3.00mm × 1.75mm × 1.30mm, with gull-wing leads and lead-free option available (+T suffix). Pin 1 marked by dot; pinout matches MAX6705(A)/MAX6706(A)/MAX6707(A) configuration.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6705TKA, the MAX6705SKA offers tighter reset threshold alignment for marginal 3.3V rails, while TPS3808G33DBVR sacrifices PFI/PFO and WDO functionality for reduced footprint and cost - making MAX6705SKA the optimal choice when early power-fail detection and watchdog autonomy are required.

Availability

MAX6705SKA is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC I/O modules, smart energy meters, and medical infusion pump controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6705SKA 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 demanding industrial, automotive, and communications applications, emphasizing reliability, integration, and thermal robustness.

The MAX6701–MAX6708 family was engineered specifically for microprocessor supervision in space-constrained, high-reliability systems - delivering integrated reset, watchdog, power-fail warning, and manual reset in ultra-small SOT23 packages.

FAQ

What is the reset threshold voltage for MAX6705SKA?

The MAX6705SKA has a factory-trimmed VCC reset threshold of 2.93V (typical), specified over -40°C to +125°C. This value corresponds to the 'S' suffix in the part number and is optimized for reliable supervision of +3.3V microprocessor supplies, with ±3% tolerance across temperature and voltage. The threshold is internally generated and does not require external resistors.

Does MAX6705SKA support power-fail warning for secondary supply rails?

Yes, MAX6705SKA supports power-fail warning via its PFI/PFO comparator. The PFI pin connects to an external resistor divider from the secondary rail (e.g., 5V I/O supply), referenced to the internal 0.62V threshold. When the divided voltage falls below 0.62V, PFO asserts low - enabling early warning up to 10ms before regulator dropout. Hysteresis of 6mV prevents chatter near trip point.

What is the function of the WDO pin on MAX6705SKA?

The WDO pin on MAX6705SKA is an active-low watchdog output that asserts when the internal 1.6s timer expires due to missing WDI edges, or when VCC drops below the 2.93V reset threshold. In the 'A' version (as indicated by 'KA' in MAX6705SKA), WDO deasserts immediately upon VCC recovery - unlike non-A versions which require a WDI edge. WDO operates independently of the RESET pin.

Can MAX6705SKA operate with supply voltages below 3.3V?

Yes, MAX6705SKA operates from 1.2V to 5.5V and guarantees valid RESET output down to VCC = 1V. Its internal comparators and timer remain functional across this range, and the 2.93V reset threshold is maintained with ±3% accuracy even at minimum VCC. This makes MAX6705SKA suitable for battery-powered systems experiencing deep brownout conditions.

How does the manual reset (MR) input interact with the watchdog and reset functions in MAX6705SKA?

In MAX6705SKA, pulling MR low forces immediate RESET assertion for the full 140ms timeout period, regardless of VCC level or watchdog state. MR also clears the watchdog timer - so asserting MR deasserts WDO in the 'A' version. MR has internal 50kΩ pullup, is CMOS-compatible, and rejects <100ns glitches. It can be driven by pushbutton, logic line, or WDO (for watchdog-triggered reset pulses).