Analog Devices Inc./Maxim Integrated MAX6708RKA+

Overview

MAX6708RKA+ from Maxim Integrated is a low-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, providing dual active-low/high push-pull reset outputs, power-fail monitoring with 0.62V threshold input (PFI), and independent power-fail output (PFO). It operates across 2.1V–2.75V supply range, guarantees valid reset down to VCC = 1V, and delivers 140ms reset timeout delay - used for reliable power-up sequencing and brownout protection in embedded controllers and industrial systems.

For engineers reviewing the MAX6708RKA+ datasheet, MAX6708RKA+ pinout, MAX6708RKA+ application, or MAX6708RKA+ equivalent, this page delivers verified functional identity, confirmed pin roles, exact reset timing behavior, PFI/PFO comparator specifications, and validated alternative options - all aligned to the MAX6708 variant without watchdog timer functionality.

Technical Context

The MAX6708RKA+ implements a dual-stage reset generator with complementary outputs: RESET (active-low) and RESET (active-high), both push-pull, asserted when VCC falls below its 2.32V threshold (R-suffix), PFI drops below 0.62V, or MR is pulled low. Unlike MAX6701–MAX6707 variants, it omits the watchdog timer and WDI/WDO circuitry entirely - eliminating watchdog-related timing dependencies and simplifying system-level reset coordination.

Its power-fail comparator features externally accessible PFI and PFO pins, enabling early warning of supply degradation via resistor-divider networks; hysteresis is 6mV, leakage current is ±200nA over –40°C to +125°C, and PFI-to-PFO propagation delay is 1µs. The device supports multivoltage supervision by configuring PFI as secondary reset input, while maintaining guaranteed reset assertion down to VCC = 1V.

Key Specifications

Pinout & Package

MAX6708RKA+ uses an 8-pin SOT23-8 package (JEDEC MO-178 BA), 2.80mm × 2.90mm footprint, 1.45mm height, with gull-wing leads and coplanarity ≤ 0.1mm. Pin 1 marked by dot; lead finish is lead-free (RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6704RKA+, MAX6708RKA+ removes watchdog circuitry to reduce layout overhead and eliminate false resets from WDI noise; versus TPS3808G33DBVR, it adds PFI/PFO monitoring, dual reset polarity, and lower operating voltage - making it optimal for 2.5V systems requiring early power-fail response and hardware-level redundancy.

Availability

MAX6708RKA+ is available at Aetrix Electronics and suitable for industrial PLC controllers, smart energy meters, automotive body control modules, and medical diagnostic handhelds requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6708RKA+ 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 industrial, automotive, and communications applications - emphasizing high reliability, small form factor, and extended temperature operation.

The MAX6701–MAX6708 family was engineered for multivoltage microprocessor supervision in space-constrained, mission-critical systems - delivering integrated reset, power-fail warning, and manual reset in sub-3mm² packages with guaranteed performance from –40°C to +125°C.

FAQ

What is the reset threshold voltage for MAX6708RKA+?

The MAX6708RKA+ has a nominal reset threshold of 2.32V (R-suffix), with ±3% tolerance over –40°C to +125°C. This value is factory-trimmed and specified in the Electrical Characteristics table under "VCC Reset Threshold (VCC falling)". The threshold applies to the VCC pin and determines when the device asserts RESET outputs during power-down or brownout conditions.

Does MAX6708RKA+ include a watchdog timer function?

No, MAX6708RKA+ does not include a watchdog timer. As explicitly stated in the datasheet: "The MAX6708 is the same as the MAX6704 but without the watchdog timer function." It lacks WDI and WDO pins (pin 6 is N.C.), and contains no internal watchdog circuitry - distinguishing it from MAX6701–MAX6707 variants.

What are the functions of the two RESET pins on MAX6708RKA+?

Pin 7 is the active-high RESET output (push-pull), and pin 8 is the active-low RESET output (push-pull). Both are asserted simultaneously when VCC falls below 2.32V, MR is pulled low, or PFI drops below 0.62V. They remain asserted for the full 140ms timeout period after the fault clears - enabling direct interface to µPs with either reset polarity requirement.

Can MAX6708RKA+ monitor a 3.3V supply using the PFI input?

Yes, MAX6708RKA+ can monitor a 3.3V supply using PFI by connecting it through an external resistor divider. With a 0.62V internal reference, a divider ratio of R1/R2 ≈ 4.35 (e.g., 435kΩ/100kΩ) sets the trip point at 3.3V. The PFI input draws only ±200nA, allowing high-value resistors to minimize loading and power consumption.

What is the purpose of the N.C. pin on MAX6708RKA+?

Pin 6 on MAX6708RKA+ is designated N.C. (No Connection) - it is not internally bonded and carries no electrical function. It must be left unconnected on the PCB; no routing, termination, or grounding is required. This pin position corresponds to WDI on watchdog-enabled variants (e.g., MAX6705), but is unused in MAX6708RKA+.