Analog Devices Inc./Maxim Integrated MAX6735KASHD3+

Overview

MAX6735KASHD3+ from Maxim Integrated is a triple-voltage microprocessor supervisor IC with independent watchdog timer, push-pull reset output, manual reset input, and adjustable RSTIN threshold for monitoring voltages down to +0.63V. It monitors VCC1 (+2.925V nominal), VCC2 (+2.188V nominal), and RSTIN (626mV internal reference), features 210ms reset timeout, and operates across –40°C to +85°C - used in multivoltage telecom power sequencing and server board management.

For engineers reviewing the MAX6735KASHD3+ datasheet, MAX6735KASHD3+ pinout, MAX6735KASHD3+ application, or MAX6735KASHD3+ equivalent, key selection criteria include its dual fixed-threshold + adjustable third-supply monitoring capability, push-pull RST/WDO outputs eliminating external pullups, 14μA typical supply current at +3.6V, and SOT23-8 package compatibility with space-constrained embedded control designs.

Technical Context

The MAX6735KASHD3+ implements three independent voltage-monitoring comparators: one for VCC1 (2.925V threshold), one for VCC2 (2.188V threshold), and one high-impedance adjustable comparator on RSTIN referenced to a 626mV internal bandgap. Its reset logic asserts active-low RST when any monitored voltage falls below its threshold or MR is pulled low.

It integrates a dual-mode watchdog timer: 35s minimum startup delay after reset, then 1.12s minimum normal-mode timeout; WDI edge detection clears the timer, while WDO provides an independent active-low push-pull output. All timing and thresholds are factory-trimmed and specified over –40°C to +85°C.

Key Specifications

Pinout & Package

MAX6735KASHD3+ is housed in an 8-pin SOT23-8 package (JEDEC MO-178AA), footprint-compatible with standard SOT23-8 land patterns (Maxim land pattern 90-0176), with 0.65mm pitch and 1.6mm × 2.9mm body size.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6734KASHD3+, MAX6735KASHD3+ delivers direct-drive reset signaling and eliminates pullup components; versus TPS3808G33DBVR, it provides essential triple-supply coverage and manual reset - making it the sole fit for multivoltage systems requiring guaranteed coordinated reset timing.

Availability

MAX6735KASHD3+ is available at Aetrix Electronics and suitable for telecom power sequencing, server baseboard management, and industrial PLC controller designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6735KASHD3+ 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, computing, and communications markets, with expertise in power management and supervisory circuits.

The MAX6730–MAX6735 family was engineered specifically for multivoltage microprocessor systems requiring coordinated reset, watchdog safety, and minimal external components - targeting telecom infrastructure, servers, and ruggedized embedded controllers.

FAQ

What is the exact reset threshold voltage for VCC1 on MAX6735KASHD3+?

The MAX6735KASHD3+ has a factory-set VCC1 reset threshold of +2.925V (nominal), with guaranteed range +2.850V to +3.000V at falling edge. This value is defined by the "S" suffix in the part number and is trimmed during production for accuracy across temperature. The threshold remains stable with ±20ppm/°C tempco and includes 0.5% hysteresis relative to typical value.

Does MAX6735KASHD3+ support monitoring a third voltage higher than 626mV?

Yes, MAX6735KASHD3+ supports monitoring voltages above 626mV using the RSTIN pin. Connect a resistive voltage divider between the target supply and GND, with the midpoint fed to RSTIN. The external threshold is calculated as VEXT_TH = 626mV × (R1 + R2)/R2. MAX6735KASHD3+'s high-impedance RSTIN input (±25nA leakage) ensures minimal loading on the divider network.

What is the watchdog timeout behavior after power-on reset for MAX6735KASHD3+?

After power-on reset, MAX6735KASHD3+ enters a 35s minimum initial watchdog mode (tWD-L), allowing full system initialization before watchdog enforcement begins. Once the first valid WDI edge occurs, it transitions to the 1.12s minimum normal-mode timeout (tWD-S). This dual-mode architecture prevents false timeouts during boot while ensuring rapid fault detection during runtime.

Can MAX6735KASHD3+ operate with VCC1 or VCC2 below 1.0V?

Yes, MAX6735KASHD3+ guarantees valid reset assertion down to VCC1 or VCC2 = +0.8V, per Absolute Maximum Ratings and Electrical Characteristics. However, RSTIN operation requires VCC1 ≥ 0.8V (as RSTIN is powered from VCC1), and supply current specs (e.g., 14μA typ) apply only above +0.8V. Below +0.8V, functionality is not assured.

Is MAX6735KASHD3+ pin-compatible with other MAX673x devices in SOT23-8?

MAX6735KASHD3+ shares the same SOT23-8 pinout as MAX6734 variants (e.g., MAX6734KASHD3+), with identical pin assignments for RST, GND, WDO, VCC1, RSTIN, WDI, VCC2, and MR. However, it is not pin-compatible with SOT23-6 MAX6730–MAX6733 devices due to differing pin count and function mapping.