Analog Devices Inc./Maxim Integrated MAX6451UT46L+

Overview

MAX6451UT46L+ from Maxim Integrated is a dual-supply microprocessor reset supervisor IC with one fixed-threshold (4.625V) and one adjustable-threshold (0.63V reference) voltage monitor, extended manual reset setup period (6.72s), push-pull active-low RESET output, and operation over –40°C to +85°C. It prevents spurious resets in set-top boxes and industrial equipment during power transients or brief switch closures.

For engineers reviewing the MAX6451UT46L+ datasheet, MAX6451UT46L+ pinout, MAX6451UT46L+ application, or MAX6451UT46L+ equivalent, key selection considerations include its dual manual reset architecture (MR1 extended + MR2 immediate), 4.625V VCC threshold tolerance (±0.125V), 6.72s tMR timing, RSTIN-adjustable monitoring down to 0.63V, and guaranteed RESET assertion down to VCC = 1.0V.

Technical Context

The MAX6451UT46L+ integrates two independent reset comparators: one factory-trimmed for VCC at 4.625V (±0.125V), and another high-impedance RSTIN input referenced to 0.63V, enabling external resistor-divider configuration for custom supply monitoring. Its internal timing circuitry enforces strict 6.72s low assertion on MR1 before generating a 210ms typical reset pulse.

MR2 provides an immediate-reset function triggered by a rising edge, debounced for 210ms to suppress false assertions during card insertion/removal events. The push-pull RESET output guarantees valid logic states across the full 1.0V–5.5V VCC range, with VOL ≤ 0.3V at ISINK = 50µA and VOH ≥ 0.8×VCC at ISOURCE = 200µA.

Key Specifications

Pinout & Package

MAX6451UT46L+ is housed in a 6-pin SOT23 package (U6+1 outline), with 1.9mm × 2.9mm footprint and 0.95mm height, suitable for space-constrained consumer and industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6451UT46L+, MAX6452UT46L+ offers identical supervision capability but requires external biasing for RESET, while TPS3808G33DBVR reduces complexity and current draw at the expense of flexibility in multi-rail and dual-reset-mode applications.

Availability

MAX6451UT46L+ is available at Aetrix Electronics and suitable for set-top boxes, DVD players, industrial PLC modules, cable modems, and automotive infotainment head units requiring stable component supply across extended temperature ranges and long-term production cycles.

Supply support for MAX6451UT46L+ 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, automotive, and communications applications.

The MAX6443–MAX6452 family delivers highly reliable, low-power microprocessor supervisory circuits with extended manual reset timing and dual-threshold monitoring for consumer, industrial, and automotive systems.

FAQ

What is the exact reset threshold voltage for MAX6451UT46L+ on the VCC pin?

The MAX6451UT46L+ has a factory-set VCC reset threshold of 4.625V, with a guaranteed tolerance of ±0.125V (4.50V to 4.75V) over the full –40°C to +85°C temperature range. This value is confirmed in the Electrical Characteristics table under "VCC Reset Threshold" for suffix "46", and applies specifically to the MAX6451UT46L+ variant.

How does the MR2 pin function on MAX6451UT46L+ compared to MR1?

On the MAX6451UT46L+, MR1 is an extended-setup manual reset input requiring ≥6.72s low assertion to trigger RESET, while MR2 is an immediate-reset input activated by a rising edge. MR2 is debounced for 210ms to prevent false triggers during contact bounce, making it ideal for smart-card detect or service-mode buttons where fast response is needed without spurious pulses.

Can MAX6451UT46L+ monitor a 1.2V core supply, and how is that configured?

Yes, MAX6451UT46L+ can monitor a 1.2V core supply using its RSTIN pin. Connect the 1.2V rail to RSTIN through an external resistor divider such that the voltage at RSTIN equals 0.63V when the monitored supply reaches 1.2V. For example, use R2 = 250kΩ and R1 = 226kΩ (R1 = R2 × (1.2V / 0.63V − 1)), ensuring VMON-TH = 1.2V per the datasheet formula.

What is the minimum VCC voltage at which MAX6451UT46L+ guarantees valid RESET output logic?

The MAX6451UT46L+ guarantees valid RESET output logic down to VCC = 1.0V. Below this, current-sinking capability degrades rapidly. The device specifies VOL ≤ 0.3V at ISINK = 50µA for VCC ≥ 1.0V, and VOH ≥ 0.8×VCC for VCC ≥ 1.8V, ensuring compatibility with µPs operating across wide input voltage ranges.

Is MAX6451UT46L+ pin-compatible with other devices in the MAX6443–MAX6452 family?

MAX6451UT46L+ is pin-compatible with MAX6452UT46L+ (same 6-pin SOT23 layout), but not with 4-pin SOT143 (e.g., MAX6444) or 5-pin SOT23 (e.g., MAX6447) variants. Within the 6-pin group, pin functions match exactly: GND, VCC, MR1, MR2, RSTIN, RESET - enabling direct substitution where push-pull vs. open-drain output requirements align.