onsemi MAX809HTR

Overview

MAX809HTR from onsemi is a precision 3-pin microprocessor reset supervisor IC with active-low RESET output, designed to monitor VCC in digital systems and assert reset when supply voltage falls below 4.55 V (typical threshold). It delivers factory-trimmed 140–460 ms power-on reset timeout, operates from 1.2 V to 5.5 V, draws only 0.5 µA at 3.3 V, and supports industrial temperature range (−40°C to +105°C). It is used in embedded systems requiring reliable brownout detection and glitch-immune reset signaling.

For engineers reviewing the MAX809HTR datasheet, pinout, applications, or equivalent options, key selection considerations include its 4.55 V reset threshold, SOT-23-3 package, active-low push-pull output, transient immunity up to 100 mV/5 µs, and guaranteed RESET validity down to VCC = 1.0 V - critical for battery-powered and industrial control designs.

Technical Context

The MAX809HTR integrates an internal voltage detector, oscillator, and digital timeout counter to generate a precise, temperature-stable reset pulse upon power-up, power-down, or brownout. Its comparator features ±1.5% threshold accuracy over temperature and a low 30 ppm/°C temperature coefficient.

It uses a push-pull output stage capable of sinking ≥1.2 mA at VCC ≥ 2.1 V and sourcing ≥0.5 mA at VCC ≥ 1.6 V, ensuring robust interface with CMOS microcontrollers. The device rejects fast transients via internal hysteresis and timing filtering, eliminating false resets from sub-5 µs, 100 mV supply glitches.

Key Specifications

Pinout & Package

SOT-23-3 (Case 318), 2.90 mm × 1.30 mm × 1.00 mm body, Pb-free, RoHS compliant. Surface-mount package with gull-wing leads, optimized for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809LTRG and TPS3808G15DBVR, the MAX809HTR provides optimal balance of precision (4.55 V), ultra-low ICC (0.5 µA), and zero-component simplicity for fixed 5 V monitoring - making it ideal for cost-sensitive, high-volume industrial and medical devices where layout space and battery life are constrained.

Availability

MAX809HTR is available at Aetrix Electronics and suitable for industrial PLC controllers, smart energy meters, and portable medical diagnostics requiring stable component supply and long-term lifecycle support.

Supply support for MAX809HTR 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, and medical markets.

The MAX809 series belongs to onsemi's system supervision product line, engineered specifically for reliable, low-power reset generation in resource-constrained embedded systems operating across extended temperature ranges.

FAQ

What is the exact reset voltage threshold for MAX809HTR?

The MAX809HTR has a typical reset threshold of 4.55 V, with guaranteed min/max values of 4.43 V and 4.67 V over −40°C to +85°C, and 4.32 V to 4.78 V over −40°C to +105°C. This precision threshold ensures accurate monitoring of 5 V power rails without external trimming components.

Does MAX809HTR require external components to operate?

No, the MAX809HTR requires no external components. It integrates all necessary circuitry - voltage detector, oscillator, and timeout counter - into the SOT-23-3 package. A single 0.1 µF ceramic decoupling capacitor on VCC is recommended per datasheet, but not mandatory for basic functionality.

What is the power-on reset timeout duration for MAX809HTR?

The MAX809HTR features a factory-trimmed reset timeout of 140–460 ms. This range satisfies JEDEC JESD78-compliant minimum reset pulse widths for most 32-bit microcontrollers and FPGAs, ensuring reliable core initialization before code execution begins.

Can MAX809HTR operate with a 3.3 V supply?

Yes, the MAX809HTR operates across 1.2 V to 5.5 V, including 3.3 V nominal supplies. Its 4.55 V threshold makes it suitable for monitoring upstream 5 V rails that power 3.3 V regulators - not for direct 3.3 V rail supervision. For 3.3 V monitoring, consider MAX809STRG (2.93 V).

Is MAX809HTR pin-compatible with other MAX809 variants?

Yes, all MAX809 variants - including MAX809HTR, MAX809LTRG, and MAX809STRG - share identical SOT-23-3 pinout (GND, RESET, VCC) and active-low push-pull output architecture. Only the reset threshold and marking code differ, enabling drop-in replacement within the same voltage monitoring requirement.