MAX809STR Equivalent & Substitute Parts

Part Overview

The MAX809STR is a single-channel power supply supervisor IC in SOT-23-3 surface mount packaging, designed for simple reset and power-on reset applications. This part is classified as obsolete, which necessitates identification of active equivalent and substitute components for new designs and ongoing production support. The MAX809STR provides push-pull totem pole output with active low reset control and a 140ms minimum reset timeout, operating across the -40°C to 105°C temperature range.

Key Parameters

Parameter	Value
Manufacturer Part Number	MAX809STR
Manufacturer	onsemi
Category	Power Management (PMIC)
Package / Case	TO-236-3, SC-59, SOT-23-3
Type	Simple Reset/Power-On Reset
Number of Voltages Monitored	1
Voltage - Threshold	2.93V
Output	Push-Pull, Totem Pole
Reset	Active Low
Reset Timeout	140ms Minimum
Operating Temperature	-40°C ~ 105°C (TJ)
Mounting Type	Surface Mount
RoHS Status	RoHS non-compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the MAX809STR is determined by the following critical parameters:

Voltage Threshold (2.93V): The monitoring threshold must match or be functionally equivalent for the application circuit
Output Configuration (Push-Pull, Totem Pole): The output stage topology must be identical
Reset Logic (Active Low): The reset polarity must remain active low
Reset Timeout (140ms Minimum): The timeout duration must meet or exceed the original specification
Package (SOT-23-3): Physical form factor must be identical for PCB compatibility
Operating Temperature Range: Must support the required thermal envelope
Single Channel Monitoring: Functional requirement for single voltage supervision

Substitute parts are grouped into two categories:

Direct Substitutes maintain all critical electrical and mechanical parameters with the MAX809STR, differing primarily in product status (active vs. obsolete) and RoHS compliance.

Similar Substitutes maintain the core functional parameters (voltage threshold, output type, reset logic, package) but may vary in reset timeout duration or operating temperature range. These parts are suitable when application requirements permit parameter variation within specified tolerances.

Parameter Comparison

Part Number	Manufacturer	Voltage Threshold	Output Type	Reset Logic	Reset Timeout (Min)	Operating Temp	Package	Product Status	RoHS Status
MAX809STR	onsemi	2.93V	Push-Pull, Totem Pole	Active Low	140ms	-40°C ~ 105°C	SOT-23-3	Obsolete	RoHS non-compliant
MAX809STRG	onsemi	2.93V	Push-Pull, Totem Pole	Active Low	140ms	-40°C ~ 105°C	SOT-23-3	Active	ROHS3 Compliant
TPS3809L30DBVR	Texas Instruments	2.64V	Push-Pull, Totem Pole	Active Low	120ms	-40°C ~ 85°C	SOT-23-3	Active	ROHS3 Compliant
ADM809-5SARTZ-RL7	Analog Devices Inc.	2.93V	Push-Pull, Totem Pole	Active Low	30ms	-40°C ~ 150°C	SOT-23-3	Active	ROHS3 Compliant
LM809M3-2.93/NOPB	Texas Instruments	2.93V	Push-Pull, Totem Pole	Active Low	140ms	-40°C ~ 105°C	SOT-23-3	Active	ROHS3 Compliant
LM809M3X-2.93/NOPB	Texas Instruments	2.93V	Push-Pull, Totem Pole	Active Low	140ms	-40°C ~ 105°C	SOT-23-3	Active	ROHS3 Compliant
MAX6326UR29+T	Analog Devices Inc./Maxim Integrated	2.93V	Push-Pull, Totem Pole	Active Low	100ms	-40°C ~ 85°C	SOT-23-3	Active	ROHS3 Compliant
MAX809SEUR+	Analog Devices Inc./Maxim Integrated	2.93V	Push-Pull, Totem Pole	Active Low	140ms	-40°C ~ 105°C	SOT-23-3	Active	ROHS3 Compliant
MAX809SEUR+T	Analog Devices Inc./Maxim Integrated	2.93V	Push-Pull, Totem Pole	Active Low	140ms	-40°C ~ 105°C	SOT-23-3	Active	ROHS3 Compliant
MAX809SEUR+T10	Analog Devices Inc./Maxim Integrated	2.93V	Push-Pull, Totem Pole	Active Low	140ms	-40°C ~ 105°C	SOT-23-3	Active	ROHS3 Compliant
MCP809M3-2.93/NOPB	National Semiconductor	2.93V	Push-Pull, Totem Pole	Active Low	140ms	-40°C ~ 105°C	SOT-23-3	Active	Not specified

Engineering Selection Recommendations

Primary Recommendation for Direct Replacement:

MAX809STRG (onsemi) provides the most direct substitution path. This part maintains identical electrical specifications (2.93V threshold, 140ms reset timeout, -40°C to 105°C operating range) and identical package configuration. The primary advantage is active product status with ROHS3 compliance, addressing the obsolescence and regulatory compliance limitations of the original MAX809STR.

Alternative Direct Substitutes:

LM809M3-2.93/NOPB and LM809M3X-2.93/NOPB (Texas Instruments) are functionally equivalent with matching voltage threshold, reset timeout, and operating temperature specifications. Both are active products with ROHS3 compliance and represent established alternatives from a major semiconductor manufacturer.

MAX809SEUR+T and MAX809SEUR+T10 (Analog Devices Inc./Maxim Integrated) maintain complete parameter equivalence with the original part and offer high inventory availability (107,600 and 869 units respectively). Both are active products with ROHS3 compliance.

Conditional Substitutes:

TPS3809L30DBVR (Texas Instruments) is suitable for applications where the operating temperature range can be reduced to -40°C to 85°C and reset timeout can be shortened to 120ms. The voltage threshold differs at 2.64V, requiring circuit validation.

ADM809-5SARTZ-RL7 (Analog Devices Inc.) maintains the 2.93V threshold but features a significantly shorter 30ms reset timeout and extended operating temperature to 150°C. Selection requires confirmation that the shorter timeout meets application requirements.

MAX6326UR29+T (Analog Devices Inc./Maxim Integrated) matches the voltage threshold but operates to 85°C maximum with 100ms reset timeout. Suitable for temperature-constrained applications.

MCP809M3-2.93/NOPB (National Semiconductor) provides parameter equivalence but lacks specified RoHS status documentation.

Frequently Asked Questions (FAQ)

Q: Can I directly replace MAX809STR with MAX809STRG?

A: Yes. MAX809STRG is the direct active equivalent with identical electrical and mechanical specifications. The primary differences are product status (active vs. obsolete) and RoHS compliance (ROHS3 vs. non-compliant).

Q: What is the key difference between LM809M3-2.93/NOPB and LM809M3X-2.93/NOPB?

A: Both parts are functionally identical in electrical specifications. The difference lies in packaging designation and inventory availability. LM809M3X-2.93/NOPB has significantly higher stock (35,300 units vs. 4,379 units).

Q: Can I use TPS3809L30DBVR as a substitute?

A: TPS3809L30DBVR is functionally compatible if your application permits a reduced operating temperature range (-40°C to 85°C instead of 105°C), shorter reset timeout (120ms instead of 140ms), and different voltage threshold (2.64V instead of 2.93V). Circuit validation is required.

Q: What does "Push-Pull, Totem Pole" output mean?

A: This output configuration provides both high-side and low-side drive capability, allowing the supervisor to actively pull the reset signal high or low. All listed substitutes maintain this output topology.

Q: Are all substitute parts available in the same SOT-23-3 package?

A: Yes. All listed substitute parts use the SOT-23-3 (TO-236-3, SC-59) package, ensuring PCB footprint compatibility with the original MAX809STR design.

Q: Which substitute offers the best long-term availability?

A: MAX809SEUR+T (Analog Devices Inc./Maxim Integrated) offers the highest inventory level at 107,600 units with active product status and ROHS3 compliance, providing strong long-term supply assurance.

Q: What is the significance of the 2.93V voltage threshold?

A: The 2.93V threshold determines the supply voltage level at which the supervisor triggers a reset signal. Substitutes must maintain this threshold for circuit compatibility, or the application circuit must be re-evaluated for alternative threshold values.

Q: Do all substitutes have the same reset timeout specification?

A: No. Reset timeout varies across substitutes (30ms to 140ms minimum). The original MAX809STR specifies 140ms minimum. Substitutes with shorter timeouts (ADM809-5SARTZ-RL7 at 30ms, TPS3809L30DBVR at 120ms) require application validation to confirm compatibility.

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