A1122LLHLX-T Equivalent & Substitute Parts

Part Overview

The A1122LLHLX-T is an active unipolar Hall effect magnetic switch manufactured by Allegro MicroSystems, designed for digital switching applications requiring open drain output. This component operates across a wide supply voltage range of 3V to 24V with a maximum supply current of 4mA and output current capability of 25mA. The device is qualified to AEC-Q100 automotive standards and maintains operational capability across -40°C to 150°C. Substitute parts are identified when equivalent functional performance can be achieved through alternative Hall effect sensor designs with compatible electrical and mechanical specifications.

Key Parameters

Parameter	A1122LLHLX-T
Manufacturer	Allegro MicroSystems
Function	Unipolar Switch
Technology	Hall Effect
Output Type	Open Drain
Polarization	South Pole
Sensing Range	20mT Trip, 11mT Release
Voltage Supply	3V ~ 24V
Current Supply (Max)	4mA
Current Output (Max)	25mA
Operating Temperature	-40°C ~ 150°C
Package	SOT-23W
Mounting Type	Surface Mount
Product Status	Active
RoHS Status	ROHS3 Compliant
Grade	Automotive (AEC-Q100)

Substitute Part Grouping Explanation

Substitution eligibility for the A1122LLHLX-T is determined by the following critical parameters: Hall effect technology with open drain output, unipolar switch function, South Pole polarization, supply voltage compatibility within the 3V to 24V range, and surface mount packaging. The sensing range (trip and release thresholds) and output current capability are secondary selection criteria that may vary between substitutes while maintaining functional equivalence in typical applications.

Identified substitutes are grouped into two categories:

Category 1: ABLIC S-5731 Series (SOT-23-3 Package)

S-5731NNL2-M3T2U (North Pole polarization)
S-5731NSL1-M3T2U (South Pole polarization)
S-5731NSL2-M3T2U (South Pole polarization)

Category 2: Melexis US57xx Series (TSOT-23-3 Package)

US5782LSE-AAA-000-RE (North Pole polarization)
US5782ESE-AAA-000-RE (South Pole polarization)
US5881ESE-AAA-000-RE (North Pole polarization)

Parameter Comparison

Parameter	A1122LLHLX-T	S-5731NNL2-M3T2U	S-5731NSL1-M3T2U	S-5731NSL2-M3T2U	US5782LSE-AAA-000-RE	US5782ESE-AAA-000-RE	US5881ESE-AAA-000-RE
Manufacturer	Allegro MicroSystems	ABLIC Inc.	ABLIC Inc.	ABLIC Inc.	Melexis Technologies NV	Melexis Technologies NV	Melexis Technologies NV
Function	Unipolar Switch	Unipolar Switch	Unipolar Switch	Unipolar Switch	Unipolar Switch	Unipolar Switch	Unipolar Switch
Technology	Hall Effect	Hall Effect	Hall Effect	Hall Effect	Hall Effect	Hall Effect	Hall Effect
Output Type	Open Drain	Open Drain	Open Drain	Open Drain	Open Drain	Open Drain	Open Drain
Polarization	South Pole	North Pole	South Pole	South Pole	North Pole	South Pole	North Pole
Voltage Supply	3V ~ 24V	4.6V ~ 26V	4.6V ~ 26V	4.6V ~ 26V	4.6V ~ 24V	4.6V ~ 24V	4.6V ~ 24V
Current Supply (Max)	4mA	4mA	4mA	4mA	5mA	5mA	5mA
Current Output (Max)	25mA	20mA	20mA	20mA	50mA	50mA	50mA
Operating Temperature	-40°C ~ 150°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 150°C	-40°C ~ 85°C	-40°C ~ 85°C
Package	SOT-23W	SOT-23-3	SOT-23-3	SOT-23-3	TSOT-23-3	TSOT-23-3	TSOT-23-3
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Active	Active	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

All identified substitute parts maintain active product status and ROHS3 compliance, ensuring continued availability and environmental regulatory adherence. The A1122LLHLX-T operates across -40°C to 150°C; substitutes from the ABLIC S-5731 series are limited to -40°C to 85°C, while the Melexis US5782LSE-AAA-000-RE extends to -40°C to 150°C, matching the original specification. The Melexis US5782ESE-AAA-000-RE and US5881ESE-AAA-000-RE are rated to -40°C to 85°C.

For applications requiring the full -40°C to 150°C operating range, US5782LSE-AAA-000-RE is the appropriate selection among Melexis options. The ABLIC S-5731 series substitutes are suitable for applications with maximum operating temperatures not exceeding 85°C.

Polarization selection must align with magnetic field orientation in the application. South Pole sensing is provided by S-5731NSL1-M3T2U, S-5731NSL2-M3T2U, and US5782ESE-AAA-000-RE. North Pole sensing is provided by S-5731NNL2-M3T2U, US5782LSE-AAA-000-RE, and US5881ESE-AAA-000-RE.

Frequently Asked Questions (FAQ)

Q: Can the A1122LLHLX-T be directly replaced with S-5731 series parts?

A: Direct replacement requires verification of package compatibility. The A1122LLHLX-T uses SOT-23W packaging, while S-5731 series parts use SOT-23-3 packaging. Physical footprint and pin configuration must be confirmed for PCB compatibility. Electrical specifications are compatible for open drain Hall effect switching applications.

Q: What is the difference between SOT-23W and SOT-23-3 packages?

A: SOT-23W and SOT-23-3 are both surface mount packages with three leads, but SOT-23W has a wider body profile compared to standard SOT-23-3. Pin pitch and lead spacing may differ, requiring PCB layout verification before substitution.

Q: Are Melexis US57xx series parts suitable replacements for automotive applications?

A: Yes. Melexis US57xx series parts are ROHS3 compliant and maintain active product status. The US5782LSE-AAA-000-RE specifically matches the -40°C to 150°C operating temperature range of the A1122LLHLX-T, making it suitable for automotive thermal requirements.

Q: How do sensing range differences affect substitution?

A: Sensing range (trip and release thresholds) determines the magnetic field strength required to activate the switch. The A1122LLHLX-T requires 20mT trip and 11mT release. Substitute parts have different thresholds and must be selected based on the specific magnetic field strength present in the application. Threshold mismatch will result in functional failure.

Q: What is the significance of polarization (North Pole vs. South Pole)?

A: Polarization determines which magnetic pole orientation activates the sensor. South Pole sensors respond to south-facing magnetic fields, while North Pole sensors respond to north-facing fields. Application magnetic field orientation must match the selected part's polarization specification.

Q: Can I use a substitute with lower maximum output current?

A: The A1122LLHLX-T provides 25mA maximum output current. ABLIC S-5731 series substitutes provide 20mA. If the application load requires more than 20mA, S-5731 series parts are not suitable. Melexis US57xx series parts provide 50mA, exceeding the original specification.

Q: Are all substitute parts in stock?

A: Inventory availability varies. S-5731NNL2-M3T2U has 1596 units, S-5731NSL1-M3T2U has 1025 units, S-5731NSL2-M3T2U has 1708 units, US5782LSE-AAA-000-RE has 3713 units, US5782ESE-AAA-000-RE has 20430 units, and US5881ESE-AAA-000-RE has 83200 units available as new original stock.

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