LAA125STR Solid State Relay - Equivalent & Substitute Parts

Part Overview

The LAA125STR is an IXYS OptoMOS® solid state relay (SSR) configured as a SPST-NO (Single Pole Single Throw - Normally Open) switch. This surface mount component operates with dual Form A circuits in an 8-SMD package and is designed for AC and DC load switching applications up to 350V with a maximum load current of 170mA. The part is currently active in production and widely available in inventory, making it suitable for new designs and production applications requiring reliable solid state switching without mechanical contacts.

Equivalent and substitute parts are identified when they maintain compatibility across critical electrical and mechanical parameters, including load voltage range, circuit configuration, package type, and termination style, while accommodating minor variations in input voltage, load current capacity, and on-state resistance within acceptable application tolerances.

Substiute Parts

LAA125STR

IXYS Integrated Circuits DivisionIn Stock: 10150LAA125STR Datasheet

Current PartRFQ

AQW210EHAZ

Panasonic Electric WorksIn Stock: 3957AQW210EHAZ Datasheet

MFR RecommendedRFQ

LH1520AACTR

Vishay Semiconductor Opto DivisionIn Stock: 1336LH1520AACTR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the LAA125STR are qualified based on the following critical parameters that must remain constant or within acceptable engineering tolerances:

Fixed Parameters (Must Match Exactly):

• Circuit configuration: SPST-NO (1 Form A) x 2
• Output type: AC, DC capable
• Load voltage range: 0V ~ 350V
• Package type: 8-SMD (0.300", 7.62mm)
• Termination style: Gull Wing
• Mounting type: Surface Mount

Variable Parameters (Acceptable Tolerance Range):

• Input voltage: 1.14VDC to 1.26VDC (±5% tolerance acceptable)
• Load current: 110mA to 170mA (application dependent)
• On-state resistance: 16 Ohms to 25 Ohms (affects power dissipation)

The two qualified substitutes—AQW210EHAZ (Panasonic PhotoMOS™) and LH1520AACTR (Vishay LH1520)—maintain identical mechanical and electrical load specifications while exhibiting minor variations in input voltage requirements and current handling capacity. These variations are within acceptable ranges for most switching applications and do not compromise the fundamental switching function or load compatibility.

Parameter Comparison

Engineering Selection Recommendations

All three parts—LAA125STR, AQW210EHAZ, and LH1520AACTR—are active production components with ROHS3 compliance and REACH unaffected status, qualifying them for use in regulated applications and new designs.

LAA125STR (Primary Part): Offers the highest load current capacity at 170mA with the lowest on-state resistance at 16 Ohms, resulting in minimal power dissipation. Recommended for applications requiring maximum current handling or where thermal management is a design constraint.

AQW210EHAZ (Panasonic Substitute): Provides the lowest input voltage requirement at 1.14VDC, making it suitable for applications with limited input signal voltage margins. Load current capacity is reduced to 120mA with on-state resistance of 25 Ohms. Moisture sensitivity level is not applicable, which may be advantageous in certain environmental conditions.

LH1520AACTR (Vishay Substitute): Operates at 1.26VDC input with 110mA load current capacity and 20 Ohms on-state resistance. Maintains MSL Level 1 (Unlimited) rating consistent with the primary part. Represents a middle-ground option between the IXYS and Panasonic alternatives.

Selection between these parts depends on application-specific requirements for input voltage compatibility, load current demands, and thermal dissipation tolerance. All three maintain identical load voltage range (0V ~ 350V) and package compatibility, ensuring direct PCB layout compatibility.

Frequently Asked Questions (FAQ)

Q: Can AQW210EHAZ be used as a direct replacement for LAA125STR in all applications?

A: AQW210EHAZ is mechanically and electrically compatible for applications requiring load currents up to 120mA. Applications demanding the full 170mA load current capacity of the LAA125STR require verification that the reduced current rating of the substitute is acceptable. The higher on-state resistance (25 Ohms vs. 16 Ohms) results in increased power dissipation, which must be evaluated against thermal design margins.

Q: What are the input voltage compatibility considerations?

A: The three parts operate at slightly different input voltages: LAA125STR at 1.2VDC, AQW210EHAZ at 1.14VDC, and LH1520AACTR at 1.26VDC. These variations are within typical control circuit tolerances. Applications with strict input voltage regulation or marginal signal levels should confirm compatibility with the specific substitute part's input voltage specification.

Q: Are all three parts suitable for both AC and DC load switching?

A: Yes. All three parts are rated for AC and DC output operation across the 0V ~ 350V load voltage range. No restrictions apply to load type selection based on the part substitution.

Q: Do package and termination differences exist between these parts?

A: No. All three parts use identical 8-SMD (0.300", 7.62mm) packages with Gull Wing termination. PCB footprints and reflow soldering profiles are directly compatible without modification.

Q: Which part should be selected for new designs?

A: For new designs without existing inventory constraints, the LAA125STR provides the highest performance margin with maximum load current (170mA) and lowest on-state resistance (16 Ohms). Substitute parts are appropriate when LAA125STR availability is limited or when application load current requirements are below 120mA.

Q: Are there compliance or certification differences between the three parts?

A: All three parts are ROHS3 compliant and REACH unaffected. No regulatory or certification barriers exist to substitution. Moisture sensitivity levels differ slightly (LAA125STR and LH1520AACTR are MSL Level 1 Unlimited; AQW210EHAZ is Not Applicable), which may influence storage and handling procedures but does not affect electrical performance or application suitability.