SIR-320ST3FF Infrared Emitter - Equivalent & Substitute Parts

Part Overview

The SIR-320ST3FF is a 940nm infrared emitter manufactured by Rohm Semiconductor, designed for through-hole T-1 package applications requiring 75mA forward current operation. This component is classified as obsolete, necessitating identification of functionally equivalent alternatives for ongoing system support and new design implementations. Substitute parts must maintain compatibility across wavelength, forward current rating, forward voltage, viewing angle, and thermal operating range parameters.

Substiute Parts

SIR-320ST3FF

Rohm SemiconductorIn Stock: 1156SIR-320ST3FF Datasheet

Current PartRFQ

SIR-34ST3F

Rohm SemiconductorIn Stock: 3690SIR-34ST3F Datasheet

MFR RecommendedRFQ

LTE-3271B

Lite-On Inc.In Stock: 1171LTE-3271B Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SIR-320ST3FF are evaluated based on the following critical parameters that determine functional equivalence:

• Wavelength: 940nm operation for spectral compatibility
• Forward Current Rating (If Max): Minimum 75mA to support original circuit current requirements
• Forward Voltage (Vf): Typical range 1.2V to 1.3V for circuit bias compatibility
• Radiant Intensity (Ie): Optical output performance at specified current levels
• Viewing Angle: Angular emission characteristics for optical system integration
• Operating Temperature Range: Thermal envelope compatibility (-25°C minimum to 85°C maximum)
• Mounting Type & Package: Through-hole T-1 or equivalent form factor
• Compliance Status: RoHS3 compliance and active or obsolete product status

Two substitute parts meet these criteria with documented compatibility:

SIR-34ST3F (Rohm Semiconductor, MFR Recommended): Manufacturer-designated substitute with enhanced current rating (100mA) and forward voltage (1.3V). Wavelength shifted to 950nm with increased viewing angle (54°). Obsolete status matches original part lifecycle.

LTE-3271B (Lite-On Inc., Similar): Active product with 940nm wavelength matching, 100mA current rating, and extended lower operating temperature (-40°C). Radial package form factor represents mechanical variation while maintaining through-hole mounting.

Parameter Comparison

Engineering Selection Recommendations

SIR-34ST3F Selection Criteria: Choose this Rohm Semiconductor substitute when maintaining manufacturer continuity and identical T-1 package form factor is required. This part is manufacturer-recommended and provides higher current capacity (100mA vs 75mA) with compatible forward voltage (1.3V vs 1.2V). The 950nm wavelength represents a 10nm shift from the original 940nm specification. Wider viewing angle (54° vs 36°) increases optical coverage. Both parts share obsolete status and ROHS3 compliance.

LTE-3271B Selection Criteria: Choose this Lite-On Inc. substitute when active product status and extended lower temperature operation (-40°C vs -25°C) are required. This part maintains exact 940nm wavelength matching and provides 100mA current capacity. The radial package form factor differs mechanically from T-1 but maintains through-hole mounting compatibility. Active product status ensures continued availability. ROHS3 compliance is maintained.

Compliance Basis: Both substitutes maintain ROHS3 compliance and EAR99 ECCN classification matching the original part. Selection between substitutes depends on product lifecycle requirements (obsolete vs active status) and mechanical form factor constraints (T-1 vs radial package).

Frequently Asked Questions (FAQ)

Q: Can SIR-34ST3F directly replace SIR-320ST3FF in existing designs?

A: SIR-34ST3F is manufacturer-recommended for substitution. The 10nm wavelength shift (950nm vs 940nm) and increased viewing angle (54° vs 36°) require verification that the optical system accepts these parameter variations. Forward voltage increase (1.3V vs 1.2V) and current rating increase (100mA vs 75mA) are compatible with circuits designed for the original part.

Q: What is the impact of the radial package form factor in LTE-3271B?

A: LTE-3271B uses radial package geometry instead of T-1 axial leads. Both are through-hole mounting types. PCB layout and mechanical clearance must accommodate the different lead configuration. Electrical performance remains compatible with the original circuit requirements.

Q: Does the 940nm wavelength of LTE-3271B provide exact spectral matching?

A: Yes. LTE-3271B operates at 940nm, identical to the SIR-320ST3FF. This eliminates wavelength-dependent system adjustments required when using the 950nm SIR-34ST3F substitute.

Q: Are both substitutes suitable for new designs?

A: SIR-34ST3F carries obsolete status, matching the original part lifecycle. LTE-3271B is active product status, making it suitable for new designs requiring long-term component availability. Compliance certifications (ROHS3, EAR99) are equivalent across all three parts.

Q: What forward current should be used when substituting with higher-rated parts?

A: Circuit design should maintain the original forward current specification (75mA or lower). Both substitutes support this current level. The higher maximum ratings (100mA) provide design margin but do not require increased operating current.