HMHA281R1 Optoisolator Transistor Output 3750Vrms Equivalent & Substitute Parts

Part Overview

The HMHA281R1 is a single-channel optoisolator with transistor output manufactured by onsemi, rated for 3750Vrms isolation voltage. This component is classified as obsolete, which necessitates identification of active equivalent and substitute parts for ongoing design support and procurement. The HMHA281R1 features a 4-Mini-Flat surface mount package with 50mA output current capability and operates across the temperature range of -55°C to 100°C.

Key Parameters

Parameter	Value
Manufacturer Part Number	HMHA281R1
Manufacturer	onsemi
Category	Optoisolators
Product Status	Obsolete
Number of Channels	1
Voltage - Isolation	3750Vrms
Current Transfer Ratio (Min)	50% @ 5mA
Current Transfer Ratio (Max)	600% @ 5mA
Rise / Fall Time (Typ)	3µs, 3µs
Input Type	DC
Output Type	Transistor
Voltage - Output (Max)	80V
Current - Output / Channel	50mA
Voltage - Forward (Vf) (Typ)	1.3V (Max)
Current - DC Forward (If) (Max)	50mA
Vce Saturation (Max)	400mV
Operating Temperature	-55°C ~ 100°C
Mounting Type	Surface Mount
Package / Case	4-SOIC (0.173", 4.40mm Width)
Moisture Sensitivity Level (MSL)	1 (Unlimited)
REACH Status	REACH Unaffected

Substitute Part Grouping Explanation

Substitution of the HMHA281R1 is determined by strict equivalence across the following critical parameters:

Electrical Parameters (Must Match):

Voltage - Isolation: 3750Vrms
Number of Channels: 1
Input Type: DC
Output Type: Transistor
Voltage - Output (Max): 80V
Current Transfer Ratio range: 50% to 600% @ 5mA
Rise / Fall Time: 3µs, 3µs
Vce Saturation (Max): 400mV

Mechanical Parameters (Must Match):

Mounting Type: Surface Mount
Package / Case: 4-SOIC (0.173", 4.40mm Width) or equivalent 4-Mini-Flat configuration

Allowable Variations:

Current - Output / Channel: May equal or exceed 50mA
Operating Temperature: May extend beyond -55°C to 100°C
Product Status: Active status preferred over obsolete
Packaging format: Tape & Reel acceptable for procurement flexibility
RoHS Compliance: ROHS3 Compliant acceptable

The substitute parts HMHA281R2, HMHA281R2V, HMHA281R4, and FODM121R2 meet these criteria with variations noted in the parameter comparison table.

Parameter Comparison

Parameter	HMHA281R1	HMHA281R2	HMHA281R2V	HMHA281R4	FODM121R2
Product Status	Obsolete	Active	Active	Active	Active
Number of Channels	1	1	1	1	1
Voltage - Isolation	3750Vrms	3750Vrms	3750Vrms	3750Vrms	3750Vrms
Current Transfer Ratio (Min)	50% @ 5mA	50% @ 5mA	50% @ 5mA	50% @ 5mA	50% @ 5mA
Current Transfer Ratio (Max)	600% @ 5mA	600% @ 5mA	600% @ 5mA	600% @ 5mA	600% @ 5mA
Rise / Fall Time (Typ)	3µs, 3µs	3µs, 3µs	3µs, 3µs	3µs, 3µs	3µs, 3µs
Input Type	DC	DC	DC	DC	DC
Output Type	Transistor	Transistor	Transistor	Transistor	Transistor
Voltage - Output (Max)	80V	80V	80V	80V	80V
Current - Output / Channel	50mA	50mA	50mA	50mA	80mA
Voltage - Forward (Vf) (Typ)	1.3V (Max)	1.3V (Max)	1.3V (Max)	1.3V (Max)	1.3V (Max)
Current - DC Forward (If) (Max)	50mA	50mA	50mA	50mA	50mA
Vce Saturation (Max)	400mV	400mV	400mV	400mV	400mV
Operating Temperature	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C	-40°C ~ 110°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	4-SOIC (0.173", 4.40mm Width)	4-SOIC (0.173", 4.40mm Width)	4-SOIC (0.173", 4.40mm Width)	4-SOIC (0.173", 4.40mm Width)	4-SMD, Gull Wing
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

Primary Substitutes (Parametric Equivalents):

HMHA281R2 and HMHA281R2V are direct parametric equivalents to the HMHA281R1. Both parts maintain identical electrical and mechanical specifications while offering active product status and ROHS3 compliance. These parts are preferred for new designs and ongoing production requiring the 4-SOIC package configuration. HMHA281R2V provides the same performance as HMHA281R2 with equivalent availability and compliance certifications.

Secondary Substitute (Parametric Equivalent):

HMHA281R4 is a parametric equivalent with active product status and ROHS3 compliance. This part maintains all critical electrical parameters and the 4-SOIC package footprint, making it suitable for direct replacement in existing designs.

Alternative Substitute (Different Package):

FODM121R2 provides electrical equivalence with a notable difference in output current capability (80mA versus 50mA) and package configuration (4-SMD, Gull Wing versus 4-SOIC). This part is suitable for applications where the higher output current and extended operating temperature range (-40°C to 110°C) provide design advantages. The different package requires PCB layout modification and is not a direct footprint replacement.

All substitute parts carry REACH Unaffected status and MSL 1 (Unlimited) moisture sensitivity rating, matching the environmental compliance profile of the original part.

Frequently Asked Questions (FAQ)

Q: Can HMHA281R2 directly replace HMHA281R1 without PCB modification?

A: Yes. HMHA281R2 maintains identical package specifications (4-SOIC, 0.173" width, 4.40mm) and all critical electrical parameters. No PCB layout changes are required for direct substitution.

Q: What is the difference between HMHA281R2 and HMHA281R2V?

A: Both parts are parametric equivalents with identical electrical specifications, operating temperature range, and package configuration. The designation difference reflects manufacturing or distribution variants with equivalent performance characteristics.

Q: Why is FODM121R2 listed as a substitute if the package is different?

A: FODM121R2 meets all electrical equivalence criteria (isolation voltage, current transfer ratio, output voltage, switching time) and offers enhanced output current capability (80mA). The 4-SMD, Gull Wing package requires PCB redesign but is suitable for applications where the higher current rating and extended temperature range provide functional benefits.

Q: Is HMHA281R4 suitable for production use?

A: Yes. HMHA281R4 is an active product with ROHS3 compliance and maintains all electrical and mechanical specifications of the HMHA281R1. It is suitable for both new designs and production replacement of obsolete inventory.

Q: What compliance certifications apply to all substitute parts?

A: All substitute parts carry REACH Unaffected status, MSL 1 (Unlimited) moisture sensitivity rating, and ROHS3 compliance. These

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