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HMA121 Optoisolator Equivalent & Substitute Parts
Part Overview
The HMA121 is a 3750Vrms optoisolator with transistor output manufactured by onsemi in a 4-SMD package. This component is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The HMA121 provides single-channel isolation suitable for DC input applications requiring high voltage isolation with moderate current output capability.
Substiute Parts
Key Parameters
| Parameter | Value |
|---|---|
| Voltage - Isolation | 3750Vrms |
| Number of Channels | 1 |
| Output Type | Transistor |
| Current Transfer Ratio (Min) | 50% @ 5mA |
| Current Transfer Ratio (Max) | 600% @ 5mA |
| Voltage - Output (Max) | 80V |
| Current - Output / Channel | 80mA |
| Vce Saturation (Max) | 400mV |
| Operating Temperature | -40°C ~ 100°C |
| Mounting Type | Surface Mount |
| Input Type | DC |
Substitute Part Grouping Explanation
Substitution for the HMA121 is determined by strict equivalence across the following critical parameters:
- Voltage isolation rating: 3750Vrms (mandatory match)
- Output type: Transistor (mandatory match)
- Number of channels: 1 (mandatory match)
- Input type: DC (mandatory match)
- Maximum output voltage: 80V (mandatory match)
- Current transfer ratio range: Must encompass or exceed the HMA121 range (50% to 600% @ 5mA)
- Mounting type: Surface Mount (mandatory match)
- Vce saturation: Lower values indicate improved performance
- Operating temperature range: Must support the application's thermal requirements
Substitute parts are grouped into two categories: direct equivalents (identical electrical and mechanical specifications) and similar parts (equivalent electrical performance with package variations).
Parameter Comparison
| Part Number | Manufacturer | Voltage Isolation | CTR Min @ 5mA | CTR Max @ 5mA | Output Current | Vce Sat (Max) | Temp Range | Package | Status |
|---|---|---|---|---|---|---|---|---|---|
| HMA121 | onsemi | 3750Vrms | 50% | 600% | 80mA | 400mV | -40°C ~ 100°C | 4-SMD | Obsolete |
| FODM121 | onsemi | 3750Vrms | 50% | 600% | 80mA | 400mV | -40°C ~ 110°C | 4-SMD | Active |
| EL357ND(TA)-G | Everlight Electronics | 3750Vrms | 300% | 600% | 50mA | 200mV | -55°C ~ 110°C | 4-SOP | Active |
| HCPL-181-000E | Broadcom Limited | 3750Vrms | 50% | 600% | 50mA | 200mV | -55°C ~ 100°C | 4-SOIC | Active |
| HCPL-181-00AE | Broadcom Limited | 3750Vrms | 80% | 160% | 50mA | 200mV | -55°C ~ 100°C | 4-Mini-Flat | Active |
| HCPL-181-00BE | Broadcom Limited | 3750Vrms | 130% | 260% | 50mA | 200mV | -55°C ~ 100°C | 4-Mini-Flat | Active |
| HCPL-181-00CE | Broadcom Limited | 3750Vrms | 200% | 400% | 50mA | 200mV | -55°C ~ 100°C | 4-Mini-Flat | Active |
| HCPL-181-00DE | Broadcom Limited | 3750Vrms | 300% | 600% | 50mA | 200mV | -55°C ~ 100°C | 4-Mini-Flat | Active |
| HCPL-181-06BE | Broadcom Limited | 3750Vrms | 130% | 260% | 50mA | 200mV | -55°C ~ 100°C | 4-Mini-Flat | Active |
| HCPL-181-06DE | Broadcom Limited | 3750Vrms | 300% | 600% | 50mA | 200mV | -55°C ~ 100°C | 4-Mini-Flat | Active |
| LTV-356T | Lite-On Inc. | 3750Vrms | 50% | 600% | 50mA | 200mV | -55°C ~ 110°C | 4-SOP | Active |
Engineering Selection Recommendations
Direct Equivalent (Recommended Primary Substitute):
FODM121 (onsemi) is the direct equivalent to HMA121. It maintains identical electrical specifications including 3750Vrms isolation, 50% to 600% current transfer ratio, 80mA output current, and 400mV Vce saturation. FODM121 is active product status with extended operating temperature range (-40°C to 110°C) and ROHS3 compliance. This part provides the most direct replacement path with no design modifications required.
Alternative Substitutes (Package-Dependent Selection):
For applications where package footprint flexibility exists, the following active parts provide electrical equivalence with different mechanical configurations:
HCPL-181-00DE and HCPL-181-06DE (Broadcom Limited) match the HMA121 current transfer ratio range (300% to 600% @ 5mA) and maintain 3750Vrms isolation in 4-Mini-Flat packages. Both are ROHS3 compliant and active products. Output current is reduced to 50mA, requiring circuit verification for current-limited applications.
LTV-356T (Lite-On Inc.) provides 3750Vrms isolation with 50% to 600% current transfer ratio in 4-SOP package. Active product status with ROHS3 compliance and extended temperature range (-55°C to 110°C). Output current is 50mA.
EL357ND(TA)-G (Everlight Electronics) offers 3750Vrms isolation with 300% to 600% current transfer ratio in 4-SOP package. Active product with ROHS3 compliance and extended temperature range (-55°C to 110°C). Output current is 50mA.
Partial Compatibility Substitutes:
HCPL-181-00AE, HCPL-181-00BE, and HCPL-181-06BE (Broadcom Limited) provide 3750Vrms isolation but with reduced current transfer ratio ranges (80% to 160% and 130% to 260% respectively). These parts are suitable only for applications where the lower CTR range is acceptable. All are active, ROHS3 compliant, with 4-Mini-Flat packages.
HCPL-181-000E (Broadcom Limited) matches the HMA121 CTR range (50% to 600%) in 4-SOIC package with 3750Vrms isolation. Active product with ROHS3 compliance. Output current is 50mA.
Frequently Asked Questions (FAQ)
Q: Can FODM121 be used as a direct replacement for HMA121?
A: Yes. FODM121 is electrically and mechanically equivalent to HMA121 with identical isolation voltage, current transfer ratio range, output current, and saturation voltage. FODM121 is active product status, making it the recommended substitute for obsolete HMA121.
Q: What is the primary difference between HMA121 and the Broadcom HCPL-181 series?
A: The HCPL-181 series uses different package types (4-Mini-Flat or 4-SOIC) compared to HMA121's 4-SMD package. Electrical specifications vary by part number suffix. HCPL-181-00DE and HCPL-181-06DE match the full current transfer ratio range of HMA121 (300% to 600% @ 5mA), while other variants have narrower CTR ranges. All HCPL-181 variants reduce output current to 50mA.
Q: Are there output current limitations when substituting HMA121?
A: Yes. HMA121 provides 80mA output current. Most substitute parts (HCPL-181 series, EL357ND(TA)-G, LTV-356T) reduce this to 50mA. FODM121 maintains 80mA output current. Applications requiring the full 80mA output should prioritize FODM121 or verify that 50mA is sufficient for the circuit design.
Q: What package considerations apply when selecting substitutes?
A: HMA121 uses 4-SMD package. FODM121 maintains this package. Alternative packages include 4-Mini-Flat (HCPL-181 series), 4-SOIC (HCPL-181-000E), and 4-SOP (EL357ND(TA)-G, LTV-356T). Package changes require PCB layout modifications and footprint verification.
Q: Do all substitute parts meet RoHS compliance?
A: FODM121 is ROHS3 compliant. All Broadcom HCPL-181 variants, Everlight EL357ND(TA)-G, and Lite-On LTV-356T are ROHS3 compliant. HMA121 product status is obsolete with no RoHS designation provided.
Q: Which substitute offers the widest operating temperature range?
A: EL357ND(TA)-G and LTV-356T both support -55°C to 110°C operating range, exceeding HMA121's -40°C to 100°C range. FODM121 supports -40°C to 110°C. HCPL-181 series supports -55°C to 100°C.
Q: Can HCPL-181-00AE be used if current transfer ratio is not critical?
A: HCPL-181-00AE has a narrower CTR range (80% to 160% @ 5mA) compared to HMA121 (50% to 600%). This part is suitable only for applications where the lower CTR specification is acceptable and does not affect circuit performance. Circuit analysis is required to confirm compatibility.
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