H11A4TM Optoisolator Equivalent & Substitute Parts

Part Overview

The H11A4TM is a transistor output optoisolator manufactured by onsemi, featuring 7500Vpk isolation voltage in a 6-DIP through-hole package. This component provides galvanic isolation for DC input signals with transistor and base outputs suitable for switching and signal conditioning applications. The H11A4TM is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	H11A4TM Value
Manufacturer	onsemi
Category	Optoisolators
Product Status	Obsolete
Number of Channels	1
Voltage - Isolation	7500Vpk
Current Transfer Ratio (Min)	10% @ 10mA
Turn On / Turn Off Time (Typ)	2µs, 2µs
Input Type	DC
Output Type	Transistor with Base
Voltage - Output (Max)	30V
Voltage - Forward (Vf) (Typ)	1.18V
Current - DC Forward (If) (Max)	60 mA
Vce Saturation (Max)	400mV
Operating Temperature	-40°C ~ 100°C
Mounting Type	Through Hole
Package / Case	6-DIP (0.400", 10.16mm)
Moisture Sensitivity Level (MSL)	1 (Unlimited)
REACH Status	REACH Unaffected

Substitute Part Grouping Explanation

Substitution for the H11A4TM is determined by the following critical parameters:

Primary Substitution Criteria:

Number of Channels: 1 (single channel required)
Output Type: Transistor with Base (functional output configuration)
Input Type: DC (signal type compatibility)
Mounting Type: Through Hole (mechanical compatibility with existing PCB layouts)
Package / Case: 6-DIP form factor (pin count and spacing)

Secondary Compatibility Parameters:

Voltage - Isolation: Minimum 7500Vpk (isolation rating must meet or exceed original specification)
Current Transfer Ratio (Min): Minimum 10% @ 10mA (optical coupling efficiency)
Voltage - Output (Max): Minimum 30V (output voltage capability)
Operating Temperature: Must encompass -40°C ~ 100°C range or be compatible with application requirements

Substitute Parts Identified:

Group 1 - Direct Through-Hole DIP Equivalents (Highest Compatibility):

H11A4M (onsemi) - Identical electrical specifications, same 6-DIP package
H11A3M (Fairchild Semiconductor) - Through-hole 6-DIP, compatible isolation and output characteristics
H11A5M (Fairchild Semiconductor) - Through-hole 6-DIP, compatible isolation and output characteristics

Group 2 - Alternative Mounting Technology:

H11A2M (onsemi) - Surface mount 6-SMD variant, identical electrical performance but different mounting approach

Group 3 - Active Status Alternative:

H11A4G (Isocom Components 2004 LTD) - Through-hole 6-DIP, active product status, compatible core specifications

Parameter Comparison

Parameter	H11A4TM	H11A4M	H11A3M	H11A5M	H11A2M	H11A4G
Manufacturer	onsemi	onsemi	Fairchild Semiconductor	Fairchild Semiconductor	onsemi	Isocom Components 2004 LTD
Product Status	Obsolete	Obsolete	Obsolete	Obsolete	Obsolete	Active
Number of Channels	1	1	1	1	1	1
Voltage - Isolation	7500Vpk	7500Vpk	5000Vrms	5000Vrms	7500Vpk	7.5Vpk
Current Transfer Ratio (Min)	10% @ 10mA	10% @ 10mA	20% @ 10mA	30% @ 10mA	20% @ 10mA	10% @ 10mA
Turn On / Turn Off Time (Typ)	2µs, 2µs	2µs, 2µs	3µs, 3µs	3µs, 3µs	2µs, 2µs	—
Input Type	DC	DC	DC	DC	DC	DC
Output Type	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base
Voltage - Output (Max)	30V	30V	80V	80V	30V	30V
Voltage - Forward (Vf) (Typ)	1.18V	1.18V	1.2V	1.2V	1.18V	1.2V
Current - DC Forward (If) (Max)	60 mA	60 mA	60 mA	60 mA	60 mA	60 mA
Vce Saturation (Max)	400mV	400mV	400mV	400mV	400mV	400mV
Operating Temperature	-40°C ~ 100°C	-40°C ~ 100°C	-55°C ~ 110°C	-55°C ~ 110°C	-40°C ~ 100°C	-55°C ~ 100°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Surface Mount	Through Hole
Package / Case	6-DIP (0.400", 10.16mm)	6-DIP (0.300", 7.62mm)	6-DIP (0.400", 10.16mm)	6-DIP (0.400", 10.16mm)	6-SMD, Gull Wing	6-DIP (0.400", 10.16mm)
REACH Status	REACH Unaffected	REACH Unaffected	—	—	REACH Unaffected	REACH Unaffected
RoHS Status	—	—	ROHS3 Compliant	ROHS3 Compliant	—	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Through-Hole 6-DIP, Identical Specifications):

H11A4M (onsemi) provides the closest electrical match with identical isolation voltage (7500Vpk), current transfer ratio (10% @ 10mA), and switching speed (2µs). Both are obsolete products with REACH Unaffected status. Note the package dimension difference: H11A4M uses 6-DIP (0.300", 7.62mm) versus H11A4TM's 6-DIP (0.400", 10.16mm). Verify PCB footprint compatibility before selection.

For Enhanced Performance (Through-Hole 6-DIP, Higher CTR):

H11A3M and H11A5M (Fairchild Semiconductor) offer higher current transfer ratios (20% and 30% respectively) and extended output voltage capability (80V maximum). Both feature wider operating temperature range (-55°C ~ 110°C). Isolation voltage is specified as 5000Vrms rather than 7500Vpk; confirm this meets application isolation requirements. Both are ROHS3 Compliant and obsolete.

For Active Product Status (Through-Hole 6-DIP):

H11A4G (Isocom Components 2004 LTD) maintains active product status, ensuring ongoing availability and support. Electrical specifications match the H11A4TM core requirements (10% CTR, 30V output, 400mV saturation). Isolation voltage specification differs (7.5Vpk versus 7500Vpk); this represents a significant reduction and requires application-level verification. ROHS3 Compliant.

For Surface Mount Applications:

H11A2M (onsemi) provides identical electrical performance to H11A4TM in surface mount 6-SMD configuration. Select only if PCB design permits surface mount technology and assembly processes support SMD placement.

Frequently Asked Questions (FAQ)

Q: Can H11A4M be used as a direct replacement for H11A4TM?

A: H11A4M matches all electrical specifications (7500Vpk isolation, 10% CTR, 2µs switching) and product status (obsolete, REACH Unaffected). However, the package dimension differs: H11A4M is 6-DIP (0.300", 7.62mm) while H11A4TM is 6-DIP (0.400", 10.16mm). Verify PCB footprint compatibility before substitution.

Q: What is the difference between 7500Vpk and 5000Vrms isolation ratings?

A: These represent different measurement standards for isolation voltage. Peak voltage (Vpk) and RMS voltage (Vrms) are not directly equivalent. H11A3M and H11A5M specify 5000Vrms isolation, which differs from H11A4TM's 7500Vpk specification. Confirm application isolation requirements are met by the substitute part's rating.

Q: Why does H11A4G show 7.5Vpk isolation instead of 7500Vpk?

A: H11A4G specifies 7.5Vpk isolation voltage, which is substantially lower than H11A4TM's 7500Vpk. This represents a 1000-fold reduction in isolation capability. This part is suitable only for applications with significantly reduced isolation requirements.

Q: Can H11A2M replace H11A4TM in existing through-hole PCB designs?

A: H11A2M is a surface mount 6-SMD component, not compatible with through-hole PCB layouts. Select H11A2M only for new designs using surface mount assembly processes.

Q: Which substitute offers the best long-term availability?

A: H11A4G (Isocom Components 2004 LTD) is the only substitute with active product status, ensuring ongoing manufacturing and supply. All other substitutes are classified as obsolete. However, verify that H11A4G's 7.5Vpk isolation voltage meets application requirements before selection.

Q: Are all substitutes ROHS3 compliant?

A: H11A3M, H11A5M, and H11A4G are ROHS3 Compliant. H11A4M and H11A2M (onsemi) do not specify RoHS status in available documentation. Confirm RoHS compliance requirements with your procurement or quality department.

Q: What is the significance of current transfer ratio differences among substitutes?

A: Current transfer ratio (CTR) determines optical coupling efficiency. H11A4TM and H11A4M specify 10% minimum CTR, while H11A3M (20%), H11A5M (30%), and H11A2M (20%) offer higher efficiency. Higher CTR provides better signal transmission but does not affect isolation voltage or output voltage ratings. Select based on circuit design requirements for input current and output signal fidelity.

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