IL251-X009T Equivalent & Substitute Parts

Part Overview

The IL251-X009T is a Vishay Semiconductor optoisolator transistor with base output, rated for 5300Vrms isolation voltage in a 6-SMD surface mount package. This component is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The part provides single-channel optoisolation with AC/DC input capability and transistor output with base connection, suitable for applications requiring galvanic isolation in industrial and power management circuits.

Key Parameters

Parameter	IL251-X009T
Manufacturer	Vishay Semiconductor Opto Division
Product Status	Obsolete
Number of Channels	1
Voltage - Isolation	5300Vrms
Current Transfer Ratio (Min)	20% @ 10mA
Input Type	AC, DC
Output Type	Transistor with Base
Voltage - Output (Max)	30V
Voltage - Forward (Vf) (Typ)	1.2V
Current - DC Forward (If) (Max)	60 mA
Vce Saturation (Max)	400mV
Operating Temperature	-55°C ~ 100°C
Mounting Type	Surface Mount
Package / Case	6-SMD, Gull Wing
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the IL251-X009T is determined by the following critical parameters:

Number of Channels: Must be 1 (single channel)
Output Type: Must be Transistor with Base
Input Type: Must support AC, DC
Mounting Type: Must be Surface Mount
Package / Case: Must be 6-SMD, Gull Wing
Voltage - Isolation: Minimum 4170Vrms (acceptable for applications designed for 5300Vrms)
Current Transfer Ratio (Min): Minimum 20% @ 10mA
Voltage - Output (Max): Minimum 30V
Vce Saturation (Max): Maximum 400mV
RoHS Status: ROHS3 Compliant

The substitute parts are grouped into two categories based on isolation voltage specification and manufacturer:

Group 1 - onsemi H11AA Series (4170Vrms): H11AA1SM, H11AA1SR2M, H11AA1SR2VM, H11AA4SM. These parts meet all critical parameters with active product status and standardized packaging options.

Group 2 - Isocom H11A Series (7.5Vpk): H11AA1SMT&R, H11AA2SMT&R, H11AA3SMT&R, H11AA4SMT&R. These parts provide higher isolation voltage specification and active product status with tape & reel packaging.

Parameter Comparison

Parameter	IL251-X009T	H11AA1SM	H11AA1SR2M	H11AA1SR2VM	H11AA4SM	H11AA1SMT&R	H11AA2SMT&R	H11AA3SMT&R	H11AA4SMT&R
Manufacturer	Vishay	onsemi	onsemi	onsemi	onsemi	Isocom	Isocom	Isocom	Isocom
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active
Number of Channels	1	1	1	1	1	1	1	1	1
Voltage - Isolation	5300Vrms	4170Vrms	4170Vrms	4170Vrms	4170Vrms	7.5Vpk	7.5Vpk	7.5Vpk	7.5Vpk
Current Transfer Ratio (Min)	20% @ 10mA	20% @ 10mA	20% @ 10mA	20% @ 10mA	100% @ 10mA	20% @ 10mA	10% @ 10mA	50% @ 10mA	100% @ 10mA
Input Type	AC, DC	AC, DC	AC, DC	AC, DC	AC, DC	AC, DC	AC, DC	AC, DC	AC, DC
Output Type	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base	Transistor with Base
Voltage - Output (Max)	30V	30V	30V	30V	30V	35V	35V	35V	35V
Current - Output / Channel	Not specified	50mA	50mA	50mA	50mA	50mA	50mA	50mA	50mA
Voltage - Forward (Vf) (Typ)	1.2V	1.17V	1.17V	1.17V	1.17V	1.2V	1.2V	1.2V	1.2V
Current - DC Forward (If) (Max)	60 mA	60 mA	60 mA	60 mA	60 mA	50 mA	50 mA	50 mA	50 mA
Vce Saturation (Max)	400mV	400mV	400mV	400mV	400mV	400mV	400mV	400mV	400mV
Operating Temperature	-55°C ~ 100°C	-40°C ~ 100°C	-40°C ~ 100°C	-40°C ~ 100°C	-40°C ~ 100°C	-30°C ~ 100°C	-30°C ~ 100°C	-30°C ~ 100°C	-30°C ~ 100°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing	6-SMD, Gull Wing
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

All listed substitute parts are ROHS3 compliant with MSL rating of 1 (Unlimited), matching the environmental and regulatory requirements of the IL251-X009T.

Primary Substitutes (onsemi H11AA Series): H11AA1SM, H11AA1SR2M, H11AA1SR2VM, and H11AA4SM are active products with established supply chains. These parts maintain compatibility with the original 6-SMD gull wing package and support AC/DC input operation. The onsemi H11AA1 variants (H11AA1SM, H11AA1SR2M, H11AA1SR2VM) provide 4170Vrms isolation with 20% minimum current transfer ratio, directly matching the original part's transfer ratio specification. H11AA4SM offers enhanced performance with 100% minimum current transfer ratio while maintaining 4170Vrms isolation and active product status.

Secondary Substitutes (Isocom H11A Series): H11AA1SMT&R, H11AA2SMT&R, H11AA3SMT&R, and H11AA4SMT&R are active products supplied in tape & reel packaging. These parts provide 7.5Vpk isolation specification with current transfer ratios ranging from 10% to 100%, accommodating various application requirements. Operating temperature range is -30°C to 100°C, which is narrower than the original part's -55°C to 100°C specification.

Selection between onsemi and Isocom variants depends on packaging requirements (cut tape/digi-reel versus tape & reel), current transfer ratio performance needs, and operating temperature constraints.

Frequently Asked Questions (FAQ)

Q: Can H11AA1SM directly replace IL251-X009T?

A: H11AA1SM is functionally compatible for applications where 4170Vrms isolation is acceptable. Both parts share identical package geometry (6-SMD gull wing), single-channel transistor output with base, AC/DC input capability, 20% minimum current transfer ratio, 30V maximum output voltage, and 400mV maximum Vce saturation. The primary difference is isolation voltage rating (4170Vrms versus 5300Vrms) and operating temperature range (-40°C to 100°C versus -55°C to 100°C).

Q: What is the difference between onsemi and Isocom substitute options?

A: onsemi H11AA series parts (H11AA1SM, H11AA1SR2M, H11AA1SR2VM, H11AA4SM) specify 4170Vrms isolation voltage and operate from -40°C to 100°C. Isocom H11A series parts (H11AA1SMT&R, H11AA2SMT&R, H11AA3SMT&R, H11AA4SMT&R) specify 7.5Vpk isolation voltage and operate from -30°C to 100°C. Both manufacturers provide ROHS3 compliant parts in 6-SMD gull wing packages with identical output voltage and saturation specifications.

Q: Does packaging format affect electrical performance?

A: No. Packaging format (tube, cut tape, tape & reel) does not affect electrical performance. Selection is based on procurement and assembly requirements. H11AA1SM is supplied in tube format, H11AA1SR2M in cut tape with digi-reel, H11AA1SR2VM in tape & reel, and Isocom variants in tape & reel format.

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

A: Current transfer ratio determines the output current relative to input current. IL251-X009T and H11AA1 variants specify 20% minimum, while H11AA4 variants specify 100% minimum. Higher current transfer ratio provides greater output current for the same input current, improving switching performance in applications with limited input drive capability.

Q: Are there temperature range limitations for substitution?

A: IL251-X009T operates from -55°C to 100°C. onsemi H11AA series operates from -40°C to 100°C, and Isocom H11A series operates from -30°C to 100°C. Applications requiring operation below -40°C must use the original IL251-X009T or equivalent parts with extended low-temperature ratings.

Q: Is the 6-SMD gull wing package compatible with existing PCB layouts?

A: Yes. All substitute parts use identical 6-SMD gull wing package geometry, ensuring direct PCB footprint compatibility without layout modifications.

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