ILD621 Equivalent & Substitute Parts

Part Overview

The ILD621 is a 2-channel optoisolator with transistor output manufactured by Vishay Semiconductor Opto Division. It provides 5300Vrms isolation voltage and is designed for DC input applications requiring galvanic isolation in 8-DIP through-hole packaging. The ILD621 is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain compatibility across isolation voltage, channel configuration, output type, and package form factor while meeting current availability and active product status requirements.

Key Parameters

Parameter	ILD621 Specification
Manufacturer	Vishay Semiconductor Opto Division
Category	Optoisolators
Product Status	Obsolete
Number of Channels	2
Voltage - Isolation	5300Vrms
Output Type	Transistor
Input Type	DC
Mounting Type	Through Hole
Package / Case	8-DIP (0.300", 7.62mm)
Current Transfer Ratio (Min)	50% @ 5mA
Current Transfer Ratio (Max)	600% @ 5mA
Voltage - Output (Max)	70V
Current - Output / Channel	50mA
Operating Temperature	-55°C ~ 100°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Primary Compatibility Criteria:

Number of Channels: Must be 2
Output Type: Must be Transistor
Input Type: Must be DC
Mounting Type: Must be Through Hole
Package / Case: Must be 8-DIP configuration
Isolation Voltage: Minimum 5000Vrms (ILD621 specifies 5300Vrms)

Secondary Compatibility Criteria:

Voltage - Output (Max): Minimum 70V
Current - Output / Channel: Minimum 50mA
Current Transfer Ratio range overlap with ILD621 (50% to 600% @ 5mA)
Operating Temperature range: Must support -55°C to 100°C or equivalent industrial range
RoHS3 Compliance and REACH Unaffected status

Substitute parts are grouped into two categories based on package physical dimensions and isolation voltage specifications:

Group A - Direct Package Match (0.300", 7.62mm): MCT9001 and TLP321-2X maintain the original compact 8-DIP footprint and support the full -55°C to 100°C operating temperature range.

Group B - Alternative Package (0.400", 10.16mm): ACPL-827 series variants (ACPL-827-W0BE, ACPL-827-W0CE, ACPL-827-W60E, ACPL-827-W6BE, ACPL-827-W6CE) provide 5000Vrms isolation with wider pitch 8-DIP packaging and operate within -30°C to 100°C range.

Parameter Comparison

Parameter	ILD621	ACPL-827-W0BE	ACPL-827-W0CE	ACPL-827-W60E	ACPL-827-W6BE	ACPL-827-W6CE	MCT9001	TLP321-2X
Manufacturer	Vishay	Broadcom	Broadcom	Broadcom	Broadcom	Broadcom	onsemi	Isocom
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active
Number of Channels	2	2	2	2	2	2	2	2
Voltage - Isolation	5300Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5000Vrms	5300Vrms
Current Transfer Ratio (Min)	50% @ 5mA	130% @ 5mA	200% @ 5mA	50% @ 5mA	130% @ 5mA	200% @ 5mA	50% @ 5mA	50% @ 5mA
Current Transfer Ratio (Max)	600% @ 5mA	260% @ 5mA	400% @ 5mA	600% @ 5mA	260% @ 5mA	400% @ 5mA	600% @ 5mA	600% @ 5mA
Voltage - Output (Max)	70V	70V	70V	70V	70V	70V	55V	80V
Current - Output / Channel	50mA	50mA	50mA	50mA	50mA	50mA	30mA	Not specified
Vce Saturation (Max)	400mV	200mV	200mV	200mV	200mV	200mV	400mV	400mV
Operating Temperature	-55°C ~ 100°C	-30°C ~ 100°C	-30°C ~ 100°C	-30°C ~ 100°C	-30°C ~ 100°C	-30°C ~ 100°C	-55°C ~ 100°C	-55°C ~ 100°C
Package / Case	8-DIP (0.300", 7.62mm)	8-DIP (0.400", 10.16mm)	8-DIP (0.400", 10.16mm)	8-DIP (0.400", 10.16mm)	8-DIP (0.400", 10.16mm)	8-DIP (0.400", 10.16mm)	8-DIP (0.300", 7.62mm)	8-DIP (0.300", 7.62mm)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For PCB Layout Compatibility (No Redesign Required):

MCT9001 and TLP321-2X are preferred substitutes when PCB footprint constraints require the original 0.300" (7.62mm) 8-DIP pitch. Both parts are active products with ROHS3 compliance. MCT9001 provides identical current transfer ratio range (50% to 600% @ 5mA) and operating temperature range (-55°C to 100°C) as the ILD621. TLP321-2X matches isolation voltage (5300Vrms) and operating temperature range, with slightly higher maximum output voltage (80V vs 70V).

For New Designs with Layout Flexibility:

ACPL-827 series variants (W0BE, W0CE, W60E, W6BE, W6CE) are active Broadcom products with 5000Vrms isolation and 0.400" (10.16mm) 8-DIP pitch. Selection within this series depends on current transfer ratio requirements:

W0BE and W6BE: 130% to 260% @ 5mA
W0CE and W6CE: 200% to 400% @ 5mA
W60E: 50% to 600% @ 5mA (full range match)

All ACPL-827 variants operate within -30°C to 100°C, which is acceptable for most industrial applications but does not extend to -55°C.

Critical Considerations:

MCT9001 has reduced maximum output current (30mA vs 50mA per channel) and maximum output voltage (55V vs 70V), requiring circuit verification for applications at design limits. ACPL-827 series variants have lower maximum Vce saturation (200mV vs 400mV), which may improve efficiency in switching applications. Operating temperature range narrows to -30°C minimum for ACPL-827 parts; applications requiring -55°C operation must use MCT9001 or TLP321-2X.

Frequently Asked Questions (FAQ)

Q: Can ACPL-827 series parts be used as direct pin-for-pin replacements for ILD621?

A: ACPL-827 parts are functionally compatible but require PCB layout modification due to different 8-DIP pitch (0.400" vs 0.300"). Pin assignments are identical, but the wider spacing necessitates new footprint design. MCT9001 and TLP321-2X maintain the original 0.300" pitch for direct substitution without layout changes.

Q: What is the isolation voltage difference between ILD621 (5300Vrms) and ACPL-827 (5000Vrms)?

A: The 300Vrms difference represents a 5.7% reduction in isolation capability. For applications where 5300Vrms isolation is a design requirement, MCT9001 or TLP321-2X must be selected. For applications where 5000Vrms meets isolation specifications, ACPL-827 variants are acceptable.

Q: Which substitute part has the best current transfer ratio match to ILD621?

A: ACPL-827-W60E and MCT9001 both provide 50% to 600% @ 5mA current transfer ratio, identical to ILD621. TLP321-2X also matches this range. ACPL-827-W0BE, W0CE, W6BE, and W6CE have narrower ranges (130-260% or 200-400%) and are suitable only for applications tolerant of higher minimum CTR values.

Q: Are there temperature range limitations when substituting ILD621?

A: ILD621 and MCT9001 both operate -55°C to 100°C. TLP321-2X also supports this full range. ACPL-827 series variants operate -30°C to 100°C, limiting use in applications requiring extended low-temperature operation below -30°C.

Q: What is the significance of Vce saturation differences (400mV vs 200mV)?

A: Lower Vce saturation in ACPL-827 variants (200mV) reduces output transistor voltage drop compared to ILD621, MCT9001, and TLP321-2X (400mV). This improves efficiency in high-frequency switching applications and reduces power dissipation, but does not affect functional compatibility.

Q: Can MCT9001 be used in applications requiring 50mA output current per channel?

A: MCT9001 is rated for 30mA maximum output current per channel, compared to ILD621's 50mA. Applications designed for 50mA operation require either TLP321-2X, ACPL-827 series, or circuit redesign to operate within MCT9001's 30mA limit.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. ILD621, MCT9001, TLP321-2X, and all ACPL-827 variants are ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements.

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