4N24 Optoisolator Transistor with Base Output — Equivalent & Substitute Parts

Part Overview

The 4N24 is a single-channel optoisolator with transistor output and base connection, rated for 1000VDC isolation. Manufactured by TT Electronics / Optek Technology, this through-hole component operates across the industrial temperature range of -65°C to 125°C and is currently in active production status. The device is housed in a TO-78-6 metal can package and complies with RoHS3 and REACH regulations.

Substitute parts become necessary when the primary part reaches end-of-life status, inventory constraints occur, or design revisions require alternative sourcing. The 4N24ATXV represents a parametric equivalent with identical electrical and mechanical specifications, though with different compliance and availability characteristics.

Key Parameters

Parameter	Value
Number of Channels	1
Voltage - Isolation	1000VDC
Current Transfer Ratio (Min)	100% @ 10mA
Rise / Fall Time (Typ)	20µs, 20µs
Input Type	DC
Output Type	Transistor with Base
Voltage - Output (Max)	35V
Current - Output / Channel	50mA
Voltage - Forward (Vf) (Typ)	1.3V (Max)
Current - DC Forward (If) (Max)	40mA
Vce Saturation (Max)	300mV
Operating Temperature	-65°C ~ 125°C
Mounting Type	Through Hole
Package / Case	TO-78-6 Metal Can
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the 4N24 optoisolator is determined by strict equivalence across the following critical parameters:

Isolation Voltage: 1000VDC minimum
Number of Channels: Single channel only
Output Configuration: Transistor with base connection
Current Transfer Ratio: 100% @ 10mA minimum
Output Voltage Rating: 35V maximum
Output Current: 50mA per channel
Switching Characteristics: Rise/fall times of 20µs
Package Type: TO-78-6 metal can through-hole
Temperature Range: -65°C to 125°C

The 4N24ATXV meets all electrical and mechanical substitution criteria. Both parts share identical functional specifications, pin configurations, and performance characteristics. Differences exist only in product status and regulatory compliance classifications.

Parameter Comparison

Parameter	4N24 (Main Part)	4N24ATXV (Substitute)
Manufacturer	TT Electronics / Optek Technology	TT Electronics / Optek Technology
Number of Channels	1	1
Voltage - Isolation	1000VDC	1000VDC
Current Transfer Ratio (Min)	100% @ 10mA	100% @ 10mA
Rise / Fall Time (Typ)	20µs, 20µs	20µs, 20µs
Input Type	DC	DC
Output Type	Transistor with Base	Transistor with Base
Voltage - Output (Max)	35V	35V
Current - Output / Channel	50mA	50mA
Voltage - Forward (Vf) (Typ)	1.3V (Max)	1.3V (Max)
Current - DC Forward (If) (Max)	40mA	40mA
Vce Saturation (Max)	300mV	300mV
Operating Temperature	-65°C ~ 125°C	-65°C ~ 125°C
Mounting Type	Through Hole	Through Hole
Package / Case	TO-78-6 Metal Can	TO-78-6 Metal Can
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)
Product Status	Active	Obsolete
RoHS Status	RoHS3 Compliant	RoHS non-compliant

Engineering Selection Recommendations

Primary Selection: The 4N24 is the preferred choice for new designs and production applications. Active product status ensures long-term availability and supply chain stability. RoHS3 compliance satisfies regulatory requirements for consumer and industrial markets.

Substitute Selection: The 4N24ATXV is electrically and mechanically equivalent and suitable for legacy system maintenance, field replacements, or applications where RoHS compliance is not mandated. The obsolete status indicates limited future availability; this part should be selected only when the primary part cannot be sourced.

Compliance Considerations: Applications subject to RoHS3 or REACH regulations must use the 4N24. The 4N24ATXV's non-compliant status restricts its use to non-regulated markets or legacy equipment repair.

Frequently Asked Questions (FAQ)

Q: Can the 4N24ATXV be used as a direct replacement for the 4N24?

A: Yes, from an electrical and mechanical standpoint. Both parts are parametrically identical with matching isolation voltage, output configuration, current ratings, and package type. However, regulatory compliance differs; the 4N24 is RoHS3 compliant while the 4N24ATXV is not.

Q: What determines whether a part qualifies as a substitute for the 4N24?

A: Substitution requires matching across all critical parameters: 1000VDC isolation voltage, single-channel transistor output with base connection, 100% CTR @ 10mA minimum, 35V output voltage rating, 50mA output current, 20µs rise/fall times, TO-78-6 package, and -65°C to 125°C operating range.

Q: Why is the 4N24ATXV marked as obsolete?

A: Obsolete status indicates the manufacturer has discontinued active production. The part may still be available through inventory channels but future availability is not guaranteed.

Q: Are there any pin configuration differences between the 4N24 and 4N24ATXV?

A: No. Both parts use the TO-78-6 metal can package with identical pinout and electrical connections.

Q: Which part should be selected for new product designs?

A: The 4N24 should be selected for new designs. Active production status and RoHS3 compliance ensure regulatory alignment and supply chain continuity.

Q: Can the 4N24ATXV be used in applications requiring RoHS3 certification?

A: No. The 4N24ATXV is RoHS non-compliant and cannot be used in applications or markets requiring RoHS3 certification.

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