TIP121 NPN Darlington Transistor Equivalent & Substitute Parts

Part Overview

The TIP121 is a bipolar NPN Darlington transistor manufactured by Central Semiconductor Corp, designed for high-current switching and amplification applications. It features an 80 V collector-emitter breakdown voltage rating and 5 A maximum collector current capability in a Through Hole TO-220-3 package. The TIP121 is classified as an obsolete product, necessitating identification of active equivalent alternatives for new designs and ongoing production requirements. Substitute parts must maintain electrical and mechanical compatibility while meeting current manufacturing and compliance standards.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN - Darlington	-
Current - Collector (Ic) (Max)	5	A
Voltage - Collector Emitter Breakdown (Max)	80	V
Vce Saturation (Max) @ Ib, Ic	4V @ 20mA, 5A	-
Current - Collector Cutoff (Max)	500	µA
DC Current Gain (hFE) (Min) @ Ic, Vce	1000 @ 3A, 3V	-
Operating Temperature Range	-65 to 150	°C (TJ)
Mounting Type	Through Hole	-
Package / Case	TO-220-3	-

Substitute Part Grouping Explanation

Substitution of the TIP121 is determined by strict equivalence across the following critical electrical and mechanical parameters:

Electrical Equivalence Criteria:

Transistor Type: NPN - Darlington configuration
Maximum Collector Current (Ic): 5 A
Collector-Emitter Breakdown Voltage: 80 V
Saturation Voltage (Vce): 4V @ 20mA, 5A
Collector Cutoff Current: 500 µA
DC Current Gain (hFE): 1000 @ 3A, 3V
Operating Temperature Range: -65°C to 150°C

Mechanical Equivalence Criteria:

Mounting Type: Through Hole
Package: TO-220-3

The TIP121G from onsemi meets all specified electrical parameters and maintains identical mechanical compatibility. This substitute is classified as an active product with current manufacturing status and RoHS3 compliance, addressing the obsolescence of the original TIP121.

Parameter Comparison

Parameter	TIP121 (Central Semiconductor)	TIP121G (onsemi)	Match Status
Transistor Type	NPN - Darlington	NPN - Darlington	Equivalent
Current - Collector (Ic) (Max)	5 A	5 A	Equivalent
Voltage - Collector Emitter Breakdown (Max)	80 V	80 V	Equivalent
Vce Saturation (Max) @ Ib, Ic	4V @ 20mA, 5A	4V @ 20mA, 5A	Equivalent
Current - Collector Cutoff (Max)	500 µA	500 µA	Equivalent
DC Current Gain (hFE) (Min) @ Ic, Vce	1000 @ 3A, 3V	1000 @ 3A, 3V	Equivalent
Operating Temperature Range	-65°C to 150°C	-65°C to 150°C	Equivalent
Mounting Type	Through Hole	Through Hole	Equivalent
Package / Case	TO-220-3	TO-220-3	Equivalent
Product Status	Obsolete	Active	Substitute is Active
RoHS Status	RoHS non-compliant	RoHS3 Compliant	Substitute is Compliant

Engineering Selection Recommendations

The TIP121G from onsemi is the direct substitute for the obsolete TIP121. Selection of TIP121G is based on the following engineering factors:

Product Status: The TIP121G maintains active manufacturing status, ensuring long-term availability and supply chain continuity. The original TIP121 is obsolete and subject to inventory depletion.

Regulatory Compliance: The TIP121G is RoHS3 compliant, meeting current environmental and regulatory requirements for electronic components. The original TIP121 is RoHS non-compliant, creating compliance barriers for new product certifications and market access.

Electrical Compatibility: All critical electrical parameters are identical between the TIP121 and TIP121G, including collector current, breakdown voltage, saturation characteristics, and gain specifications. Direct functional substitution is supported without circuit modification.

Mechanical Compatibility: Both devices utilize the TO-220-3 Through Hole package, enabling direct PCB footprint compatibility and thermal management equivalence.

REACH and Trade Compliance: Both the TIP121 and TIP121G maintain REACH Unaffected status and EAR99 export classification, with identical HTSUS coding (8541.29.0095).

Frequently Asked Questions (FAQ)

Q: Can TIP121G be used as a direct replacement for TIP121 without circuit modifications?

A: Yes. The TIP121G meets all electrical specifications of the TIP121, including collector current (5 A), breakdown voltage (80 V), saturation voltage (4V @ 20mA, 5A), and DC current gain (1000 @ 3A, 3V). The TO-220-3 package is mechanically identical. Direct substitution is supported.

Q: What is the primary reason for substituting TIP121 with TIP121G?

A: The TIP121 is classified as obsolete, creating supply and availability risks. The TIP121G is an active product from onsemi with current manufacturing status and RoHS3 compliance, addressing both obsolescence and regulatory requirements.

Q: Are there package differences between TIP121 and TIP121G?

A: Both devices use the TO-220-3 Through Hole package. The TIP121G is supplied in Tube packaging format, while the original TIP121 packaging format is not specified. The component footprint and thermal characteristics remain identical.

Q: Does TIP121G meet RoHS compliance requirements?

A: Yes. The TIP121G is RoHS3 compliant. The original TIP121 is RoHS non-compliant. For applications requiring RoHS certification, TIP121G is the appropriate selection.

Q: Are there any electrical parameter differences that would affect circuit performance?

A: No. All specified electrical parameters are identical: Ic (5 A), Vce breakdown (80 V), saturation voltage (4V @ 20mA, 5A), cutoff current (500 µA), and DC gain (1000 @ 3A, 3V). Operating temperature range is also identical (-65°C to 150°C).

Q: What is the inventory status of TIP121G?

A: TIP121G has 2400 pieces of new original stock currently available. The original TIP121 has 44300 pieces in stock but is obsolete.

Q: Are there any trade or export restrictions on TIP121G?

A: No. TIP121G carries EAR99 export classification and REACH Unaffected status, identical to the original TIP121. HTSUS code is 8541.29.0095 for both devices.

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