ST901TFP Equivalent & Substitute Parts

Part Overview

The ST901TFP is an NPN Darlington bipolar junction transistor manufactured by STMicroelectronics, rated for 400 V collector-emitter breakdown voltage and 4 A maximum collector current in a TO-220FP through-hole package. This device is classified as obsolete product status. Locating equivalent and substitute parts is necessary due to discontinued manufacturing and limited inventory availability for new designs and production requirements.

Substiute Parts

ST901TFP

STMicroelectronicsIn Stock: 1157ST901TFP Datasheet

Current PartRFQ

ST901T

STMicroelectronicsIn Stock: 5460ST901T Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the ST901TFP is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

• Transistor type must be NPN - Darlington configuration
• Collector current rating must equal or exceed 4 A
• Collector-emitter breakdown voltage must equal or exceed 400 V
• Saturation voltage characteristics must be compatible with circuit requirements
• DC current gain (hFE) must meet or exceed minimum specified values

Mechanical Compatibility Criteria:

• Mounting type must be through-hole
• Package must be TO-220-3 or equivalent footprint
• Lead configuration must match circuit board design

Compliance Criteria:

• RoHS3 compliance required
• REACH unaffected status required
• ECCN classification EAR99

The ST901T qualifies as a direct substitute based on these parameters, with the following considerations: it maintains NPN Darlington configuration, 4 A collector current rating, and through-hole TO-220 mounting. However, the collector-emitter breakdown voltage is rated at 350 V, which is lower than the ST901TFP specification of 400 V. This substitution is valid only for applications where the maximum operating voltage does not exceed 350 V.

Parameter Comparison

Engineering Selection Recommendations

ST901T as Substitute for ST901TFP:

The ST901T is an active product with current manufacturing status, providing supply continuity for the obsolete ST901TFP. Both devices share identical NPN Darlington configuration, 4 A collector current rating, and TO-220-3 through-hole package footprint.

The ST901T exhibits superior electrical characteristics in several areas: maximum power dissipation is increased to 100 W compared to 80 W, DC current gain is higher at 1800 minimum versus 1500 minimum, and moisture sensitivity is improved to MSL 1 (unlimited) versus MSL 3 (168 hours).

The primary electrical difference is the collector-emitter breakdown voltage specification: ST901T is rated at 350 V maximum compared to ST901TFP at 400 V maximum. Selection of ST901T is appropriate for applications operating at or below 350 V. Applications requiring operation above 350 V must retain the ST901TFP or identify alternative devices with 400 V or higher ratings.

Both devices maintain ROHS3 compliance and REACH unaffected status, satisfying regulatory requirements for equivalent substitution.

Frequently Asked Questions (FAQ)

Q: Can ST901T directly replace ST901TFP in all applications?

A: ST901T is a direct mechanical and functional substitute for applications operating at 350 V or below. Applications requiring 400 V operation must use ST901TFP or identify alternative devices rated for 400 V collector-emitter breakdown voltage.

Q: What is the difference in package between ST901TFP and ST901T?

A: Both devices use TO-220-3 through-hole packages with identical footprints and lead configurations. ST901TFP is supplied in Tape & Reel packaging, while ST901T is supplied in Tube packaging. The physical component dimensions and circuit board mounting requirements are identical.

Q: Are there compliance differences between ST901TFP and ST901T?

A: Both devices are ROHS3 compliant and REACH unaffected. ST901T has improved moisture sensitivity rating (MSL 1 unlimited versus MSL 3 168 hours), which may provide advantages for storage and handling in humid environments.

Q: What are the key electrical parameters that determine substitution eligibility?

A: Substitution eligibility is determined by: transistor type (NPN Darlington), collector current rating (4 A minimum), collector-emitter breakdown voltage (350 V minimum for ST901T), saturation voltage characteristics, and DC current gain specifications. The ST901T meets all these criteria with the voltage limitation noted above.

Q: Why is ST901TFP classified as obsolete?

A: ST901TFP is classified as obsolete due to discontinued manufacturing by STMicroelectronics. The ST901T serves as the active replacement product, maintaining functional equivalence while offering improved electrical performance and compliance characteristics.

Q: Can ST901T handle higher power dissipation than ST901TFP?

A: Yes. ST901T is rated for 100 W maximum power dissipation compared to 80 W for ST901TFP. This increased power rating provides additional thermal margin in applications approaching maximum current and voltage specifications.