2SC1740STPQ Equivalent & Substitute Parts Reference

Part Overview

The Rohm Semiconductor 2SC1740STPQ is an NPN bipolar junction transistor (BJT) specified for 50 V collector-emitter breakdown voltage, 150 mA collector current, 300 mW maximum power, 180 MHz transition frequency, and through hole SC-72 (SPT) package. This part is classified as obsolete, prompting the requirement to identify suitable substitute models for ongoing production or maintenance. Accurate substitution requires strict parameter matching within the Transistors, Bipolar (BJT) category.

Key Parameters

Parameter	2SC1740STPQ Value
Transistor Type	NPN
Voltage - Collector Emitter Breakdown (Max)	50 V
Current - Collector (Ic) (Max)	150 mA
Vce Saturation (Max) @ Ib, Ic	400 mV @ 5 mA, 50 mA
Current - Collector Cutoff (Max) (ICBO)	100 nA
DC Current Gain (hFE) (Min) @ Ic, Vce	120 @ 1 mA, 6 V
Power - Max	300 mW
Frequency - Transition	180 MHz
Operating Temperature (TJ)	150°C
Mounting Type	Through Hole
Package / Case	SC-72 Formed Leads
Supplier Device Package	SPT
RoHS Status	ROHS3 Compliant
REACH Status	REACH Unaffected

Substitute Part Grouping Explanation

Strict substitution of the 2SC1740STPQ is determined by direct comparison of key electrical and mechanical parameters: transistor type, collector-emitter breakdown voltage, maximum collector current, collector cutoff current, DC current gain at specified conditions, maximum power dissipation, frequency transition, Vce saturation voltage at defined currents, maximum junction temperature, mounting type, and package equivalency. Compliance attributes such as RoHS and REACH are also matched for regulatory compatibility.

Parameter Comparison

Parameter	2SC1740STPQ (Rohm Semiconductor)	KSC945YTA (onsemi)
Transistor Type	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	50 V	50 V
Current - Collector (Ic) (Max)	150 mA	150 mA
Vce Saturation (Max) @ Ib, Ic	400 mV @ 5 mA, 50 mA	300 mV @ 10 mA, 100 mA
Current - Collector Cutoff (Max) (ICBO)	100 nA	100 nA
DC Current Gain (hFE) (Min) @ Ic, Vce	120 @ 1 mA, 6 V	120 @ 1 mA, 6 V
Power - Max	300 mW	250 mW
Frequency - Transition	180 MHz	300 MHz
Operating Temperature (TJ)	150°C	150°C
Mounting Type	Through Hole	Through Hole
Package / Case	SC-72 Formed Leads	TO-226-3, TO-92-3 (TO-226AA) Formed Leads
Supplier Device Package	SPT	TO-92-3
RoHS Status	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

Selection of substitute parts is primarily influenced by the product status designation. The 2SC1740STPQ is obsolete, while KSC945YTA is active. Both parts are compliant with ROHS3 and are REACH unaffected. Substitute part selection is justified based on continued availability and matching compliance status.

Frequently Asked Questions (FAQ)

Q1: What determines if KSC945YTA is an equivalent substitute for 2SC1740STPQ?
A1: Equivalence is determined strictly by matching the following parameters: NPN transistor type, 50 V maximum collector-emitter breakdown voltage, 150 mA maximum collector current, collector cutoff current, minimum DC current gain at specified current/voltage, power dissipation, transition frequency, and mechanical compatibility including through hole mounting and package/case type, as well as RoHS and REACH compliance.

Q2: Are there any differences in package or mounting between 2SC1740STPQ and KSC945YTA?
A2: Both parts support through hole mounting. The 2SC1740STPQ uses the SC-72 Formed Leads (SPT) package, while the KSC945YTA utilizes the TO-226-3, TO-92-3 (TO-226AA) Formed Leads (TO-92-3).

Q3: What are the implications of the 2SC1740STPQ being obsolete?
A3: The obsolete status necessitates selection of functionally and mechanically equivalent substitutes for ongoing designs or field replacements. Selection should match all critical parameters and compliance attributes provided.

Q4: Is RoHS and REACH compliance consistent between these parts?
A4: Both 2SC1740STPQ and KSC945YTA are classified as ROHS3 Compliant and REACH Unaffected.

Q5: Are there thermal or electrical performance differences to consider based solely on the given parameters?
A5: From the provided data, differences include a maximum power dissipation of 300 mW for 2SC1740STPQ and 250 mW for KSC945YTA, and a higher frequency transition for KSC945YTA (300 MHz vs 180 MHz for 2SC1740STPQ). These distinctions are documented in parameter comparison.

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