BST50-QX Equivalent & Substitute Parts

Part Overview

The BST50-QX is an NPN Darlington bipolar junction transistor manufactured by Nexperia USA Inc. in an SOT-89 surface mount package. This component is designed for applications requiring moderate current amplification with a maximum collector current of 1 A and collector-emitter breakdown voltage of 45 V. The part is currently in active production status with 898 pieces available in new original inventory. Substitute parts are identified when equivalent electrical and mechanical parameters are required for design flexibility, inventory management, or supply chain continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN - Darlington	—
Current - Collector (Ic) (Max)	1	A
Voltage - Collector Emitter Breakdown (Max)	45	V
Vce Saturation (Max) @ Ib, Ic	1.3V @ 500µA, 500mA	V
Current - Collector Cutoff (Max)	50	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	2000 @ 500mA, 10V	—
Power - Max	1.3	W
Frequency - Transition	200	MHz
Operating Temperature (TJ)	150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-243AA	—
Supplier Device Package	SOT-89	—
RoHS Status	ROHS3 Compliant	—
REACH Status	REACH Unaffected	—

Substitute Part Grouping Explanation

Substitute parts for the BST50-QX are identified based on electrical and mechanical parameter equivalence. The substitution logic is based on the following criteria:

Electrical Parameters (Must Match):

Transistor Type: NPN - Darlington
Maximum Collector Current (Ic): 1 A
Collector-Emitter Breakdown Voltage: 45 V
Vce Saturation: 1.3V @ 500µA, 500mA
Collector Cutoff Current: 50 nA
DC Current Gain (hFE): 2000 @ 500mA, 10V
Maximum Power Dissipation: 1.3 W
Transition Frequency: 200 MHz
Operating Temperature: 150°C (TJ)

Mechanical Parameters (Must Match):

Mounting Type: Surface Mount
Package / Case: TO-243AA
Supplier Device Package: SOT-89
Tape & Reel (TR) Packaging

Compliance Parameters:

RoHS3 Compliant
REACH Unaffected

Parts meeting all these criteria are classified as parametric equivalents and direct substitutes.

Parameter Comparison

Parameter	BST50-QX	BST50,115	Match
Manufacturer	Nexperia USA Inc.	Nexperia USA Inc.	✓
Transistor Type	NPN - Darlington	NPN - Darlington	✓
Current - Collector (Ic) (Max)	1 A	1 A	✓
Voltage - Collector Emitter Breakdown (Max)	45 V	45 V	✓
Vce Saturation (Max) @ Ib, Ic	1.3V @ 500µA, 500mA	1.3V @ 500µA, 500mA	✓
Current - Collector Cutoff (Max)	50 nA	50 nA	✓
DC Current Gain (hFE) (Min) @ Ic, Vce	2000 @ 500mA, 10V	2000 @ 500mA, 10V	✓
Power - Max	1.3 W	1.3 W	✓
Frequency - Transition	200 MHz	200 MHz	✓
Operating Temperature (TJ)	150°C	150°C	✓
Mounting Type	Surface Mount	Surface Mount	✓
Package / Case	TO-243AA	TO-243AA	✓
Supplier Device Package	SOT-89	SOT-89	✓
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	✓
REACH Status	REACH Unaffected	REACH Unaffected	✓

Engineering Selection Recommendations

BST50-QX (Primary Part)

The BST50-QX is the standard reference part for this substitution group. It is manufactured by Nexperia USA Inc. and maintains active production status. This part is ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements. Current inventory availability is 898 pieces.

BST50,115 (Parametric Equivalent)

The BST50,115 is a direct parametric equivalent to the BST50-QX. All electrical characteristics, mechanical specifications, and package dimensions are identical. This part carries automotive-grade qualification (AEC-Q101) and is rated for automotive applications. Moisture Sensitivity Level (MSL) is 1 (Unlimited), indicating superior moisture resistance. Current inventory availability is 2220 pieces, providing greater supply availability. The BST50,115 is suitable for applications where automotive-grade components are required or preferred, or where higher inventory levels are advantageous.

Both parts are interchangeable at the circuit level when all electrical and mechanical parameters are equivalent. Selection between these parts should be based on application requirements (automotive vs. general industrial), inventory availability, and supply chain considerations.

Frequently Asked Questions (FAQ)

Q: Can BST50,115 be used as a direct replacement for BST50-QX?

A: Yes. The BST50,115 is a parametric equivalent with identical electrical characteristics (1 A collector current, 45 V breakdown voltage, 1.3 V saturation voltage, 2000 hFE, 200 MHz transition frequency, 1.3 W power rating) and mechanical specifications (SOT-89 package, TO-243AA case, surface mount). Both parts are manufactured by Nexperia USA Inc. and meet ROHS3 and REACH compliance requirements.

Q: What is the difference between BST50-QX and BST50,115?

A: The primary differences are: (1) BST50,115 carries AEC-Q101 automotive qualification, making it suitable for automotive applications; (2) BST50,115 has MSL 1 (Unlimited) moisture sensitivity rating compared to unspecified MSL for BST50-QX; (3) BST50,115 has higher inventory availability (2220 pieces vs. 898 pieces). All electrical and mechanical parameters are identical.

Q: Are these parts pin-compatible?

A: Yes. Both BST50-QX and BST50,115 use the SOT-89 package (TO-243AA case) with identical pinout and mechanical dimensions. No PCB layout modifications are required for substitution.

Q: Can these parts be used interchangeably in automotive applications?

A: The BST50,115 is qualified for automotive use (AEC-Q101). The BST50-QX does not carry automotive qualification. For automotive applications, BST50,115 is the appropriate selection.

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

A: Substitution eligibility is determined by matching: collector current rating (1 A), collector-emitter breakdown voltage (45 V), saturation voltage (1.3V @ 500µA, 500mA), collector cutoff current (50 nA), DC current gain (2000 @ 500mA, 10V), power dissipation (1.3 W), and transition frequency (200 MHz).

Q: Are both parts RoHS and REACH compliant?

A: Yes. Both BST50-QX and BST50,115 are ROHS3 compliant and REACH unaffected, meeting current environmental regulations for electronic components.

Q: What is the operating temperature range for these transistors?

A: Both parts are rated for a maximum junction temperature (TJ) of 150°C. This specification defines the thermal operating limit for the device.

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