KST06MTF Equivalent & Substitute Parts

Part Overview

The KST06MTF is an NPN bipolar junction transistor manufactured by onsemi, housed in a SOT-23-3 surface mount package. This device is rated for 80 V collector-emitter breakdown voltage and 500 mA maximum collector current, with a maximum power dissipation of 350 mW. The KST06MTF is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements. Substitute parts must maintain electrical and mechanical compatibility within the specified parameter ranges.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	80	V
Current - Collector (Ic) (Max)	500	mA
Power - Max	350	mW
Frequency - Transition	100	MHz
Vce Saturation (Max) @ Ib, Ic	250 mV @ 10 mA, 100 mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	50 @ 100 mA, 1 V	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Mounting Type	Surface Mount	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the KST06MTF is determined by strict electrical and mechanical parameter matching. The critical parameters that define substitutability are:

Electrical Parameters:

Voltage - Collector Emitter Breakdown (Max): 80 V minimum
Current - Collector (Ic) (Max): 500 mA minimum
Power - Max: 350 mW minimum
Vce Saturation (Max) @ Ib, Ic: 250 mV @ 10 mA, 100 mA or lower
DC Current Gain (hFE) (Min) @ Ic, Vce: 50 @ 100 mA, 1 V or higher
Frequency - Transition: 100 MHz minimum

Mechanical Parameters:

Package / Case: TO-236-3, SC-59, SOT-23-3
Mounting Type: Surface Mount
Moisture Sensitivity Level (MSL): 1 (Unlimited)

Substitute parts are grouped into two categories:

Category A - Direct Electrical Equivalents: Parts meeting or exceeding all electrical parameters of the KST06MTF with identical or superior performance characteristics.

Category B - Functional Substitutes: Parts meeting the core electrical requirements (80 V, 500 mA, SOT-23-3 package) with variations in secondary parameters such as transition frequency or saturation voltage, suitable for applications where these variations do not impact circuit performance.

Parameter Comparison

Part Number	Manufacturer	Vce Breakdown (V)	Ic Max (mA)	Power Max (mW)	Vce Sat @ 10mA, 100mA (mV)	hFE Min @ 100mA, 1V	Frequency (MHz)	Package	Product Status
KST06MTF	onsemi	80	500	350	250	50	100	SOT-23-3	Obsolete
MMBT8099LT1G	onsemi	80	500	225	400	100	150	SOT-23-3	Active
MMBTA06LT1G	onsemi	80	500	225	250	100	100	SOT-23-3	Active
MMBTA06LT3G	onsemi	80	500	225	250	100	100	SOT-23-3	Active
SMMBTA06LT1G	onsemi	80	500	225	250	100	100	SOT-23-3	Active
SMMBTA06LT3G	onsemi	80	500	225	250	100	100	SOT-23-3	Active
2SD1782KT146R	Rohm Semiconductor	80	500	200	500	180	120	SOT-23-3	Active
CMPT3019 BK PBFREE	Central Semiconductor Corp	80	500	350	500	100	400	SOT-23-3	Active
CMPT3019 TR PBFREE	Central Semiconductor Corp	80	500	350	500	100	400	SOT-23-3	Active
CMPT8099 TR PBFREE	Central Semiconductor Corp	80	500	350	300	100	150	SOT-23-3	Active
MMBT6429LT1G	onsemi	45	200	225	600	500	700	SOT-23-3	Active

Engineering Selection Recommendations

Primary Substitutes (Recommended for Direct Replacement):

The following parts are recommended as primary substitutes for the KST06MTF based on active product status, full electrical parameter compatibility, and compliance certifications:

MMBTA06LT1G (onsemi) — This part provides direct electrical equivalence with identical Vce saturation characteristics (250 mV @ 10 mA, 100 mA) and matching transition frequency (100 MHz). The part is RoHS3 compliant and available in high volume (2,255,600 units in stock). Packaging is Cut Tape (CT) & Digi-Reel®.

MMBTA06LT3G (onsemi) — Electrically identical to MMBTA06LT1G with the same parameter specifications. Available in Tape & Reel (TR) packaging with 4,934 units in stock. RoHS3 compliant.

SMMBTA06LT1G (onsemi) — Provides identical electrical performance to MMBTA06LT1G and MMBTA06LT3G. Available in Tape & Reel (TR) packaging with 206,300 units in stock. RoHS3 compliant.

SMMBTA06LT3G (onsemi) — Electrically equivalent to other SMMBTA06 variants. Available in Tape & Reel (TR) packaging with 20,200 units in stock. RoHS3 compliant.

Secondary Substitutes (Acceptable with Application Review):

MMBT8099LT1G (onsemi) — Meets all core electrical requirements (80 V, 500 mA, SOT-23-3). Vce saturation is higher at 400 mV (versus 250 mV), and transition frequency is elevated at 150 MHz. Suitable for applications where higher saturation voltage and frequency are acceptable. RoHS3 compliant. 20,100 units in stock.

CMPT8099 TR PBFREE (Central Semiconductor Corp) — Meets all core electrical requirements with Vce saturation of 300 mV and transition frequency of 150 MHz. Power dissipation matches the original at 350 mW. RoHS3 compliant. 5,407 units in stock.

CMPT3019 BK PBFREE and CMPT3019 TR PBFREE (Central Semiconductor Corp) — Both variants meet core electrical requirements with 350 mW power dissipation matching the original. Transition frequency is elevated at 400 MHz. Vce saturation is 500 mV, which is higher than the original. RoHS3 compliant. 996 units (bulk) and 19,215 units (tape & reel) in stock.

Not Recommended:

MMBT6429LT1G (onsemi) — This part does not meet the electrical requirements of the KST06MTF. Maximum collector current is limited to 200 mA (versus 500 mA required), and collector-emitter breakdown voltage is only 45 V (versus 80 V required). This part is suitable only for applications with significantly lower voltage and current requirements.

2SD1782KT146R (Rohm Semiconductor) — While this part meets the core voltage and current requirements, the Vce saturation of 500 mV is significantly higher than the original 250 mV specification, and power dissipation is reduced to 200 mW. This part is suitable only for applications where higher saturation voltage and lower power dissipation are acceptable.

Frequently Asked Questions (FAQ)

Q: Why is the KST06MTF obsolete, and what does this mean for my design?

A: The KST06MTF has been discontinued by onsemi. Obsolete status means the manufacturer no longer produces this part. Existing inventory may be available from distributors, but long-term supply cannot be guaranteed. For new designs and ongoing production, selection of an active substitute part is necessary to ensure supply chain continuity.

Q: What are the minimum electrical requirements for a substitute part?

A: A substitute part must meet or exceed the following parameters: 80 V collector-emitter breakdown voltage, 500 mA maximum collector current, 350 mW maximum power dissipation, 250 mV maximum Vce saturation at 10 mA and 100 mA, 50 minimum DC current gain at 100 mA and 1 V, and 100 MHz minimum transition frequency. The part must also be housed in a SOT-23-3 surface mount package.

Q: Can I use MMBT6429LT1G as a substitute?

A: No. The MMBT6429LT1G is not suitable as a substitute for the KST06MTF. This part is rated for only 45 V collector-emitter breakdown voltage and 200 mA maximum collector current, both significantly below the KST06MTF requirements. Use of this part would result in circuit failure or reduced performance.

Q: What is the difference between MMBTA06LT1G and MMBTA06LT3G?

A: Both parts are electrically identical with the same electrical specifications. The difference is in the packaging format: MMBTA06LT1G is supplied in Cut Tape (CT) & Digi-Reel® format, while MMBTA06LT3G is supplied in Tape & Reel (TR) format. Selection between these variants depends on your procurement and assembly process requirements.

Q: Why do some substitute parts have lower power dissipation ratings than the original?

A: Several substitute parts (MMBT8099LT1G, MMBTA06LT1G, MMBTA06LT3G, SMMBTA06LT1G, SMMBTA06LT3G) are rated for 225 mW maximum power dissipation, compared to the original 350 mW. This reduction does not affect substitutability if your circuit design operates within the 225 mW limit. The lower rating reflects improved thermal characteristics of the newer device design. If your application requires the full 350 mW dissipation capability, select CMPT3019 variants or CMPT8099 TR PBFREE.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed in this document are RoHS3 compliant. The original KST06MTF does not have RoHS status specified, but all active alternatives meet current RoHS3 requirements.

Q: What is the difference between onsemi and Central Semiconductor Corp substitutes?

A: Both manufacturers provide functionally equivalent parts in the SOT-23-3 package. onsemi substitutes (MMBTA06 and SMMBTA06 series) offer the closest electrical match to the original KST06MTF. Central Semiconductor Corp substitutes (CMPT3019 and CMPT8099 series) provide equivalent functionality with variations in transition frequency and saturation voltage. Selection depends on availability, pricing, and specific application requirements.

Q: Can I mix different substitute parts in the same circuit board?

A: Yes, provided all selected parts meet the minimum electrical requirements for your circuit. However, for consistency in manufacturing and testing, it is recommended to standardize on a single substitute part number per design.

Q: What is the Moisture Sensitivity Level (MSL), and why is it important?

A: MSL indicates the moisture absorption characteristics of the component and the handling precautions required during storage and assembly. All parts listed, including the original KST06MTF, have MSL 1 (Unlimited), meaning they have unlimited shelf life and require no special moisture control during storage or handling.

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