FMMTH10TC RF Transistor NPN Equivalent & Substitute Parts

Part Overview

The FMMTH10TC is an RF transistor NPN manufactured by Diodes Incorporated, designed for RF applications operating at 650MHz with a maximum collector-emitter breakdown voltage of 25V and power dissipation of 330mW in a surface mount SOT-23-3 package. The device is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and procurement needs. This reference provides direct substitutes and functional equivalents based on electrical and mechanical compatibility parameters.

Key Parameters

Parameter	FMMTH10TC Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	25V	V
Frequency - Transition	650MHz	MHz
Noise Figure (Typ @ f)	3dB ~ 5dB @ 500MHz	dB
Power - Max	330mW	mW
DC Current Gain (hFE) (Min) @ Ic, Vce	60 @ 4mA, 10V	—
Current - Collector (Ic) (Max)	25mA	mA
Operating Temperature	-55°C ~ 150°C (TJ)	°C
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the FMMTH10TC is determined by the following critical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (required match)
Voltage - Collector Emitter Breakdown (Max): 25V or greater (must support or exceed)
Frequency - Transition: 650MHz or greater (must support or exceed)
Package / Case: SOT-23-3 compatible form factor (mechanical compatibility)
Mounting Type: Surface Mount (required match)
Operating Temperature Range: -55°C to 150°C or compatible subset
RoHS Status: ROHS3 Compliant (regulatory requirement)
Moisture Sensitivity Level: 1 (Unlimited) or equivalent

Secondary Compatibility Parameters:

DC Current Gain (hFE): 60 @ 4mA, 10V or functionally equivalent
Current - Collector (Ic) (Max): 25mA or greater
Power - Max: 330mW or greater

Substitutes are grouped into two categories:

Category A - Direct Package Equivalents (SOT-23-3): Parts maintaining identical or pin-compatible package geometry, enabling direct board-level replacement without layout modification.

Category B - Functional Equivalents (Alternative Packages): Parts meeting or exceeding all electrical parameters but utilizing different surface mount packages, requiring board redesign or adapter consideration.

Parameter Comparison

Part Number	Manufacturer	Transistor Type	Vce (Max) [V]	Frequency [MHz/GHz]	Power (Max) [mW]	hFE (Min) @ Ic, Vce	Ic (Max) [mA]	Package	Product Status
FMMTH10TC	Diodes Incorporated	NPN	25	650	330	60 @ 4mA, 10V	25	SOT-23-3	Obsolete
MMBTH10LT1G	onsemi	NPN	25	650	225	60 @ 4mA, 10V	—	SOT-23-3	Active
MMBTH10LT3G	onsemi	NPN	25	650	225	60 @ 4mA, 10V	—	SOT-23-3	Active
MMBTH10-4LT1G	onsemi	NPN	25	800	225	120 @ 4mA, 10V	—	SOT-23-3	Active
KST10MTF	onsemi	NPN	25	650	350	60 @ 4mA, 10V	—	SOT-23-3	Active
MMBT5179	onsemi	NPN	12	2000	225	25 @ 3mA, 1V	50	SOT-23-3	Active
NSVF4009SG4T1G	onsemi	NPN	3.5	25000	120	50 @ 5mA, 1V	40	SC-82FL/MCPH4	Active
BFP405FH6327XTSA1	Infineon Technologies	NPN	4.5	25000	75	60 @ 5mA, 4V	25	4-TSFP	Active
BFP620FH7764XTSA1	Infineon Technologies	NPN	2.8	65000	185	110 @ 50mA, 1.5V	80	4-TSFP	Active
BFP720ESDH6327XTSA1	Infineon Technologies	NPN	4.7	43000	100	160 @ 15mA, 3V	30	SOT-343	Active
BFU690F,115	NXP USA Inc.	NPN	5.5	18000	230	90 @ 20mA, 2V	100	SOT-343F	Active

Engineering Selection Recommendations

Direct Replacement (Same Package - SOT-23-3):

The following parts are recommended as direct replacements for the FMMTH10TC in existing designs without board layout modification:

MMBTH10LT1G (onsemi) - Identical electrical specifications at 650MHz, 25V Vce, matching hFE of 60 @ 4mA, 10V. Active product status with unlimited MSL and ROHS3 compliance. Suitable for direct pin-compatible substitution.
MMBTH10LT3G (onsemi) - Identical to MMBTH10LT1G with equivalent electrical performance. Tape & Reel packaging option. Active product status with full compliance certifications.
MMBTH10-4LT1G (onsemi) - Enhanced frequency capability at 800MHz with increased hFE of 120 @ 4mA, 10V. Maintains 25V Vce rating and SOT-23-3 package. Active product status. Suitable where higher frequency margin is required.
KST10MTF (onsemi) - Exceeds power dissipation specification at 350mW versus 330mW original. Maintains 25V Vce, 650MHz frequency, and hFE of 60 @ 4mA, 10V. Active product status with full compliance. Recommended for applications requiring higher power margin.

Functional Equivalents (Alternative Packages):

The following parts meet or exceed electrical specifications but require board redesign due to package differences:

NSVF4009SG4T1G (onsemi) - Automotive-qualified RF transistor with 25GHz frequency capability, 3.5V Vce, and SC-82FL/MCPH4 package. Exceeds frequency requirements significantly. AEC-Q101 qualified. Suitable for automotive RF applications requiring higher frequency performance.
BFP720ESDH6327XTSA1 (Infineon Technologies) - High-frequency RF transistor at 43GHz with 4.7V Vce and SOT-343 package. Exceeds frequency and power specifications. Active product status with ROHS3 compliance. Suitable for applications requiring significantly higher frequency operation.
BFU690F,115 (NXP USA Inc.) - RF transistor at 18GHz with 5.5V Vce and SOT-343F package. Exceeds frequency capability with 100mA collector current. Active product status with full compliance. Suitable for higher current RF applications.

Not Recommended for Direct Substitution:

MMBT5179 - Voltage rating of 12V is insufficient for 25V Vce requirement. Frequency capability of 2GHz exceeds application needs but voltage limitation precludes use.
BFP405FH6327XTSA1 - Voltage rating of 4.5V is insufficient for 25V Vce requirement.
BFP620FH7764XTSA1 - Voltage rating of 2.8V is insufficient for 25V Vce requirement.

Frequently Asked Questions (FAQ)

Q: Can MMBTH10LT1G directly replace FMMTH10TC without board modification?

A: Yes. MMBTH10LT1G maintains identical SOT-23-3 package geometry, pin configuration, and electrical specifications at 650MHz and 25V Vce with matching hFE of 60 @ 4mA, 10V. Direct pin-for-pin substitution is supported.

Q: What is the difference between MMBTH10LT1G and MMBTH10LT3G?

A: Both parts are electrically identical with 650MHz frequency, 25V Vce, and hFE of 60 @ 4mA, 10V. The primary difference is packaging format: MMBTH10LT1G is supplied in Cut Tape (CT) & Digi-Reel format, while MMBTH10LT3G is supplied in Tape & Reel (TR) format. Selection depends on procurement and assembly requirements.

Q: Why is MMBTH10-4LT1G listed as a substitute if it has different frequency and hFE specifications?

A: MMBTH10-4LT1G operates at 800MHz versus the original 650MHz, providing higher frequency margin. The hFE of 120 @ 4mA, 10V is double the original specification, which may affect circuit biasing. This part is suitable for applications where higher frequency capability is beneficial and circuit design accommodates the increased gain. Electrical characterization is required for specific applications.

Q: Can parts with lower voltage ratings like BFP405FH6327XTSA1 (4.5V) be used?

A: No. The FMMTH10TC specifies a maximum collector-emitter breakdown voltage of 25V. Substitutes must meet or exceed this voltage rating. Parts with lower voltage ratings will fail under the specified operating conditions and are not acceptable substitutes.

Q: What is the significance of the SOT-343 package alternatives?

A: SOT-343 is a smaller surface mount package compared to SOT-23-3. Parts in SOT-343 packages (BFP720ESDH6327XTSA1, BFU690F,115) require board layout redesign and cannot be used as direct pin-compatible replacements. These are functional equivalents suitable only for new designs or boards with modified layouts.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance status, matching the original FMMTH10TC specification. All parts also maintain Moisture Sensitivity Level 1 (Unlimited) and REACH Unaffected status.

Q: Which substitute offers the best power dissipation margin?

A: KST10MTF provides the highest power rating at 350mW compared to the original 330mW specification, offering approximately 6% additional margin while maintaining identical frequency, voltage, and gain specifications in the same SOT-23-3 package.

Q: Can NSVF4009SG4T1G be used in non-automotive applications?

A: NSVF4009SG4T1G is automotive-qualified (AEC-Q101) and can be used in non-automotive applications. However, its 3.5V Vce rating is insufficient for the 25V requirement of the FMMTH10TC, making it unsuitable regardless of application classification.

Q: What inventory considerations apply to these substitutes?

A: Inventory availability varies significantly. MMBTH10LT1G has 62,400 pieces in stock, KST10MTF has 391,101 pieces, and MMBTH10-4LT1G has 18,400 pieces, providing strong supply continuity. Higher-frequency alternatives (BFP series, BFU690F) have lower inventory levels (3,855 to 5,367 pieces), which may impact procurement timelines for high-volume requirements.

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