BSR57,215 N-Channel JFET Equivalent & Substitute Parts

Part Overview

The BSR57,215 is an N-Channel JFET manufactured by NXP USA Inc., rated for 40 V drain-to-source voltage with 250 mW maximum power dissipation in a surface mount SOT-23 package. This part is classified as obsolete, making substitute components necessary for new designs and ongoing production requirements. Equivalent parts must maintain compatibility across electrical performance parameters, mechanical packaging, and thermal characteristics to ensure direct circuit functionality.

Key Parameters

Parameter	BSR57,215 Value	Unit
FET Type	N-Channel	—
Voltage - Breakdown (V(BR)GSS)	40	V
Drain to Source Voltage (Vdss)	40	V
Current - Drain (Idss) @ Vds (Vgs=0)	20 mA @ 15 V	mA
Voltage - Cutoff (VGS off) @ Id	5 V @ 0.5 nA	V
Resistance - RDS(On)	40	Ohms
Power - Max	250	mW
Operating Temperature	150	°C (TJ)
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the BSR57,215 is determined by the following criteria:

Primary Matching Parameters:

FET Type: N-Channel (required)
Package / Case: TO-236-3, SC-59, or SOT-23-3 (required for mechanical compatibility)
Mounting Type: Surface Mount (required)
Voltage - Breakdown (V(BR)GSS): 40 V minimum (electrical safety requirement)
Drain to Source Voltage (Vdss): 40 V minimum (circuit voltage rating)
Power - Max: 250 mW minimum (thermal capability)
RoHS Status: ROHS3 Compliant (regulatory requirement)
Moisture Sensitivity Level (MSL): 1 (Unlimited) (handling and storage compatibility)

Substitute parts are grouped into two categories based on drain current (Idss) characteristics:

Category A - High Drain Current (Idss ≥ 8 mA): Parts suitable for applications requiring moderate to high drain current performance. Includes BSR57, BSR58, MMBF4093, MMBF5103, MMBFJ202, and 2SK209-GR(TE85L,F).

Category B - Low Drain Current (Idss < 8 mA): Parts suitable for applications requiring minimal drain current or precision biasing. Includes 2SK545-11D-TB-E, MMBF4117, and MMBFJ201.

Category C - Reduced Voltage Rating (Vdss = 30 V): Part MMBF4391LT1G operates at 30 V, suitable only for circuits with lower voltage requirements.

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Idss @ Vds (mA)	VGS off (V)	RDS(On) (Ω)	Power Max (mW)	Temp Range (°C)	Status
BSR57,215	NXP USA Inc.	40	20 @ 15V	5 @ 0.5nA	40	250	150	Obsolete
BSR57	onsemi	40	20 @ 15V	2 @ 0.5nA	40	250	150	Active
BSR58	onsemi	40	8 @ 15V	0.8 @ 0.5nA	60	250	150	Active
MMBF4093	onsemi	40	8 @ 20V	1 @ 1nA	80	350	-55 to 150	Active
MMBF4117	onsemi	40	0.03 @ 10V	0.6 @ 1nA	—	225	-55 to 150	Active
MMBF4391LT1G	onsemi	30	50 @ 15V	4 @ 10nA	30	225	-55 to 150	Active
MMBF5103	onsemi	40	10 @ 15V	1.2 @ 1nA	—	350	-55 to 150	Active
MMBFJ201	onsemi	40	0.2 @ 20V	0.3 @ 10nA	—	350	-55 to 150	Active
MMBFJ202	onsemi	40	0.9 @ 20V	0.8 @ 10nA	—	350	-55 to 150	Active
2SK209-GR(TE85L,F)	Toshiba Semiconductor and Storage	50	14 @ 10V	1.5 @ 100nA	—	150	125	Active
2SK545-11D-TB-E	onsemi	40	0.06 @ 10V	1.5 @ 1µA	—	125	—	Obsolete

Engineering Selection Recommendations

Primary Substitute (Direct Replacement): BSR57 (onsemi) is the recommended primary substitute. It maintains identical electrical specifications to BSR57,215 (40 V Vdss, 20 mA Idss, 40 Ω RDS(On), 250 mW power rating) with active product status, ROHS3 compliance, and unlimited MSL rating. The only parameter variance is VGS off (2 V vs. 5 V), which does not affect circuit functionality in standard applications.

Secondary Substitutes (Category A - High Drain Current):

MMBF4093: Meets all voltage and package requirements with higher power rating (350 mW) and extended temperature range (-55°C to 150°C). Idss of 8 mA is lower than BSR57,215; suitable for applications tolerating reduced drain current.
MMBF5103: Provides 40 V rating, 350 mW power, and extended temperature range. Idss of 10 mA is acceptable for moderate drain current applications.
MMBFJ202: Offers 40 V rating and 350 mW power with extended temperature range. Idss of 0.9 mA is significantly lower; use only in low-current biasing circuits.
2SK209-GR(TE85L,F): Toshiba part with 50 V rating (exceeds requirement) and 14 mA Idss. Power rating of 150 mW is below BSR57,215; verify thermal requirements before selection.

Secondary Substitutes (Category B - Low Drain Current):

MMBF4117: Extreme low drain current (30 µA) with 40 V rating and 225 mW power. Use only in precision biasing or high-impedance applications.
MMBFJ201: Ultra-low drain current (200 µA) with 40 V rating and 350 mW power. Suitable for precision gate biasing circuits.

Voltage-Reduced Substitute (Category C):

MMBF4391LT1G: 30 V Vdss rating is below BSR57,215 specification. Use only in circuits with maximum operating voltage of 30 V or lower.

Obsolete Parts (Not Recommended for New Designs):

2SK545-11D-TB-E: Obsolete status; avoid for new production unless existing inventory is available and circuit requirements are met.

Frequently Asked Questions (FAQ)

Q: Can BSR57 directly replace BSR57,215 in all applications? A: Yes. BSR57 maintains identical voltage ratings (40 V), drain current (20 mA), on-resistance (40 Ω), and power dissipation (250 mW). The VGS off parameter difference (2 V vs. 5 V) does not affect standard circuit operation. BSR57 is the recommended direct replacement.

Q: What is the difference between Category A and Category B substitutes? A: Category A parts (MMBF4093, MMBF5103, MMBFJ202, 2SK209) have drain current (Idss) of 8 mA or higher, suitable for applications requiring moderate to high drain current performance. Category B parts (MMBF4117, MMBFJ201) have drain current below 8 mA, designed for low-current biasing or precision applications. Selection depends on circuit drain current requirements.

Q: Why does MMBF4391LT1G have a lower voltage rating (30 V)? A: MMBF4391LT1G is designed for lower-voltage applications. Its 30 V Vdss rating is insufficient for circuits requiring 40 V operation. Use this part only if your circuit maximum voltage is 30 V or lower.

Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts are ROHS3 compliant and carry unlimited MSL (Moisture Sensitivity Level 1), matching BSR57,215 environmental and regulatory requirements.

Q: What is the impact of different power ratings among substitutes? A: BSR57,215 is rated for 250 mW. Substitutes with higher power ratings (MMBF4093, MMBF5103, MMBFJ201, MMBFJ202 at 350 mW) provide additional thermal margin. The 2SK209-GR(TE85L,F) at 150 mW is lower; verify that circuit power dissipation does not exceed this limit. BSR58 and MMBF4117 at 225 mW are acceptable for most applications.

Q: Can I use 2SK209-GR(TE85L,F) as a substitute despite its lower power rating? A: Only if circuit analysis confirms power dissipation remains below 150 mW. The 2SK209 also has a higher Vdss rating (50 V), which is acceptable. However, the reduced power budget may limit thermal performance in high-dissipation circuits.

Q: What packaging considerations apply to these substitutes? A: All substitute parts use TO-236-3, SC-59, or SOT-23-3 surface mount packages, maintaining mechanical compatibility with BSR57,215. Verify PCB footprint and reflow profile compatibility with your manufacturing process.

Q: Should I avoid obsolete parts like 2SK545-11D-TB-E? A: For new designs, use active parts (BSR57, MMBF4093, MMBF5103, MMBFJ201, MMBFJ202, 2SK209-GR(TE85L,F)). Obsolete parts are acceptable only if existing inventory is available and circuit requirements are met. Verify long-term supply availability before committing to obsolete components.

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