30BQ040 Equivalent & Substitute Parts

Part Overview

The 30BQ040 is a Schottky rectifier diode rated for 40 V DC reverse voltage and 3 A average rectified current in a DO-214AB (SMC) surface mount package. Manufactured by Vishay General Semiconductor - Diodes Division, this component is classified as obsolete. Due to its obsolete status and limited availability relative to active alternatives, equivalent substitute parts from active manufacturers are necessary for new designs and ongoing production requirements. Substitute diodes must maintain electrical compatibility across voltage, current, and thermal specifications while meeting modern compliance standards.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	40	V
Current - Average Rectified (Io)	3	A
Voltage - Forward (Vf) (Max) @ If	530 mV @ 3 A	mV
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	ns
Current - Reverse Leakage @ Vr	500 µA @ 40 V	µA
Mounting Type	Surface Mount	—
Package / Case	DO-214AB, SMC	—
Operating Temperature - Junction	-55°C ~ 150°C	°C
Technology	Schottky	—

Substitute Part Grouping Explanation

Substitute parts for the 30BQ040 are selected based on strict electrical and mechanical parameter matching. The primary substitution criteria are:

Mandatory Matching Parameters:

Voltage - DC Reverse (Vr) (Max): 40 V minimum
Current - Average Rectified (Io): 3 A minimum
Technology: Schottky
Mounting Type: Surface Mount
Package / Case: DO-214AB or SMC equivalent
Speed: Fast Recovery ≤ 500ns, > 200mA (Io)

Acceptable Parameter Variations:

Forward Voltage (Vf): Substitute parts may have Vf values between 500 mV and 630 mV at rated current without functional impact
Reverse Leakage Current: Values between 20 µA and 2 mA at rated voltage are acceptable
Operating Temperature Range: Minimum junction temperature may vary; maximum must not be lower than 125°C
RoHS Compliance: Active substitutes must meet ROHS3 compliance

Substitute parts are grouped into two categories: Direct Equivalents (40 V, 3 A rating) and Upgraded Alternatives (higher voltage or current ratings that maintain backward compatibility).

Parameter Comparison

Part Number	Manufacturer	Vr (Max) [V]	Io [A]	Vf (Max) @ If [mV]	Reverse Leakage @ Vr [µA]	Tj (Max) [°C]	Product Status	RoHS Status
30BQ040	Vishay	40	3	530 @ 3A	500 @ 40V	150	Obsolete	Non-compliant
B340-13-F	Diodes Inc.	40	3	500 @ 3A	500 @ 40V	125	Active	ROHS3
CDBC340-G	Comchip	40	3	500 @ 3A	500 @ 40V	125	Active	ROHS3
MBRS340T3G	onsemi	40	3	500 @ 3A	2000 @ 40V	150	Active	ROHS3
SBRS8340T3G	onsemi	40	3	500 @ 3A	2000 @ 40V	150	Active	ROHS3
STPS340S	STMicroelectronics	40	3	630 @ 3A	20 @ 40V	150	Active	ROHS3
STPS340SY	STMicroelectronics	40	3	630 @ 3A	20 @ 40V	150	Active	ROHS3
STPS3L40S	STMicroelectronics	40	3	500 @ 3A	100 @ 40V	150	Active	ROHS3
STPS3L40SY	STMicroelectronics	40	3	500 @ 3A	100 @ 40V	150	Active	ROHS3
MBRS540T3G	onsemi	40	5	500 @ 5A	300 @ 40V	150	Active	ROHS3
B550C-13-F	Diodes Inc.	50	5	700 @ 5A	500 @ 50V	150	Active	ROHS3

Engineering Selection Recommendations

Direct Equivalents (40 V, 3 A Rating):

The following parts provide direct electrical equivalence to the 30BQ040 with identical voltage and current ratings:

B340-13-F (Diodes Incorporated): Active product with ROHS3 compliance. Forward voltage of 500 mV at 3 A provides improved efficiency compared to the original 530 mV specification. Maximum junction temperature of 125°C is acceptable for most applications within the original -55°C to 150°C operating range.
CDBC340-G (Comchip Technology): Active product with ROHS3 compliance. Electrical characteristics match B340-13-F. Lower inventory availability (3,700 units) compared to other alternatives.
MBRS340T3G (onsemi): Active product with ROHS3 compliance. Maintains 150°C maximum junction temperature matching the original part. Extended temperature range (-65°C to 150°C) provides additional margin. Higher reverse leakage current (2 mA) is within acceptable limits.
SBRS8340T3G (onsemi): Active product with ROHS3 compliance and AEC-Q101 automotive qualification. Identical electrical specifications to MBRS340T3G. Suitable for automotive applications requiring formal qualification.
STPS340S (STMicroelectronics): Active product with ROHS3 compliance. Forward voltage of 630 mV at 3 A represents the upper acceptable limit. Reverse leakage of 20 µA is significantly lower than the original specification, indicating superior leakage performance.
STPS340SY (STMicroelectronics): Active product with ROHS3 compliance and AEC-Q101 automotive qualification. Identical electrical specifications to STPS340S with automotive-grade qualification. Operating temperature range of -40°C to 150°C.
STPS3L40S (STMicroelectronics): Active product with ROHS3 compliance. Forward voltage of 500 mV at 3 A provides improved efficiency. Reverse leakage of 100 µA is moderate. Maximum junction temperature of 150°C matches the original part.
STPS3L40SY (STMicroelectronics): Active product with ROHS3 compliance and automotive-grade designation. Identical electrical specifications to STPS3L40S with extended operating temperature range (-40°C to 150°C).

Upgraded Alternatives (Higher Current Rating):

MBRS540T3G (onsemi): 40 V, 5 A rating provides current margin above the original 3 A specification. Active product with ROHS3 compliance. Suitable for applications requiring higher current capacity while maintaining the same voltage rating.

Upgraded Alternative (Higher Voltage and Current Rating):

B550C-13-F (Diodes Incorporated): 50 V, 5 A rating provides both voltage and current margin. Active product with ROHS3 compliance. Suitable for applications where higher voltage and current headroom are beneficial. Forward voltage of 700 mV at 5 A reflects the higher current rating.

All substitute parts are available in DO-214AB (SMC) surface mount package, ensuring mechanical compatibility with the original 30BQ040 footprint.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with a higher voltage rating than the 30BQ040?

A: Yes. A substitute part with a higher maximum reverse voltage (such as B550C-13-F at 50 V) is electrically compatible with applications designed for 40 V operation. The higher voltage rating provides additional safety margin and does not degrade performance in 40 V circuits.

Q: What is the difference between STPS340S and STPS340SY?

A: Both parts have identical electrical specifications (40 V, 3 A, 630 mV forward voltage). STPS340SY includes AEC-Q101 automotive qualification and operates over -40°C to 150°C, while STPS340S has a maximum junction temperature specification of 150°C without automotive qualification. STPS340SY is required for automotive applications.

Q: Can I use MBRS540T3G (5 A) in place of the 30BQ040 (3 A)?

A: Yes. MBRS540T3G is rated for 5 A average rectified current, which exceeds the 3 A requirement of the original part. The 40 V voltage rating matches exactly. This part is suitable for applications where higher current capacity is needed or where design margin is desired.

Q: Why do some substitute parts have lower forward voltage than the 30BQ040?

A: Forward voltage variation is a normal characteristic of Schottky diodes and depends on manufacturing process and design. Parts with lower forward voltage (such as B340-13-F at 500 mV versus the original 530 mV) provide improved efficiency and reduced power dissipation. This is a beneficial characteristic and does not indicate incompatibility.

Q: Are all substitute parts RoHS compliant?

A: Yes. All active substitute parts listed are ROHS3 compliant. The original 30BQ040 is marked as RoHS non-compliant due to its obsolete status. Substitution with ROHS3-compliant parts is necessary for compliance with current environmental regulations.

Q: What is the difference between STPS3L40S and STPS340S?

A: Both parts are rated 40 V, 3 A in DO-214AB (SMC) package. STPS3L40S has a forward voltage of 500 mV at 3 A and reverse leakage of 100 µA, while STPS340S has a forward voltage of 630 mV and reverse leakage of 20 µA. STPS340S exhibits lower leakage current; STPS3L40S provides lower forward voltage and improved efficiency.

Q: Can I substitute the 30BQ040 with B550C-13-F in a 40 V circuit?

A: Yes. B550C-13-F is rated for 50 V maximum reverse voltage, which is compatible with 40 V circuit operation. The higher voltage rating provides additional safety margin. The 5 A current rating also exceeds the 3 A requirement. This part is suitable for applications where higher voltage and current headroom are beneficial.

Q: What does "Fast Recovery ≤ 500ns, > 200mA (Io)" mean?

A: This specification indicates that the diode exhibits fast recovery characteristics with a recovery time of 500 nanoseconds or less when switching currents greater than 200 mA. All listed substitute parts meet this specification, ensuring compatibility with high-frequency switching applications.

Q: Is SBRS8340T3G suitable for non-automotive applications?

A: Yes. SBRS8340T3G is qualified to AEC-Q101 automotive standards, but this qualification does not restrict its use in non-automotive applications. It provides identical electrical performance to MBRS340T3G with additional quality assurance documentation. It is suitable for any application requiring 40 V, 3 A Schottky rectification.

Q: What is the significance of the DO-214AB (SMC) package designation?

A: DO-214AB and SMC (Surface Mount Case) refer to the same physical package. All substitute parts use this identical package, ensuring direct mechanical compatibility with the original 30BQ040 footprint. No PCB layout modifications are required for substitution.

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