SK15-13 Schottky Diode Equivalent & Substitute Parts

Part Overview

The SK15-13 is a Schottky rectifier diode manufactured by Diodes Incorporated, rated for 50 V DC reverse voltage and 1 A average rectified current in a surface mount SMB (DO-214AA) package. This component is discontinued at DiGi Electronics and classified as not recommended for new designs. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this diode specification.

Key Parameters

Parameter	Value
Manufacturer Part Number	SK15-13
Manufacturer	Diodes Incorporated
Category	Diodes, Rectifiers
Technology	Schottky
Voltage - DC Reverse (Vr) (Max)	50 V
Current - Average Rectified (Io)	1 A
Voltage - Forward (Vf) (Max) @ If	700 mV @ 1 A
Speed	Fast Recovery ≤ 500 ns, > 200 mA (Io)
Current - Reverse Leakage @ Vr	500 µA @ 50 V
Package / Case	DO-214AA, SMB
Mounting Type	Surface Mount
Operating Temperature - Junction	-65°C ~ 125°C
RoHS Status	RoHS non-compliant
Product Status	Discontinued at DiGi Electronics

Substitute Part Grouping Explanation

Substitution of the SK15-13 is determined by the following critical parameters:

Mandatory Compatibility Criteria:

Technology: Schottky (fast recovery rectifier diode)
Package / Case: DO-214AA, SMB (surface mount form factor)
Mounting Type: Surface Mount
Speed: Fast Recovery ≤ 500 ns, > 200 mA (Io)

Electrical Rating Considerations:

Voltage - DC Reverse (Vr) (Max): Substitute must equal or exceed 50 V
Current - Average Rectified (Io): Substitute must equal or exceed 1 A
Voltage - Forward (Vf) (Max) @ If: Lower values indicate improved efficiency
Current - Reverse Leakage @ Vr: Lower values indicate reduced standby current

Substitute parts are grouped into two categories based on voltage rating:

Category A - 50 V Rated (Direct Voltage Match):

SK35B-LTP: 50 V, 3 A (higher current rating, not for new designs)

Category B - 40 V Rated (Reduced Voltage Rating):

STPS140U: 40 V, 1 A (exact current match, active product)
STPS1L40U: 40 V, 1 A (exact current match, active product)
STPS1L40UY: 40 V, 1 A (automotive grade, active product)
STPS2L40U: 40 V, 2 A (higher current rating, active product)
STPS340U: 40 V, 3 A (higher current rating, active product)
STPS340UY: 40 V, 3 A (automotive grade, active product)

Category B substitutes operate at reduced maximum reverse voltage (40 V vs. 50 V) and are suitable only for applications where the actual operating voltage does not exceed 40 V.

Parameter Comparison

Part Number	Manufacturer	Vr (Max)	Io (A)	Vf (Max) @ If	Reverse Leakage @ Vr	Package	Product Status	RoHS Status
SK15-13	Diodes Incorporated	50 V	1 A	700 mV @ 1 A	500 µA @ 50 V	DO-214AA, SMB	Discontinued	Non-compliant
SK35B-LTP	Micro Commercial Co	50 V	3 A	750 mV @ 3 A	500 µA @ 50 V	DO-214AA, SMB	Not For New Designs	ROHS3 Compliant
STPS140U	STMicroelectronics	40 V	1 A	550 mV @ 1 A	12 µA @ 40 V	DO-214AA, SMB	Active	ROHS3 Compliant
STPS1L40U	STMicroelectronics	40 V	1 A	500 mV @ 1 A	35 µA @ 40 V	DO-214AA, SMB	Active	ROHS3 Compliant
STPS1L40UY	STMicroelectronics	40 V	1 A	500 mV @ 1 A	35 µA @ 40 V	DO-214AA, SMB	Active	ROHS3 Compliant
STPS2L40U	STMicroelectronics	40 V	2 A	430 mV @ 2 A	220 µA @ 40 V	DO-214AA, SMB	Active	ROHS3 Compliant
STPS340U	STMicroelectronics	40 V	3 A	630 mV @ 3 A	20 µA @ 40 V	DO-214AA, SMB	Active	ROHS3 Compliant
STPS340UY	STMicroelectronics	40 V	3 A	630 mV @ 3 A	20 µA @ 40 V	DO-214AA, SMB	Active	ROHS3 Compliant

Engineering Selection Recommendations

For 50 V Voltage Rating Requirement:

SK35B-LTP is the only substitute maintaining the 50 V reverse voltage specification. However, this part is classified as "Not For New Designs" and carries RoHS3 compliance. Selection of SK35B-LTP is appropriate only for legacy system maintenance or where 50 V rating is mandatory and the higher 3 A current rating does not create thermal or circuit design conflicts.

For Active Product Status with RoHS3 Compliance:

STMicroelectronics STPS series diodes (STPS140U, STPS1L40U, STPS1L40UY, STPS2L40U, STPS340U, STPS340UY) are all classified as Active products with ROHS3 compliance. These parts are suitable for new designs and ongoing production. Selection from this series requires verification that the application operating voltage does not exceed 40 V maximum reverse voltage.

For Automotive Applications:

STPS1L40UY and STPS340UY are qualified to AEC-Q101 automotive standards and carry automotive grade designation. These parts are appropriate for automotive and mission-critical applications requiring automotive-grade component qualification.

For Exact Current Rating Match (1 A):

STPS140U, STPS1L40U, and STPS1L40UY all provide 1 A average rectified current matching the SK15-13 specification. STPS1L40U and STPS1L40UY offer superior forward voltage characteristics (500 mV vs. 550 mV @ 1 A) compared to STPS140U.

For Improved Efficiency:

STPS1L40U and STPS1L40UY exhibit lower forward voltage drop (500 mV @ 1 A) compared to the original SK15-13 (700 mV @ 1 A), resulting in reduced power dissipation and improved circuit efficiency.

Frequently Asked Questions (FAQ)

Q: Can STPS140U, STPS1L40U, or STPS1L40UY be used as direct replacements for SK15-13?

A: These parts are compatible substitutes provided the application maximum reverse voltage does not exceed 40 V. All three maintain the 1 A current rating, surface mount SMB package, and fast recovery Schottky technology. The 40 V rating is lower than the original 50 V specification; circuit design must confirm that actual operating voltages remain within 40 V limits.

Q: What is the difference between STPS1L40U and STPS1L40UY?

A: Both parts share identical electrical specifications (40 V, 1 A, 500 mV forward voltage). STPS1L40UY carries automotive grade designation and AEC-Q101 qualification, with operating temperature range of -40°C to 150°C. STPS1L40U has a maximum operating temperature of 150°C without automotive qualification. Selection depends on application requirements for automotive-grade components.

Q: Why do some substitute parts have higher current ratings (2 A or 3 A)?

A: STPS2L40U and STPS340U/STPS340UY provide higher current capacity while maintaining the same 40 V voltage rating and SMB package. These parts are suitable for applications where the SK15-13 is used but higher current capacity is beneficial or required. The higher current rating does not prevent use in 1 A applications; the diode will operate within its rated limits.

Q: Is SK35B-LTP a suitable replacement for new designs?

A: SK35B-LTP maintains the 50 V voltage rating and is the only substitute with this specification. However, it is classified as "Not For New Designs" by the manufacturer. This part is appropriate only for legacy system support or maintenance where 50 V rating is mandatory and design continuity is required. For new designs, active STMicroelectronics STPS series parts are recommended.

Q: What is the impact of the 40 V rating on applications originally designed for 50 V?

A: Applications must be evaluated to confirm that actual operating reverse voltages do not exceed 40 V. If the circuit design includes transient overvoltage conditions or worst-case voltage scenarios that approach or exceed 40 V, the 40 V rated substitutes are not appropriate. In such cases, SK35B-LTP (50 V) is the only available substitute, despite its "Not For New Designs" status.

Q: How do forward voltage characteristics affect circuit performance?

A: Forward voltage drop directly impacts power dissipation and circuit efficiency. STPS1L40U and STPS1L40UY (500 mV @ 1 A) dissipate less power than SK15-13 (700 mV @ 1 A), resulting in lower junction temperature and improved thermal performance. STPS140U (550 mV @ 1 A) provides intermediate performance. Lower forward voltage is beneficial in power-sensitive applications.

Q: Are all substitute parts RoHS compliant?

A: All STMicroelectronics STPS series substitutes (STPS140U, STPS1L40U, STPS1L40UY, STPS2L40U, STPS340U, STPS340UY) are ROHS3 compliant. SK35B-LTP is also ROHS3 compliant. The original SK15-13 is RoHS non-compliant. Selection of RoHS3 compliant substitutes is required for applications subject to RoHS regulations.

Q: Can STPS2L40U or STPS340U be used in place of SK15-13 in a 1 A application?

A: Yes. STPS2L40U (2 A) and STPS340U (3 A) are electrically compatible with 1 A applications. The higher current rating indicates the diode can safely conduct higher currents; it will operate within specification at 1 A. These parts are suitable when higher current capacity provides design margin or when standardizing on a single part number across multiple circuit variants.

Q: What packaging considerations apply to these substitutes?

A: All substitute parts use the DO-214AA, SMB surface mount package, identical to SK15-13. No PCB layout or footprint modifications are required. Thermal management considerations may differ due to variations in forward voltage and reverse leakage characteristics; thermal analysis is recommended for high-power applications.

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