CMSH3-20M BK PBFREE Schottky Diode Equivalent & Substitute Parts

Part Overview

The CMSH3-20M BK PBFREE is a 20V, 3A Schottky rectifier diode manufactured by Central Semiconductor Corp in Surface Mount SMB (DO-214AA) package. This component is classified as Active product status and is RoHS3 compliant with unlimited moisture sensitivity level (MSL 1).

Schottky diodes in this voltage and current class are widely used in power supply circuits, DC-DC converters, and reverse polarity protection applications. Substitute parts become necessary due to component availability, supply chain constraints, or design optimization requirements while maintaining electrical and mechanical compatibility.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) Maximum	20	V
Current - Average Rectified (Io)	3	A
Voltage - Forward (Vf) Maximum @ If	550 mV @ 3 A	mV
Speed - Fast Recovery	≤ 500ns, > 200mA (Io)	ns
Current - Reverse Leakage @ Vr	500	µA @ 20V
Capacitance @ Vr, F	139	pF @ 4V, 1MHz
Package / Case	DO-214AA, SMB	—
Operating Temperature - Junction	-65 to 150	°C
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the CMSH3-20M BK PBFREE is determined by the following critical parameters:

Primary Compatibility Criteria:

Voltage - DC Reverse (Vr) Maximum: Must equal or exceed 20V
Package / Case: Must be DO-214AA (SMB) or compatible surface mount package
Technology: Schottky rectifier diode
RoHS Status: ROHS3 Compliant
Mounting Type: Surface Mount

Secondary Compatibility Criteria:

Current - Average Rectified (Io): 2A or 3A ratings are acceptable
Operating Temperature Range: Must support -55°C to 150°C minimum
Speed: Fast Recovery ≤ 500ns, > 200mA (Io)
Reverse Leakage: 400-500 µA @ 20V acceptable

Substitute parts are grouped into two categories:

Group 1 - Direct Current Rating Match (3A): SK32B-TP maintains identical 3A current rating with matching voltage and package specifications. This part is Obsolete but electrically equivalent.

Group 2 - Reduced Current Rating (2A): B220-13-F, B220A-13-F, B220Q-13-F, SL22-E3/52T, SS22-E3/52T, and SS22-E3/5BT operate at 2A average rectified current. These parts are suitable for applications where the 3A rating of the main part exceeds circuit requirements, provided thermal and current handling margins remain adequate.

Parameter Comparison

Parameter	CMSH3-20M BK PBFREE	B220-13-F	B220A-13-F	B220Q-13-F	SK32B-TP	SL22-E3/52T	SS22-E3/52T	SS22-E3/5BT
Manufacturer	Central Semiconductor	Diodes Inc.	Diodes Inc.	Diodes Inc.	Micro Commercial Co	Vishay	Vishay	Vishay
Vr (Max)	20V	20V	20V	20V	20V	20V	20V	20V
Io (Avg Rectified)	3A	2A	2A	2A	3A	2A	2A	2A
Vf (Max) @ If	550 mV @ 3A	500 mV @ 2A	500 mV @ 2A	500 mV @ 2A	500 mV @ 3A	440 mV @ 2A	500 mV @ 2A	500 mV @ 2A
Speed (Fast Recovery)	≤ 500ns	≤ 500ns	≤ 500ns	≤ 500ns	≤ 500ns	≤ 500ns	≤ 500ns	≤ 500ns
Reverse Leakage @ Vr	500 µA @ 20V	500 µA @ 20V	500 µA @ 20V	500 µA @ 20V	500 µA @ 20V	400 µA @ 20V	400 µA @ 20V	400 µA @ 20V
Package	DO-214AA (SMB)	DO-214AA (SMB)	DO-214AC (SMA)	DO-214AA (SMB)	DO-214AA (SMB)	DO-214AA (SMB)	DO-214AA (SMB)	DO-214AA (SMB)
Tj Operating Range	-65 to 150°C	-65 to 150°C	-65 to 150°C	-65 to 150°C	-55 to 125°C	-55 to 125°C	-65 to 125°C	-65 to 125°C
Product Status	Active	Active	Active	Active	Obsolete	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

For Direct Replacement (3A Current Rating):

SK32B-TP from Micro Commercial Co provides electrical equivalence with identical 3A average rectified current and 20V reverse voltage rating in DO-214AA package. However, this part carries Obsolete product status, indicating discontinued manufacturing. Selection of SK32B-TP is appropriate only when existing inventory is available and long-term supply is not a requirement. The operating temperature range (-55 to 125°C) is narrower than the main part, which may impact applications requiring extended low-temperature operation below -55°C.

For Reduced Current Applications (2A Rating):

B220-13-F, B220Q-13-F, SL22-E3/52T, SS22-E3/52T, and SS22-E3/5BT are all Active products suitable for circuits where average rectified current does not exceed 2A. All maintain 20V reverse voltage rating, fast recovery characteristics, and RoHS3 compliance.

B220-13-F (Diodes Inc., Cut Tape & Digi-Reel): Highest inventory availability (65,310 pcs). Operating temperature range matches main part (-65 to 150°C). Forward voltage 500 mV @ 2A.
B220Q-13-F (Diodes Inc., Tape & Reel): Automotive-qualified per AEC-Q101 with lower inventory (3,868 pcs). Identical electrical specifications to B220-13-F. Selection appropriate for automotive or mission-critical applications requiring qualification documentation.
SL22-E3/52T (Vishay, Tape & Reel): Lower forward voltage (440 mV @ 2A) reduces power dissipation. Operating temperature range -55 to 125°C. Inventory 10,200 pcs.
SS22-E3/52T (Vishay, Cut Tape): Operating temperature -65 to 125°C. Forward voltage 500 mV @ 2A. Inventory 28,650 pcs.
SS22-E3/5BT (Vishay, Cut Tape & Digi-Reel): Highest inventory among 2A options (47,700 pcs). Operating temperature -65 to 125°C. Forward voltage 500 mV @ 2A.

Package Consideration:

B220A-13-F uses DO-214AC (SMA) package instead of DO-214AA (SMB). This part is not recommended as a direct substitute due to different footprint and PCB layout requirements, despite matching electrical specifications.

Compliance and Regulatory:

All substitute parts maintain ROHS3 compliance and MSL 1 (Unlimited) rating, ensuring compatibility with modern manufacturing processes and storage requirements.

Frequently Asked Questions (FAQ)

Q1: Can I use a 2A-rated substitute part in place of the 3A CMSH3-20M BK PBFREE?

A: Yes, provided your circuit design does not require the full 3A average rectified current capacity. The 2A-rated substitutes (B220-13-F, B220Q-13-F, SL22-E3/52T, SS22-E3/52T, SS22-E3/5BT) maintain identical 20V reverse voltage rating and fast recovery characteristics. Verify that your application's maximum forward current does not exceed 2A during normal operation and transient conditions.

Q2: What is the difference between B220-13-F and B220Q-13-F?

A: Both parts are manufactured by Diodes Inc. with identical electrical specifications (20V, 2A, DO-214AA package). The primary difference is that B220Q-13-F carries AEC-Q101 automotive qualification and is supplied in Tape & Reel packaging, while B220-13-F is supplied in Cut Tape & Digi-Reel format. Select B220Q-13-F for automotive applications requiring qualification documentation.

Q3: Why is SK32B-TP listed as a substitute if it is Obsolete?

A: SK32B-TP provides the closest electrical match with 3A average rectified current rating identical to the main part. It is included for reference in applications where existing inventory is available. For new designs or long-term production, select from Active-status alternatives such as B220-13-F or SS22-E3/5BT.

Q4: Can I use B220A-13-F as a substitute?

A: B220A-13-F has identical electrical specifications but uses DO-214AC (SMA) package instead of DO-214AA (SMB). Direct substitution is not recommended without PCB layout modification, as the footprints are different. If your PCB is designed for SMA package, B220A-13-F is electrically compatible.

Q5: What is the significance of forward voltage (Vf) differences between substitute parts?

A: Forward voltage affects power dissipation in the diode. SL22-E3/52T has lower forward voltage (440 mV @ 2A) compared to other 2A options (500 mV @ 2A), resulting in reduced heat generation. This may be advantageous in thermally constrained applications. The main part CMSH3-20M has 550 mV @ 3A, which is higher due to its higher current rating.

Q6: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts carry ROHS3 Compliant status and MSL 1 (Unlimited) rating, ensuring compatibility with lead-free soldering processes and unrestricted storage conditions.

Q7: What is the difference between Cut Tape, Tape & Reel, and Bulk packaging?

A: Packaging format affects supply and handling. Cut Tape (CT) and Digi-Reel are suitable for lower-volume production and prototyping. Tape & Reel (TR) is optimized for high-volume automated assembly. Bulk packaging is used for component distribution. Electrical specifications remain identical across packaging formats for the same part number.

Q8: Which substitute part has the best availability?

A: SS22-E3/5BT from Vishay has the highest inventory (47,700 pcs), followed by SS22-E3/52T (28,650 pcs) and B220-13-F (65,310 pcs). For immediate availability, B220-13-F is recommended despite lower total inventory, as it is supplied in multiple packaging formats.

Q9: Can I use a substitute part with a narrower operating temperature range?

A: Substitutes with narrower operating temperature ranges (such as SK32B-TP at -55 to 125°C versus main part at -65 to 150°C) are acceptable only if your application does not require operation below -55°C or above 125°C. Verify your circuit's thermal requirements before selection.

Q10: What does "Fast Recovery ≤ 500ns, > 200mA (Io)" mean?

A: This specification indicates that the diode's reverse recovery time is 500 nanoseconds or less when switching from forward to reverse bias at currents exceeding 200mA. All listed substitute parts meet this specification, ensuring compatibility in high-frequency switching applications such as DC-DC converters and power supplies.

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