CDST-21S-HF Equivalent & Substitute Parts

Part Overview

The CDST-21S-HF is a general-purpose diode array manufactured by Comchip Technology, configured as a 1 Pair Series Connection rated for 250 V DC reverse voltage and 200 mA average rectified current per diode. The device is packaged in SOT-23-3 surface mount configuration and is classified as obsolete product status. Due to its obsolete classification, equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for production and repair applications.

Substiute Parts

CDST-21S-HF

Comchip TechnologyIn Stock: 1209CDST-21S-HF Datasheet

Current PartRFQ

BAS21S-HF

Comchip TechnologyIn Stock: 8984BAS21S-HF Datasheet

DirectRFQ

BAS21S RFG

Taiwan Semiconductor CorporationIn Stock: 6684BAS21S RFG Datasheet

Parametric EquivalentRFQ

BAV23S

Good-Ark SemiconductorIn Stock: 305194BAV23S Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the CDST-21S-HF is determined by the following critical parameters that must be maintained or exceeded:

Mandatory Matching Parameters:

• Diode Configuration: 1 Pair Series Connection
• Voltage - DC Reverse (Vr) (Max): 250 V minimum
• Package / Case: TO-236-3, SC-59, SOT-23-3
• Mounting Type: Surface Mount
• RoHS Status: ROHS3 Compliant

Current Rating Compatibility:

• Current - Average Rectified (Io) (per Diode): 200 mA minimum

Electrical Performance Parameters:

• Voltage - Forward (Vf) (Max) @ If: 1.25 V @ 200 mA
• Reverse Recovery Time (trr): 50 ns
• Current - Reverse Leakage @ Vr: 100 nA @ 200 V

Substitute parts must satisfy all mandatory matching parameters. Variations in current rating, speed classification, and operating temperature range are permitted provided the specified electrical characteristics are maintained or improved.

Parameter Comparison

Engineering Selection Recommendations

BAS21S-HF (Comchip Technology)

The BAS21S-HF is a direct manufacturer equivalent from Comchip Technology with active product status. This part maintains identical reverse voltage (250 V), forward voltage characteristics (1.25 V @ 200 mA), reverse recovery time (50 ns), and reverse leakage current (100 nA @ 200 V). The BAS21S-HF provides enhanced current capability at 400 mA per diode, exceeding the CDST-21S-HF specification of 200 mA. This higher current rating provides design margin without compromising electrical performance. The part is ROHS3 compliant with MSL 1 rating and is available in high inventory quantities (8941 pcs).

BAS21S RFG (Taiwan Semiconductor Corporation)

The BAS21S RFG is a parametric equivalent manufactured by Taiwan Semiconductor Corporation with active product status. This part matches the CDST-21S-HF across all critical electrical parameters: 250 V reverse voltage, 200 mA current rating, 1.25 V forward voltage @ 200 mA, 50 ns reverse recovery time, and 100 nA reverse leakage @ 200 V. The BAS21S RFG provides an extended operating temperature range (-55°C to 150°C) compared to the CDST-21S-HF specification. The part is ROHS3 compliant with MSL 1 rating and is available in high inventory quantities (6655 pcs).

BAV23S (Good-Ark Semiconductor)

The BAV23S is a parametric equivalent manufactured by Good-Ark Semiconductor with active product status. This part maintains the 250 V reverse voltage and identical forward voltage characteristics (1.25 V @ 200 mA). The BAV23S current rating is 225 mA per diode, which exceeds the CDST-21S-HF specification of 200 mA. Reverse recovery time (50 ns) and reverse leakage current (100 nA @ 250 V) meet or exceed the original specification. The BAV23S provides an extended operating temperature range (-55°C to 150°C). The part is ROHS3 compliant with MSL 1 rating and is available in the highest inventory quantity (305100 pcs).

All three substitute parts are ROHS3 compliant, possess MSL 1 moisture sensitivity ratings, and are packaged in identical SOT-23-3 surface mount configuration. Selection among these equivalents should be based on current requirement, temperature range requirements, and supply chain availability.

Frequently Asked Questions (FAQ)

Q: Can the BAS21S-HF replace the CDST-21S-HF in all applications?

A: The BAS21S-HF is a direct manufacturer equivalent with identical electrical characteristics at the specified operating point (1.25 V @ 200 mA, 50 ns reverse recovery time, 100 nA reverse leakage @ 200 V). The BAS21S-HF provides higher current capability (400 mA vs. 200 mA), which is compatible with designs rated for 200 mA operation. Both parts share identical package configuration (SOT-23-3) and mounting type (surface mount), enabling direct substitution at the component level.

Q: What is the difference between BAS21S RFG and BAV23S?

A: Both BAS21S RFG and BAV23S are parametric equivalents with active product status. The BAS21S RFG matches the CDST-21S-HF current rating at 200 mA, while the BAV23S provides 225 mA current capability. Both parts maintain identical reverse voltage (250 V), forward voltage (1.25 V @ 200 mA), and reverse recovery time (50 ns). The BAV23S specifies reverse leakage current at 250 V versus 200 V for the BAS21S RFG. Both parts offer extended operating temperature range (-55°C to 150°C) and are available in high inventory quantities.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. The CDST-21S-HF and all three substitute parts (BAS21S-HF, BAS21S RFG, BAV23S) are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity level rating.

Q: Can these parts be used interchangeably in PCB assembly?

A: Yes. All substitute parts are packaged in identical TO-236-3, SC-59, SOT-23-3 surface mount configuration with the same pin assignment for 1 Pair Series Connection diode array topology. PCB footprints and assembly processes require no modification.

Q: Which substitute part should be selected for new designs?

A: For new designs, either BAS21S-HF, BAS21S RFG, or BAV23S are appropriate selections based on current requirement and supply chain considerations. All three parts have active product status and high inventory availability. The BAS21S-HF and BAV23S provide enhanced current capability (400 mA and 225 mA respectively) compared to the original 200 mA specification, offering design margin. The BAS21S RFG provides exact current matching at 200 mA.

Q: What is the significance of the reverse recovery time (trr) specification?

A: Reverse recovery time (50 ns) is maintained across all substitute parts and the original CDST-21S-HF. This parameter determines the speed classification of the diode array and affects switching performance in high-frequency applications. The 50 ns specification is consistent across all parts, ensuring equivalent performance in applications sensitive to switching transients.

Q: Are there any temperature range considerations for substitution?

A: The CDST-21S-HF specifies maximum junction temperature of 150°C without a minimum operating temperature specification. The BAS21S-HF maintains the same 150°C maximum. The BAS21S RFG and BAV23S provide extended operating temperature range (-55°C to 150°C), which is compatible with the original specification and provides additional margin for low-temperature applications.