CDST-21A-HF Equivalent & Substitute Parts

Part Overview

The CDST-21A-HF is a general-purpose diode array manufactured by Comchip Technology, configured as a 1 Pair Common Anode device rated for 250 V DC reverse voltage and 200 mA average rectified current per diode. The component is packaged in a Surface Mount TO-236-3 (SOT-23-3) configuration and is classified as obsolete product status.

Due to its obsolete classification, direct replacement with active production equivalents is necessary for new designs and ongoing procurement. Substitute parts maintain electrical and mechanical compatibility while offering improved availability and active manufacturer support.

Substiute Parts

CDST-21A-HF

Comchip TechnologyIn Stock: 1123CDST-21A-HF Datasheet

Current PartRFQ

BAS21A-HF

Comchip TechnologyIn Stock: 2713BAS21A-HF Datasheet

DirectRFQ

BAS21A RFG

Taiwan Semiconductor CorporationIn Stock: 7026BAS21A RFG Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the CDST-21A-HF are classified into two categories based on electrical parameter alignment:

Direct Manufacturer Substitute (Active Production): BAS21A-HF 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 primary difference is increased current rating (400 mA versus 200 mA), which provides enhanced current capacity while maintaining full backward compatibility. This part is manufactured by Comchip Technology and carries active product status.

Parametric Equivalent (Alternative Manufacturer): BAS21A RFG, manufactured by Taiwan Semiconductor Corporation, provides identical electrical specifications to the original CDST-21A-HF, including 250 V reverse voltage, 200 mA current rating, 1.25 V forward voltage, 50 ns reverse recovery time, and 100 nA reverse leakage. This part is classified as parametrically equivalent and carries active product status.

All substitute parts maintain the same diode configuration (1 Pair Common Anode), Surface Mount mounting type, SOT-23-3 package, ROHS3 compliance, and MSL 1 rating. Substitution is valid when the application circuit does not exceed the specified maximum ratings of the selected replacement part.

Parameter Comparison

Engineering Selection Recommendations

For New Designs and Active Procurement: BAS21A-HF is the primary substitute. This part is manufactured by the original equipment manufacturer (Comchip Technology), carries active product status, and provides increased current capacity (400 mA) over the original specification (200 mA). The enhanced current rating ensures margin in applications operating at or near the original 200 mA specification. ROHS3 compliance and unlimited MSL rating maintain environmental and handling compatibility with the original part.

For Parametric Equivalence Requirement: BAS21A RFG provides an alternative from Taiwan Semiconductor Corporation with identical electrical specifications to the original CDST-21A-HF. This part is suitable when current capacity increase is not required and parametric matching to the original part is the primary selection criterion. Active product status and ROHS3 compliance are maintained. The extended operating temperature range (−55°C to 150°C) provides additional thermal margin compared to the original specification.

Both substitute parts are available in active production with established supply chains. Selection between BAS21A-HF and BAS21A RFG depends on procurement source preference, supply chain strategy, and whether the increased current capacity of BAS21A-HF provides design benefit.

Frequently Asked Questions (FAQ)

Q: Can BAS21A-HF be used as a direct replacement for CDST-21A-HF in existing designs?

A: Yes. BAS21A-HF maintains all critical electrical parameters: 250 V reverse voltage, 1.25 V forward voltage at 200 mA, 50 ns reverse recovery time, and 100 nA reverse leakage current. The increased current rating (400 mA versus 200 mA) is a superset of the original specification and does not affect compatibility. Package, mounting type, and configuration remain identical.

Q: What is the difference between BAS21A-HF and BAS21A RFG?

A: BAS21A-HF is manufactured by Comchip Technology and rated for 400 mA current. BAS21A RFG is manufactured by Taiwan Semiconductor Corporation and rated for 200 mA current, matching the original CDST-21A-HF specification. Both parts share identical reverse voltage, forward voltage, recovery time, and leakage characteristics. Selection depends on current requirement and manufacturer preference.

Q: Are all substitute parts in the same package?

A: All parts use Surface Mount TO-236-3 (SOT-23-3) packaging. The supplier device package designation is SOT-23-3 for CDST-21A-HF and BAS21A-HF, and SOT-23 for BAS21A RFG. These designations refer to the same physical package and are interchangeable for PCB layout and assembly purposes.

Q: Do the substitute parts meet the same compliance standards as the original?

A: Yes. Both BAS21A-HF and BAS21A RFG are ROHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity rating, matching the original CDST-21A-HF specifications.

Q: Why is the CDST-21A-HF classified as obsolete?

A: Obsolete classification indicates the part is no longer in active production by the manufacturer. Substitute parts with active status provide continued availability and manufacturer support for equivalent or enhanced functionality.

Q: Can BAS21A RFG be used if the application requires 400 mA current?

A: No. BAS21A RFG is rated for 200 mA maximum average rectified current per diode. Applications requiring 400 mA current must use BAS21A-HF, which is rated for that current level.

Q: What is the operating temperature range for each part?

A: CDST-21A-HF and BAS21A-HF specify a maximum junction temperature of 150°C. BAS21A RFG specifies an operating temperature range of −55°C to 150°C, providing extended low-temperature operation capability.