CDST-21A-G Equivalent & Substitute Parts Reference

Part Overview

The CDST-21A-G is a general-purpose diode array manufactured by Comchip Technology, configured as a 1 Pair Common Anode device in SOT-23-3 surface mount packaging. This component is rated for 250 V DC reverse voltage with 200 mA average rectified current per diode. The product is currently classified as obsolete, necessitating identification of active equivalent and substitute components for ongoing design requirements and procurement continuity.

Substiute Parts

CDST-21A-G

Comchip TechnologyIn Stock: 894CDST-21A-G 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

Substitution eligibility for the CDST-21A-G is determined by the following critical parameters:

Mandatory Matching Parameters:

• Diode Configuration: 1 Pair Common Anode
• 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 Consideration:

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

Substitute parts are classified into two categories:

Direct Manufacturer Substitute (Comchip Technology BAS21A-HF): Identical manufacturer, same package, same reverse voltage rating, with enhanced current rating (400 mA) and improved reverse leakage characteristics. Maintains identical forward voltage specification and reverse recovery time.

Parametric Equivalent (Taiwan Semiconductor Corporation BAS21A RFG): Alternative manufacturer with identical electrical specifications matching the CDST-21A-G baseline parameters, including current rating, voltage ratings, and thermal characteristics. Provides active product status with equivalent compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Same Manufacturer Continuity): The BAS21A-HF from Comchip Technology is the direct manufacturer substitute. This component maintains identical package geometry, reverse voltage rating, and forward voltage characteristics. The enhanced current rating (400 mA versus 200 mA) provides design margin without requiring circuit modification. Reverse leakage current is improved by one order of magnitude (100 nA versus 1 µA), indicating superior device quality. Product status is active with full ROHS3 compliance and unlimited moisture sensitivity rating. This substitute is suitable for direct PCB assembly replacement without design changes.

For Alternative Sourcing (Multi-Vendor Strategy): The BAS21A RFG from Taiwan Semiconductor Corporation provides parametric equivalence with identical electrical specifications to the CDST-21A-G baseline. This component matches the original 200 mA current rating and all voltage specifications. Operating temperature range extends to -55°C, providing broader thermal coverage. Product status is active with equivalent ROHS3 compliance and REACH unaffected designation. This substitute supports supply chain diversification and long-term availability assurance.

Compliance Verification: Both substitute parts maintain ROHS3 compliance, EAR99 export classification, and identical HTSUS commodity codes (8541.10.0070) as the original component. No regulatory or compliance barriers exist for substitution.

Frequently Asked Questions (FAQ)

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

A: Yes. Both components share identical package designation (TO-236-3, SC-59, SOT-23-3), diode configuration (1 Pair Common Anode), reverse voltage rating (250 V), and forward voltage specification (1.25 V @ 200 mA). PCB footprints and circuit connections are compatible without modification.

Q: What is the advantage of BAS21A-HF over the original CDST-21A-G?

A: BAS21A-HF provides doubled current capacity (400 mA versus 200 mA per diode) and improved reverse leakage characteristics (100 nA versus 1 µA @ 200 V). The component is manufactured by the same vendor and maintains active product status, ensuring long-term availability.

Q: Is BAS21A RFG from Taiwan Semiconductor Corporation electrically identical to CDST-21A-G?

A: BAS21A RFG matches all critical electrical parameters of CDST-21A-G: 250 V reverse voltage, 200 mA average rectified current, 1.25 V forward voltage @ 200 mA, and 50 ns reverse recovery time. Operating temperature range is extended (-55°C to 150°C). Package and mounting specifications are identical.

Q: Are there any thermal performance differences between the substitute parts?

A: CDST-21A-G and BAS21A-HF both specify maximum junction temperature of 150°C. BAS21A RFG specifies an operating temperature range of -55°C to 150°C, providing extended low-temperature capability. All three components are rated for the same maximum junction temperature.

Q: Do the substitute parts require different PCB layout considerations?

A: No. All three components use identical SOT-23-3 surface mount packaging. PCB footprints, trace routing, and assembly processes remain unchanged. No layout modifications are necessary.

Q: What is the reverse leakage current difference, and does it affect circuit performance?

A: CDST-21A-G specifies 1 µA @ 200 V reverse leakage. Both BAS21A-HF and BAS21A RFG specify 100 nA @ 200 V, representing a 10-fold improvement. For most applications, this difference is negligible; however, high-impedance circuits benefit from the lower leakage specification.

Q: Are both substitute parts RoHS compliant?

A: Yes. BAS21A-HF and BAS21A RFG are both ROHS3 compliant with Moisture Sensitivity Level 1 (unlimited). No environmental or regulatory restrictions apply to substitution.

Q: Which substitute should be selected for new designs?

A: For new designs requiring the 200 mA specification, BAS21A RFG provides multi-vendor sourcing flexibility with active product status. For designs benefiting from increased current capacity, BAS21A-HF offers enhanced performance from the original manufacturer with doubled current rating.