CDST-21C-G Equivalent & Substitute Parts

Part Overview

The CDST-21C-G is a general-purpose diode array manufactured by Comchip Technology, configured as a 1 Pair Common Cathode device in a surface mount SOT-23-3 package. This component operates at 250 V DC reverse voltage with 200 mA average rectified current per diode and is classified as obsolete. Due to its obsolete status, identifying equivalent and substitute parts is essential for design continuity, production support, and long-term component availability in applications requiring this diode array configuration.

Substiute Parts

CDST-21C-G

Comchip TechnologyIn Stock: 810CDST-21C-G Datasheet

Current PartRFQ

BAS21C-HF

Comchip TechnologyIn Stock: 4958BAS21C-HF Datasheet

DirectRFQ

BAS21C RFG

Taiwan Semiconductor CorporationIn Stock: 6989BAS21C RFG Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

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

Mandatory Matching Parameters:

• Diode Configuration: 1 Pair Common Cathode
• 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 (equal or higher ratings are acceptable)

Electrical Performance Parameters:

• Voltage - Forward (Vf) (Max) @ If: 1.25 V @ 200 mA or lower
• Reverse Recovery Time (trr): 50 ns or faster
• Current - Reverse Leakage @ Vr: Specified at 200 V

Substitute parts must meet or exceed all mandatory parameters. Parts with higher current ratings or improved leakage characteristics are acceptable as direct substitutes.

Parameter Comparison

Engineering Selection Recommendations

BAS21C-HF (Comchip Technology): This part is the direct manufacturer substitute from Comchip Technology. It maintains identical reverse voltage (250 V), forward voltage characteristics (1.25 V @ 200 mA), and reverse recovery time (50 ns). The BAS21C-HF offers doubled current capacity (400 mA vs. 200 mA) and improved reverse leakage performance (100 nA vs. 1 µA @ 200 V). Product status is Active with full availability. This substitute is suitable for direct replacement in applications where the original CDST-21C-G is specified, with the added benefit of higher current margin and lower leakage characteristics.

BAS21C RFG (Taiwan Semiconductor Corporation): This part is a parametric equivalent from an alternative manufacturer. It matches the CDST-21C-G in diode configuration, reverse voltage (250 V), current rating (200 mA), forward voltage (1.25 V @ 200 mA), and reverse recovery time (50 ns). The BAS21C RFG provides improved reverse leakage (100 nA vs. 1 µA @ 200 V) and extended operating temperature range (-55°C ~ 150°C vs. 150°C max). Product status is Active. This substitute is suitable for applications requiring parametric equivalence with an alternative manufacturer source.

Both substitutes are ROHS3 compliant, MSL Level 1, and maintain identical SOT-23-3 surface mount packaging, ensuring PCB compatibility without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can BAS21C-HF be used as a direct replacement for CDST-21C-G?

A: Yes. BAS21C-HF is a direct substitute from the same manufacturer (Comchip Technology) with identical reverse voltage (250 V), forward voltage characteristics (1.25 V @ 200 mA), and reverse recovery time (50 ns). The higher current rating (400 mA vs. 200 mA) and improved reverse leakage (100 nA vs. 1 µA) provide additional performance margin. Identical SOT-23-3 packaging ensures no PCB modifications are required.

Q: What is the difference between BAS21C-HF and BAS21C RFG?

A: BAS21C-HF is manufactured by Comchip Technology (same as the original part) with 400 mA current capacity. BAS21C RFG is manufactured by Taiwan Semiconductor Corporation with 200 mA current capacity matching the original specification. Both maintain identical reverse voltage (250 V), forward voltage (1.25 V @ 200 mA), and reverse recovery time (50 ns). BAS21C RFG offers extended operating temperature range (-55°C ~ 150°C). Selection depends on manufacturer preference and current margin requirements.

Q: Are the substitute parts pin-compatible with CDST-21C-G?

A: Yes. Both BAS21C-HF and BAS21C RFG use identical TO-236-3, SC-59, SOT-23-3 surface mount packaging with the same pin configuration (1 Pair Common Cathode). No PCB layout or schematic modifications are required for substitution.

Q: What is the significance of the improved reverse leakage in the substitute parts?

A: The substitute parts (BAS21C-HF and BAS21C RFG) specify reverse leakage of 100 nA @ 200 V compared to 1 µA @ 200 V for the original CDST-21C-G. Lower reverse leakage reduces standby current consumption and improves circuit performance in applications sensitive to leakage current, such as precision analog circuits or low-power designs.

Q: Are both substitute parts available in the same packaging options?

A: Both BAS21C-HF and BAS21C RFG are supplied in Tape & Reel (TR) packaging for surface mount assembly. The CDST-21C-G packaging format was not specified in the original documentation. Both substitutes are suitable for automated PCB assembly processes.

Q: Why is CDST-21C-G classified as obsolete?

A: The CDST-21C-G is marked as obsolete, indicating it is no longer in active production. The substitute parts BAS21C-HF and BAS21C RFG are both classified as Active products with current manufacturing and full availability, making them the recommended alternatives for new designs and ongoing production support.

Q: Can BAS21C-HF be used in applications requiring the exact 200 mA current specification?

A: Yes. Although BAS21C-HF is rated for 400 mA, it operates within the 200 mA specification of the original CDST-21C-G. The higher rating provides design margin and does not affect circuit operation at lower current levels. The forward voltage and reverse voltage characteristics remain identical at the 200 mA operating point.