CS8321YT3 Linear Voltage Regulator - Equivalent & Substitute Parts

Part Overview

The CS8321YT3 is a linear voltage regulator IC manufactured by onsemi, designed to deliver a fixed 5V output at 150mA in a TO-220-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for new designs and production continuity. The CS8321YT3 provides basic voltage regulation with reverse polarity and short circuit protection, suitable for low-current applications requiring a positive fixed output voltage.

Key Parameters

Parameter	CS8321YT3 Value
Output Voltage (Fixed)	5V
Output Current	150mA
Input Voltage (Max)	45V
Voltage Dropout (Max)	0.5V @ 150mA
Package / Case	TO-220-3
Mounting Type	Through Hole
Operating Temperature Range	-40°C ~ 125°C
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the CS8321YT3 are selected based on the following criteria:

Fixed 5V output voltage matching the original specification
TO-220-3 package for mechanical and thermal compatibility
Output current rating equal to or greater than 150mA
Maximum input voltage of 26V or higher to accommodate the original 45V specification
Through-hole mounting type for direct PCB replacement
Operating temperature range of -40°C to 125°C or wider
Protection features including reverse polarity and short circuit protection

Substitute parts are grouped by output current capability, as this is the primary differentiator among active alternatives. All candidates maintain the fixed 5V output and TO-220-3 package form factor.

Parameter Comparison

Parameter	CS8321YT3	MIC2954-02WT	MIC2937A-5.0WT	LM2940T-5.0/LF08	L4940V5	MIC29150-5.0WT	MIC29300-5.0WT	TL750M05CKCSE3
Manufacturer	onsemi	Microchip	Microchip	Texas Instruments	STMicroelectronics	Microchip	Microchip	Texas Instruments
Output Voltage	5V	5V	5V	5V	5V	5V	5V	5V
Output Current	150mA	250mA	750mA	1A	1.5A	1.5A	3A	750mA
Input Voltage (Max)	45V	30V	26V	26V	17V	26V	26V	26V
Voltage Dropout (Max)	0.5V @ 150mA	0.6V @ 250mA	—	1V @ 1A	0.9V @ 1.5A	0.6V @ 1.5A	0.6V @ 3A	0.6V @ 750mA
Package / Case	TO-220-3	TO-220-3	TO-220-3	TO-220-3 Formed Leads	TO-220-3	TO-220-3	TO-220-3	TO-220-3
Mounting Type	Through Hole	Through Hole	Through Hole	Surface Mount	Through Hole	Through Hole	Through Hole	Through Hole
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 150°C	-40°C ~ 125°C	-40°C ~ 125°C	0°C ~ 125°C
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

All substitute parts listed are active products with ROHS3 compliance, providing long-term availability and regulatory alignment compared to the obsolete CS8321YT3.

For direct pin-compatible replacement in existing through-hole PCB designs, MIC2954-02WT offers the closest current rating at 250mA with identical TO-220-3 package and through-hole mounting. This part maintains the same thermal and mechanical footprint while providing enhanced protection features and active product status.

For applications requiring higher current capacity, MIC2937A-5.0WT and TL750M05CKCSE3 both deliver 750mA output current in TO-220-3 through-hole packages. MIC2937A-5.0WT provides superior dropout performance at the rated current, while TL750M05CKCSE3 offers additional over-voltage protection.

For maximum design margin and future scalability, MIC29150-5.0WT and L4940V5 provide 1.5A output current. MIC29150-5.0WT maintains the -40°C to 125°C temperature range and includes transient voltage protection. L4940V5 extends the operating range to 150°C, suitable for high-temperature environments.

LM2940T-5.0/LF08 is not recommended as a direct replacement due to surface-mount package configuration, which requires PCB redesign for through-hole applications.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with higher output current than the original CS8321YT3?

A: Yes. A regulator with higher current capacity is a valid substitute provided all other parameters remain compatible. Higher current rating does not affect circuit operation at lower current levels. The circuit will draw only the current it requires.

Q: What is the significance of the TO-220-3 package for substitution?

A: The TO-220-3 package defines the physical form factor and pin configuration. All substitute parts listed use this identical package, ensuring mechanical compatibility with existing PCB layouts and thermal management solutions without redesign.

Q: Why is the LM2940T-5.0/LF08 listed if it uses surface-mount packaging?

A: LM2940T-5.0/LF08 is included for reference as an electrically equivalent alternative. However, it requires PCB redesign due to its surface-mount package configuration and is not suitable for direct through-hole replacement.

Q: Does higher input voltage rating affect substitution compatibility?

A: No. A substitute part with a lower maximum input voltage (such as L4940V5 at 17V versus the original 45V) is still compatible if the actual input voltage in the application does not exceed the substitute's rating. Verify your circuit's input voltage before selection.

Q: Are all substitute parts RoHS compliant?

A: Yes. All active substitute parts listed are ROHS3 compliant, whereas the original CS8321YT3 is non-compliant. This compliance status is important for new designs and applications subject to environmental regulations.

Q: What protection features should I prioritize when selecting a substitute?

A: All substitute parts include reverse polarity and short circuit protection, matching the original CS8321YT3. Additional features such as over-temperature, over-current, and transient voltage protection are available in several alternatives and provide enhanced reliability for sensitive applications.

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