KA317TU Linear Voltage Regulator IC Equivalent & Substitute Parts

Part Overview

The KA317TU is a linear voltage regulator IC manufactured by onsemi, classified as a positive adjustable output regulator with 1.5A output current capability in TO-220-3 packaging. This component is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The KA317TU serves applications requiring adjustable positive voltage regulation from 1.2V to 37V output range with input voltages up to 40V.

Key Parameters

Parameter	Value
Manufacturer Part Number	KA317TU
Manufacturer	onsemi
Category	Power Management (PMIC)
Package / Case	TO-220-3
Output Configuration	Positive
Output Type	Adjustable
Voltage - Input (Max)	40V
Voltage - Output (Min/Fixed)	1.2V
Voltage - Output (Max)	37V
Current - Output	1.5A
PSRR	75dB ~ 60dB (120Hz)
Protection Features	Over Temperature, Short Circuit
Operating Temperature	0°C ~ 125°C
Mounting Type	Through Hole
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the KA317TU is determined by the following critical parameters:

Primary Substitution Criteria:

Output Configuration: Positive
Output Type: Adjustable
Package / Case: TO-220-3
Voltage - Input (Max): 40V minimum
Voltage - Output (Min/Fixed): 1.2V or lower
Voltage - Output (Max): 37V or higher
Current - Output: 1.5A or higher
Mounting Type: Through Hole

Substitute parts are grouped into two categories:

Direct Substitutes (1.5A Output Current): Parts meeting all primary criteria with 1.5A or greater output current, identical input/output voltage ranges, and TO-220-3 packaging. These provide pin-for-pin and functional equivalence.

Similar Substitutes (500mA Output Current): onsemi LM317 variants with reduced output current (500mA) but identical voltage specifications and TO-220-3 packaging. These are suitable only for applications with current requirements not exceeding 500mA.

Parameter Comparison

Part Number	Manufacturer	Output Current	Voltage Input (Max)	Voltage Output (Min)	Voltage Output (Max)	Package	Product Status	Operating Temp
KA317TU	onsemi	1.5A	40V	1.2V	37V	TO-220-3	Obsolete	0°C ~ 125°C
LM317KCS	Texas Instruments	1.5A	40V	1.25V	37V	TO-220-3	Active	0°C ~ 125°C
LM317KCSE3	Texas Instruments	1.5A	40V	1.25V	37V	TO-220-3	Last Time Buy	0°C ~ 125°C
LM317KCT	Texas Instruments	1.5A	40V	1.25V	37V	TO-220-3	Obsolete	0°C ~ 125°C
LM317T	NTE Electronics, Inc	1.5A	37V	1.25V	37V	TO-220-3	Active	0°C ~ 125°C
LM317T-BP	Micro Commercial Co	1.5A	40V	1.25V	37V	TO-220-3	Active	0°C ~ 125°C
LM317AT/NOPB	Texas Instruments	1.5A	40V	1.25V	37V	TO-220-3	Active	-40°C ~ 125°C
LM317MABTG	onsemi	500mA	40V	1.2V	37V	TO-220-3	Active	-40°C ~ 125°C
LM317MBTG	onsemi	500mA	40V	1.2V	37V	TO-220-3	Active	-40°C ~ 125°C
LM317MTG	onsemi	500mA	40V	1.2V	37V	TO-220-3	Active	0°C ~ 125°C
LM338T/NOPB	Texas Instruments	5A	40V	1.24V	32V	TO-220-3	Active	0°C ~ 125°C

Engineering Selection Recommendations

Preferred Direct Substitutes (1.5A Output Current):

LM317AT/NOPB (Texas Instruments) is the primary recommended substitute. This part is currently in active production status with extended operating temperature range (-40°C to 125°C), providing superior thermal performance compared to the obsolete KA317TU. It maintains identical electrical specifications, TO-220-3 packaging, and 1.5A output current capability. ROHS3 compliance and established supply chain availability support long-term design continuity.

LM317KCS (Texas Instruments) provides an alternative direct substitute with active product status and identical 1.5A output current. This part meets all electrical and mechanical requirements of the KA317TU with the exception of operating temperature range (0°C to 125°C versus KA317TU's 0°C to 125°C), making it suitable for standard industrial applications.

LM317T-BP (Micro Commercial Co) offers active production status with 1.5A output current and full voltage specification compatibility. This variant is available in bulk packaging and supports applications requiring high-volume procurement.

Alternative Consideration (5A Output Current):

LM338T/NOPB (Texas Instruments) provides higher output current capability (5A) in identical TO-220-3 packaging. This part is suitable only for applications where the maximum output voltage requirement does not exceed 32V, as the KA317TU supports 37V maximum output while the LM338T/NOPB is limited to 32V maximum output.

Lower Current Alternatives (500mA Output Current):

onsemi LM317 variants (LM317MABTG, LM317MBTG, LM317MTG) are suitable only for applications with output current requirements not exceeding 500mA. These parts maintain identical voltage specifications and TO-220-3 packaging but are not recommended as primary substitutes for designs requiring the full 1.5A output capability of the KA317TU.

Frequently Asked Questions (FAQ)

Q: Can LM317AT/NOPB directly replace KA317TU without circuit modification?

A: Yes. LM317AT/NOPB is a direct pin-for-pin and functional equivalent. Both parts use identical TO-220-3 packaging with the same pin configuration (Input, Adjust, Output). No circuit modifications are required for substitution.

Q: What is the difference between LM317KCS and LM317AT/NOPB?

A: Both parts provide 1.5A output current and identical electrical specifications. The primary difference is operating temperature range: LM317AT/NOPB operates from -40°C to 125°C, while LM317KCS operates from 0°C to 125°C. LM317AT/NOPB is recommended for applications requiring extended low-temperature performance.

Q: Can I use LM317MBTG (500mA) instead of KA317TU (1.5A)?

A: LM317MBTG is suitable only if your application requires output current not exceeding 500mA. If your design requires the full 1.5A output capability, LM317MBTG will not provide adequate current and may cause thermal stress or circuit malfunction. Use direct 1.5A substitutes (LM317AT/NOPB, LM317KCS, or LM317T-BP) for full compatibility.

Q: What is the significance of "Last Time Buy" status for LM317KCSE3?

A: Last Time Buy status indicates that Texas Instruments will discontinue this part after a specified date. While currently available, LM317KCSE3 should not be selected for new designs. LM317AT/NOPB or LM317KCS are recommended for long-term production continuity.

Q: Is LM338T/NOPB (5A) a suitable substitute for KA317TU (1.5A)?

A: LM338T/NOPB is not recommended as a direct substitute. While it provides higher output current (5A) and identical TO-220-3 packaging, the maximum output voltage is limited to 32V compared to KA317TU's 37V maximum output. Use this part only if your application does not require output voltages above 32V.

Q: What packaging options are available for LM317 substitutes?

A: All recommended direct substitutes are available in TO-220-3 through-hole packaging, matching the KA317TU package type. Tube and bulk packaging options are available depending on manufacturer and distributor. Verify packaging availability with your component supplier before finalizing procurement.

Q: Are all substitute parts ROHS3 compliant?

A: Most active production substitutes (LM317AT/NOPB, LM317KCS, LM317T-BP, and onsemi LM317 variants) are ROHS3 compliant. Verify compliance documentation with your supplier, particularly for legacy or last-time-buy parts.

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