NCP431ACLPRAG Equivalent & Substitute Parts

Part Overview

The NCP431ACLPRAG is an adjustable shunt voltage reference IC manufactured by onsemi, designed for precision voltage regulation applications. This device features a 2.5V to 36V adjustable output with ±1% tolerance and is housed in a TO-92 package. The part is currently classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. Substitute parts maintain the core shunt reference functionality while offering improved availability and extended operating temperature ranges.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Adjustable
Voltage - Output (Min/Fixed)	2.5V
Voltage - Output (Max)	36V
Current - Output	40 µA
Tolerance	±1%
Temperature Coefficient	50ppm/°C Typical
Current - Cathode	100 mA
Operating Temperature	0°C ~ 70°C
Package / Case	TO-226-3, TO-92-3 Long Body
Mounting Type	Through Hole
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the NCP431ACLPRAG is determined by the following critical parameters:

Reference Type: Shunt (all substitutes maintain this topology)
Output Type: Adjustable (voltage reference must be adjustable)
Voltage Range: 2.5V minimum to 36V maximum output capability
Tolerance: ±1% or better (±0.5% substitutes are acceptable as tighter tolerance)
Package: TO-92-3 or TO-226-3 (through-hole compatibility required)
Current Output: Minimum 40 µA (substitutes provide 100 mA, exceeding requirement)
Temperature Coefficient: 50ppm/°C or better

Substitute parts are categorized as:

Upgrade Parts: Direct replacements with improved specifications (higher current output, extended temperature range, active product status)

Similar Parts: Functionally equivalent with minor specification variations (different tolerance grades, alternative manufacturers)

Parameter Comparison

Part Number	Manufacturer	Output (Min)	Output (Max)	Current Output	Tolerance	Temp Coeff	Operating Temp	Cathode Current	Status
NCP431ACLPRAG	onsemi	2.5V	36V	40 µA	±1%	50ppm/°C	0°C ~ 70°C	100 mA	Obsolete
KA431AZTA	onsemi	2.495V	36V	100 mA	±1%	50ppm/°C	-25°C ~ 85°C	1 mA	Active
LM431BCZX	onsemi	2.495V	36V	100 mA	±1%	50ppm/°C	-25°C ~ 85°C	1 mA	Active
LM431BIZX	onsemi	2.495V	36V	100 mA	±1%	50ppm/°C	-40°C ~ 85°C	1 mA	Active
KA431LZTA	onsemi	2.495V	36V	100 mA	±0.5%	50ppm/°C	-25°C ~ 85°C	1 mA	Active
LM431ACZX	Fairchild Semiconductor	2.5V	36V	100 mA	±2%	50ppm/°C	-25°C ~ 85°C	1 mA	Active
TL431AIZ-AP	STMicroelectronics	2.495V	36V	100 mA	±1%	—	-40°C ~ 105°C	700 µA	Active
TL431AIZT	STMicroelectronics	2.495V	36V	100 mA	±1%	—	-40°C ~ 105°C	700 µA	Active
AS431AZTR-E1	Diodes Incorporated	2.5V	36V	100 mA	±0.5%	20ppm/°C	-40°C ~ 125°C	1 mA	Active
AS431AZTR-G1	Diodes Incorporated	2.5V	36V	100 mA	±0.5%	20ppm/°C	-40°C ~ 125°C	1 mA	Active
AS431BZTR-G1	Diodes Incorporated	2.5V	36V	100 mA	±1%	20ppm/°C	-40°C ~ 125°C	1 mA	Active

Engineering Selection Recommendations

Primary Upgrade Substitutes (Recommended for New Designs)

KA431AZTA, LM431BCZX, and LM431BIZX from onsemi provide direct functional equivalence with improved current output (100 mA vs. 40 µA) and extended operating temperature ranges. All three maintain onsemi manufacturing continuity and ROHS3 compliance. LM431BIZX offers the widest temperature range (-40°C ~ 85°C), suitable for industrial applications.

Cross-Manufacturer Alternatives

TL431AIZ-AP and TL431AIZT from STMicroelectronics are active products with extended temperature operation (-40°C ~ 105°C) and maintain ±1% tolerance. These parts are suitable for applications requiring higher temperature performance.

AS431AZTR-E1, AS431AZTR-G1, and AS431BZTR-G1 from Diodes Incorporated offer superior temperature coefficient (20ppm/°C vs. 50ppm/°C) and the widest operating temperature range (-40°C ~ 125°C). AS431AZTR variants provide ±0.5% tolerance for precision applications.

Tolerance Considerations

KA431LZTA and AS431AZTR variants offer ±0.5% tolerance, providing tighter voltage regulation than the original ±1% specification. LM431ACZX features ±2% tolerance and should be selected only when tolerance relaxation is acceptable.

All substitute parts maintain ROHS3 compliance and are classified as active products, ensuring long-term availability and supply chain stability.

Frequently Asked Questions (FAQ)

Q: Can I directly replace NCP431ACLPRAG with KA431AZTA without circuit modifications?

A: Yes. Both parts are adjustable shunt voltage references with identical output voltage range (2.5V to 36V), ±1% tolerance, and TO-92-3 package compatibility. The KA431AZTA provides higher output current (100 mA vs. 40 µA), which is a functional improvement. No circuit changes are required.

Q: What is the difference between onsemi KA431 and LM431 series?

A: Both are onsemi products with identical electrical specifications (2.495V output, 36V maximum, ±1% tolerance, 50ppm/°C temperature coefficient). The primary difference is operating temperature range: KA431AZTA operates -25°C ~ 85°C, while LM431BIZX extends to -40°C ~ 85°C. Select based on application temperature requirements.

Q: Are Diodes Incorporated AS431 parts compatible with the original NCP431ACLPRAG?

A: Yes. AS431 parts maintain the same adjustable shunt reference topology, 2.5V to 36V output range, and TO-92-3 package. AS431 variants offer superior temperature coefficient (20ppm/°C) and extended operating range (-40°C ~ 125°C). Tolerance varies by grade: AS431AZTR provides ±0.5%, AS431BZTR provides ±1%.

Q: Why do substitute parts show different cathode current specifications?

A: Cathode current (minimum operating current) varies by manufacturer design. The original NCP431ACLPRAG specifies 100 mA cathode current. Substitutes range from 700 µA to 1 mA. This parameter affects minimum load requirements but does not impact voltage reference accuracy or output voltage range. Verify your circuit's minimum load current against the selected substitute's cathode current specification.

Q: Can I use TL431 parts from STMicroelectronics as a substitute?

A: Yes. TL431AIZ-AP and TL431AIZT maintain ±1% tolerance and 2.495V to 36V output range. These parts offer extended temperature operation (-40°C ~ 105°C) and are suitable for industrial and automotive applications. Cathode current is 700 µA, which may require circuit adjustment if your design relies on higher minimum load current.

Q: What is the advantage of selecting ±0.5% tolerance substitutes over ±1%?

A: ±0.5% tolerance parts (KA431LZTA, AS431AZTR-E1, AS431AZTR-G1) provide tighter voltage regulation, reducing output voltage variation across the tolerance band. Select these for precision voltage reference applications where tighter regulation improves system performance. Standard ±1% parts are sufficient for general-purpose voltage regulation.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts are ROHS3 compliant. The original NCP431ACLPRAG is also ROHS3 compliant. All parts are REACH unaffected and classified under ECCN EAR99.

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