LM431CIM3X Equivalent & Substitute Parts

Part Overview

The LM431CIM3X is a shunt voltage reference IC manufactured by Texas Instruments, classified as a Power Management (PMIC) component. This adjustable reference device operates with a 2.5V output and supports up to 37V maximum, delivering 100 mA output current in a SOT-23-3 surface mount package. The LM431CIM3X is designated as Last Time Buy, indicating discontinued production status. Alternative equivalent and substitute parts are necessary to ensure design continuity and long-term component availability for new production runs and legacy system support.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Adjustable
Voltage - Output (Min/Fixed)	2.5V
Voltage - Output (Max)	37V
Current - Output	100 mA
Tolerance	-0.6%, +0.4%
Temperature Coefficient	50ppm/°C Typical
Current - Cathode	1 mA
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	TO-236-3, SC-59, SOT-23-3
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the LM431CIM3X is determined by strict electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Reference Type: Shunt (all substitutes must maintain shunt topology)
Output Type: Adjustable (functional equivalence required)
Voltage - Output (Min/Fixed): 2.5V nominal (±0.5% tolerance acceptable)
Voltage - Output (Max): 36V–37V range (maximum voltage rating must not be lower than 36V)
Current - Output: 100 mA (exact match required)
Package / Case: SOT-23-3 (mechanical and pinout compatibility)

Mechanical Compatibility Criteria:

Mounting Type: Surface Mount (identical)
Supplier Device Package: SOT-23-3 (identical)

Regulatory & Environmental Criteria:

RoHS Status: ROHS3 Compliant (all substitutes must meet or exceed)
Moisture Sensitivity Level (MSL): 1–3 acceptable (MSL 1 preferred for unlimited shelf life)

Substitute parts are categorized as follows:

Upgrade Substitutes (TL431 Series): Texas Instruments TL431BQDBZR, TL431BQDBZRQ1, and TL431BQDBZT offer improved tolerance (±0.5% vs. -0.6%, +0.4%), extended operating temperature range (-40°C ~ 125°C vs. -40°C ~ 85°C), and Active product status. These parts are direct functional upgrades with identical electrical performance and package compatibility.

Parametric Equivalents (LM431 Series): LM431CIM3, LM431CIM3/NOPB, and LM431CIM3X/NOPB maintain identical electrical specifications and tolerance characteristics. These parts provide exact parametric matching with the main part number.

Manufacturer Recommended Substitute (Diodes Incorporated AS431HMANTR-G1): The AS431HMANTR-G1 provides equivalent electrical performance with improved temperature coefficient (20ppm/°C vs. 50ppm/°C) and lower cathode current (500µA vs. 1mA), offering superior performance characteristics while maintaining SOT-23-3 package compatibility.

Parameter Comparison

Part Number	Manufacturer	Voltage Output (Min)	Voltage Output (Max)	Tolerance	Temp Coefficient	Cathode Current	Operating Temp	Product Status	Package
LM431CIM3X	Texas Instruments	2.5V	37V	-0.6%, +0.4%	50ppm/°C	1 mA	-40°C ~ 85°C	Last Time Buy	SOT-23-3
TL431BQDBZR	Texas Instruments	2.495V	36V	±0.5%	—	700µA	-40°C ~ 125°C	Active	SOT-23-3
TL431BQDBZRQ1	Texas Instruments	2.495V	36V	±0.5%	—	700µA	-40°C ~ 125°C	Active	SOT-23-3
TL431BQDBZT	Texas Instruments	2.495V	36V	±0.5%	—	700µA	-40°C ~ 125°C	Active	SOT-23-3
LM431CIM3	Texas Instruments	2.5V	37V	-0.6%, +0.4%	50ppm/°C	1 mA	-40°C ~ 85°C	Last Time Buy	SOT-23-3
LM431CIM3/NOPB	Texas Instruments	2.5V	37V	-0.6%, +0.4%	50ppm/°C	1 mA	-40°C ~ 85°C	Active	SOT-23-3
LM431CIM3X/NOPB	Texas Instruments	2.5V	37V	-0.6%, +0.4%	50ppm/°C	1 mA	-40°C ~ 85°C	Active	SOT-23-3
AS431HMANTR-G1	Diodes Incorporated	2.495V	36V	±0.5%	20ppm/°C	500µA	-40°C ~ 125°C	Active	SOT-23-3

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications): Select LM431CIM3/NOPB or LM431CIM3X/NOPB when exact parametric matching is required. Both parts maintain identical electrical characteristics and operating temperature range as the LM431CIM3X. LM431CIM3/NOPB and LM431CIM3X/NOPB carry Active product status, ensuring continued availability compared to the Last Time Buy designation of the original part.

For Performance Upgrade with Extended Temperature Range: Select TL431BQDBZR, TL431BQDBZRQ1, or TL431BQDBZT when designs require extended operating temperature range (-40°C ~ 125°C) and improved tolerance specification (±0.5%). All three TL431 variants are Active products with higher inventory availability. TL431BQDBZRQ1 includes AEC-Q100 automotive qualification for applications requiring automotive-grade reliability.

For Superior Performance Characteristics: Select AS431HMANTR-G1 (Diodes Incorporated) when designs benefit from improved temperature coefficient (20ppm/°C) and reduced cathode current (500µA). This part is manufactured by an alternative supplier, providing supply chain diversification while maintaining SOT-23-3 package compatibility and Active product status.

Regulatory Compliance: All substitute parts maintain ROHS3 compliance. The AS431HMANTR-G1 carries MSL 3 (168 Hours) versus MSL 1 (Unlimited) for Texas Instruments parts; this difference affects moisture-sensitive device handling procedures but does not impact electrical performance.

Frequently Asked Questions (FAQ)

Q: Can TL431BQDBZR replace LM431CIM3X in existing designs? A: Yes. Both parts share identical SOT-23-3 pinout, 100 mA output current, and adjustable shunt reference topology. The TL431BQDBZR offers improved tolerance (±0.5% vs. -0.6%, +0.4%) and extended operating temperature range (-40°C ~ 125°C vs. -40°C ~ 85°C). Designs operating within the original -40°C ~ 85°C range experience no functional difference.

Q: What is the difference between LM431CIM3X and LM431CIM3X/NOPB? A: Both parts are electrically and mechanically identical. The "/NOPB" suffix indicates "No Plumbum" (lead-free) packaging designation. Both are ROHS3 compliant. The primary difference is product status: LM431CIM3X is Last Time Buy, while LM431CIM3X/NOPB is Active, ensuring continued availability.

Q: Is AS431HMANTR-G1 a direct substitute for LM431CIM3X? A: Yes, with noted improvements. The AS431HMANTR-G1 maintains SOT-23-3 package compatibility, 100 mA output current, and adjustable shunt reference topology. It offers superior temperature coefficient (20ppm/°C vs. 50ppm/°C) and lower cathode current (500µA vs. 1mA). The maximum output voltage is 36V versus 37V; this difference is negligible for most applications.

Q: Why do TL431 parts show lower maximum output voltage (36V vs. 37V)? A: Both voltage ratings are within acceptable design margins for shunt reference applications. The 1V difference does not affect functional compatibility in standard voltage reference circuits. Designs operating near the 37V maximum should be evaluated for the 36V TL431 rating.

Q: Can I use TL431BQDBZRQ1 in non-automotive applications? A: Yes. TL431BQDBZRQ1 includes AEC-Q100 automotive qualification, which exceeds standard industrial requirements. This part is suitable for any application requiring the TL431 electrical specifications and extended temperature range.

Q: What is the impact of different cathode current specifications? A: Cathode current affects circuit biasing and reference stability. LM431CIM3X requires 1 mA minimum cathode current, while TL431 variants require 700µA and AS431HMANTR-G1 requires 500µA. Lower cathode current requirements provide design flexibility for low-power applications. Existing designs biased for 1 mA operate within specification with lower-cathode-current substitutes.

Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts maintain ROHS3 compliance. Moisture sensitivity levels vary: Texas Instruments parts are MSL 1 (Unlimited), while AS431HMANTR-G1 is MSL 3 (168 Hours). MSL 3 requires standard moisture-sensitive device handling procedures but does not affect electrical performance.

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