ZR431C Equivalent & Substitute Parts

Part Overview

The ZR431C is a shunt voltage reference IC manufactured by Diodes Incorporated, designed for adjustable voltage regulation applications. This device provides a 2.5V to 20V adjustable output with ±2% tolerance and 100 mA output current capability in a TO-92 through-hole package. The ZR431C is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility across reference voltage, output current, tolerance, and temperature coefficient specifications while accommodating different packaging formats.

Substiute Parts

ZR431C

Diodes IncorporatedIn Stock: 858ZR431C Datasheet

Current PartRFQ

ZR431FTA

Diodes IncorporatedIn Stock: 15507ZR431FTA Datasheet

MFR RecommendedRFQ

TL431ILP

onsemiIn Stock: 889219TL431ILP Datasheet

DirectRFQ

LM431AIZ/NOPB

Texas InstrumentsIn Stock: 1820LM431AIZ/NOPB Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the ZR431C is determined by the following critical parameters:

Electrical Compatibility Requirements:

• Reference type must be shunt
• Output type must be adjustable
• Minimum output voltage must be ≤2.5V
• Maximum output voltage must be ≥20V
• Output current must be ≥100 mA
• Tolerance must be ≤±2%
• Temperature coefficient must be ≤55 ppm/°C
• Operating temperature range must encompass -40°C to 85°C

Packaging Considerations:

• Through-hole mounting (TO-92 package family) maintains PCB compatibility
• Surface-mount alternatives (SOT-23) require board redesign but offer active product status

The substitute parts are grouped into two categories: direct through-hole replacements maintaining identical mounting characteristics, and surface-mount alternatives providing enhanced availability and active product support.

Parameter Comparison

Engineering Selection Recommendations

For Through-Hole PCB Designs (No Board Redesign):

LM431AIZ/NOPB from Texas Instruments is the primary substitute for ZR431C. Both devices maintain TO-92-3 through-hole packaging, ensuring direct PCB compatibility without layout modifications. LM431AIZ/NOPB carries active product status and ROHS3 compliance, providing long-term supply assurance and regulatory alignment. The tolerance specification of ±2.2% and temperature coefficient of 50 ppm/°C (typical) meet or exceed ZR431C performance requirements. Maximum output voltage of 37V exceeds the 20V requirement, providing design margin for higher-voltage applications.

TL431ILP from onsemi is an alternative through-hole option with identical TO-92-3 packaging. However, this device is classified as obsolete and carries RoHS non-compliance status, limiting its suitability for new designs requiring regulatory compliance.

For Surface-Mount PCB Designs (Board Redesign Acceptable):

ZR431FTA from Diodes Incorporated is the manufacturer-recommended upgrade path, offering active product status and ROHS3 compliance in SOT-23-3 surface-mount packaging. Electrical specifications are identical to ZR431C (2.5V to 20V output, ±2% tolerance, 55 ppm/°C temperature coefficient). This option requires PCB redesign but provides superior component availability (15,431 units in stock) and ensures long-term supply continuity from the original manufacturer.

Compliance Considerations:

For applications requiring ROHS3 compliance, LM431AIZ/NOPB and ZR431FTA are the only viable options. TL431ILP does not meet RoHS requirements and should be avoided in regulated applications.

Frequently Asked Questions (FAQ)

Q: Can ZR431C be directly replaced with ZR431FTA without circuit modifications?

A: ZR431FTA is electrically equivalent to ZR431C but requires PCB redesign due to package format change from TO-92-3 (through-hole) to SOT-23-3 (surface-mount). Pin assignments differ between packages, necessitating layout modifications.

Q: What is the difference between ±2% and ±2.2% tolerance specifications?

A: Tolerance defines the maximum deviation of output voltage from the nominal value across operating conditions. ZR431C and ZR431FTA specify ±2%, while TL431ILP and LM431AIZ/NOPB specify ±2.2%. For applications requiring tighter voltage regulation, ZR431C and ZR431FTA are preferred. Both tolerances are acceptable for general voltage reference applications.

Q: Why does LM431AIZ/NOPB have a higher maximum output voltage (37V) than ZR431C (20V)?

A: Maximum output voltage represents the highest voltage the device can regulate without damage. LM431AIZ/NOPB's higher rating provides greater design flexibility for applications requiring higher reference voltages. Circuits designed for 20V operation remain fully compatible with this device.

Q: Is cathode current (50 µA vs. 1 mA) a critical substitution parameter?

A: Cathode current affects minimum load requirements for stable operation. ZR431C requires 50 µA minimum cathode current, while TL431ILP and LM431AIZ/NOPB require 1 mA. Designs must ensure adequate load current to meet the higher requirement when using onsemi or Texas Instruments devices. This is a design consideration rather than a compatibility barrier.

Q: Which substitute part offers the best long-term availability?

A: ZR431FTA provides the highest inventory level (15,431 units) and active product status from the original manufacturer, ensuring long-term supply continuity. LM431AIZ/NOPB from Texas Instruments also carries active status with 1,807 units in stock. Both TL431ILP and ZR431C are obsolete and face supply constraints.

Q: Can TL431ILP be used in new designs despite RoHS non-compliance?

A: TL431ILP is not recommended for new designs. Its obsolete status and RoHS non-compliance create regulatory and supply chain risks. LM431AIZ/NOPB or ZR431FTA are superior alternatives meeting current compliance requirements.