1N4112-TP Equivalent & Substitute Parts

Part Overview

The 1N4112-TP is a Zener diode rated at 18 V nominal with 500 mW power dissipation in a DO-35 through-hole package. Manufactured by Micro Commercial Co, this component is classified as obsolete. Due to its obsolete status and limited inventory availability (870 pieces), identification of active equivalent and substitute parts is necessary for ongoing design support and production continuity. Substitute parts listed below maintain the core electrical specifications while offering active product status and improved availability from alternative manufacturers.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	18	V
Tolerance	±5%	-
Power - Max	500	mW
Package / Case	DO-204AH, DO-35, Axial	-
Mounting Type	Through Hole	-
Operating Temperature	Up to 175	°C
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution of the 1N4112-TP is determined by the following critical parameters:

Primary Matching Criteria:

Voltage - Zener (Nom): 18 V
Power - Max: 500 mW
Package / Case: DO-35 (DO-204AH)
Mounting Type: Through Hole

Secondary Compatibility Factors:

Tolerance: ±5% or tighter (±2%)
Impedance (Max): Varies by part; lower impedance indicates improved performance characteristics
Current - Reverse Leakage: Specified at rated voltage
Voltage - Forward (Vf): Maximum 1.1 V @ 200 mA
RoHS3 Compliance: Required for regulatory alignment

Substitute parts are grouped into two categories based on tolerance specification:

Category A - ±5% Tolerance (Direct Functional Equivalents): Parts maintaining ±5% tolerance match the original specification exactly. These include 1N5248B variants and BZX55C18 series.

Category B - ±2% Tolerance (Enhanced Precision Alternatives): Parts with ±2% tolerance provide tighter voltage regulation. These include 1N5248C variants and BZX55B18 series. Enhanced tolerance does not prevent substitution; it represents an improvement in voltage accuracy.

All substitute parts maintain DO-35 through-hole packaging, 500 mW power rating, and 18 V nominal zener voltage. Differences in impedance and reverse leakage current reflect manufacturing variations between suppliers but do not preclude functional substitution within the specified electrical envelope.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Ir @ Vr	Vf (Max)	Status	Package
1N4112-TP	Micro Commercial Co	18 V	±5%	500 mW	100 Ω	50 nA @ 13.67 V	1.1 V @ 200 mA	Obsolete	DO-35
1N5248B-TAP	Vishay General Semiconductor	18 V	±5%	500 mW	21 Ω	100 nA @ 14 V	1.1 V @ 200 mA	Active	DO-35
1N5248B BK PBFREE	Central Semiconductor Corp	18 V	±5%	500 mW	21 Ω	100 nA @ 14 V	1.1 V @ 200 mA	Active	DO-35
1N5248B TR PBFREE	Central Semiconductor Corp	18 V	±5%	500 mW	21 Ω	100 nA @ 14 V	1.1 V @ 200 mA	Active	DO-35
1N5248B-TR	Vishay General Semiconductor	18 V	±5%	500 mW	21 Ω	100 nA @ 14 V	1.1 V @ 200 mA	Active	DO-35
1N5248C-TAP	Vishay General Semiconductor	18 V	±2%	500 mW	21 Ω	100 nA @ 14 V	1.1 V @ 200 mA	Active	DO-35
1N5248C-TR	Vishay General Semiconductor	18 V	±2%	500 mW	21 Ω	100 nA @ 14 V	1.1 V @ 200 mA	Active	DO-35
BZX55B18-TAP	Vishay General Semiconductor	18 V	±2%	500 mW	50 Ω	100 nA @ 13 V	1.5 V @ 200 mA	Active	DO-35
BZX55B18-TR	Vishay General Semiconductor	18 V	±2%	500 mW	50 Ω	100 nA @ 13 V	1.5 V @ 200 mA	Active	DO-35
BZX55C18-TAP	Vishay General Semiconductor	18 V	±5%	500 mW	50 Ω	100 nA @ 13 V	1.5 V @ 200 mA	Active	DO-35

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

The 1N5248B series (1N5248B-TAP, 1N5248B-TR, 1N5248B TR PBFREE, 1N5248B BK PBFREE) from Vishay General Semiconductor and Central Semiconductor Corp are direct functional equivalents. These parts maintain ±5% tolerance matching the original specification, identical 18 V zener voltage, 500 mW power rating, and DO-35 packaging. All are active products with substantial inventory availability. Vishay parts carry AEC-Q101 automotive qualification and REACH compliance. Central Semiconductor parts provide extended operating temperature range (-65°C to 200°C) compared to the original specification.

Secondary Substitutes (Enhanced Precision):

The 1N5248C series (1N5248C-TAP, 1N5248C-TR) offers ±2% tolerance, providing tighter voltage regulation than the original ±5% specification. These Vishay parts are AEC-Q101 qualified and REACH compliant. The improved tolerance does not compromise substitution; it represents enhanced performance for applications requiring tighter voltage control.

Alternative Substitutes (Different Impedance Characteristics):

The BZX55B18 and BZX55C18 series from Vishay maintain 18 V zener voltage and 500 mW power rating but feature higher impedance (50 Ω versus 21 Ω in 1N5248 series). BZX55B18 variants provide ±2% tolerance; BZX55C18 variants provide ±5% tolerance. These parts carry AEC-Q101 qualification and REACH compliance. Higher impedance may affect circuit performance in applications sensitive to dynamic impedance characteristics.

Product Status Consideration:

All substitute parts listed are active products with confirmed inventory availability, eliminating obsolescence risk associated with the original 1N4112-TP. Selection should prioritize active parts based on specific packaging requirements (Cut Tape, Tape & Reel, or Bulk) and tolerance specifications required by the application.

Frequently Asked Questions (FAQ)

Q: Can 1N5248B parts directly replace 1N4112-TP in existing designs?

A: Yes. The 1N5248B series maintains identical zener voltage (18 V), power rating (500 mW), tolerance (±5%), and DO-35 through-hole packaging. Electrical performance is functionally equivalent. The primary difference is lower impedance (21 Ω versus 100 Ω), which generally improves circuit performance by reducing dynamic impedance effects.

Q: What is the difference between ±5% and ±2% tolerance variants?

A: Tolerance specifies the allowable deviation of the zener voltage from the nominal 18 V rating. ±5% tolerance allows deviation between 17.1 V and 18.9 V; ±2% tolerance allows deviation between 17.64 V and 18.36 V. Applications requiring tighter voltage regulation benefit from ±2% parts. ±2% variants are functionally compatible with ±5% designs and do not require circuit modification.

Q: Why do impedance values differ between substitute parts?

A: Impedance (Zzt) reflects the dynamic resistance of the zener diode at specified operating conditions. Lower impedance (21 Ω in 1N5248 series) indicates better voltage regulation and reduced voltage ripple. Higher impedance (50 Ω in BZX55 series) may introduce greater voltage variation under load changes. Selection depends on circuit requirements for voltage stability.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed are RoHS3 compliant, matching the original 1N4112-TP specification. This ensures compatibility with regulatory requirements for lead-free manufacturing and hazardous substance restrictions.

Q: What packaging options are available for substitutes?

A: Substitute parts are available in three packaging formats: Cut Tape (CT), Tape & Reel (TR), and Bulk. Cut Tape is suitable for small-quantity assembly; Tape & Reel accommodates automated pick-and-place equipment; Bulk packaging is used for manual assembly or high-volume operations. All maintain identical DO-35 through-hole component geometry.

Q: Do substitute parts carry automotive qualification?

A: Vishay 1N5248B, 1N5248C, BZX55B18, and BZX55C18 parts carry AEC-Q101 automotive qualification. Central Semiconductor 1N5248B variants do not list AEC-Q101 qualification but are active products with REACH compliance. Automotive applications should specify Vishay-qualified parts.

Q: Can BZX55 series parts substitute for 1N5248 series?

A: Yes, with impedance considerations. Both series maintain 18 V zener voltage, 500 mW power rating, and DO-35 packaging. BZX55 parts feature higher impedance (50 Ω) compared to 1N5248 parts (21 Ω). This difference affects voltage regulation characteristics. Applications sensitive to dynamic impedance should evaluate circuit performance with higher impedance parts.

Q: What is the operating temperature range for substitute parts?

A: Operating temperature varies by manufacturer. Vishay parts specify -65°C to 175°C; Central Semiconductor 1N5248B variants specify -65°C to 200°C. The original 1N4112-TP specifies operation to 175°C. Applications requiring extended high-temperature operation benefit from Central Semiconductor parts with 200°C maximum rating.

Q: Are substitute parts available in sufficient quantity?

A: Yes. Inventory availability for active substitute parts ranges from 905 to 45,679 pieces across all variants, substantially exceeding the 870 pieces available for the obsolete 1N4112-TP. This ensures reliable supply for production and design continuity.

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