S4040NQ2TP Equivalent & Substitute Parts

Part Overview

The S4040NQ2TP is a Silicon Controlled Rectifier (SCR) rated for 400V off-state voltage with 40A RMS on-state current capability, manufactured by Littelfuse Inc. in a Surface Mount TO-263 (D2PAK) package. This component is classified as Obsolete, making identification of equivalent and substitute parts essential for ongoing design support and production continuity. The part operates across a temperature range of -40°C to 125°C and complies with ROHS3 standards.

Key Parameters

Parameter	Value	Unit
Voltage - Off State	400	V
Current - On State (It (RMS))	40	A
Voltage - Gate Trigger (Vgt) (Max)	1.5	V
Current - Gate Trigger (Igt) (Max)	40	mA
Voltage - On State (Vtm) (Max)	1.8	V
Current - Hold (Ih) (Max)	60	mA
Operating Temperature Range	-40 to 125	°C
Package / Case	TO-263-3, D2PAK	-
Mounting Type	Surface Mount	-
SCR Type	Standard Recovery	-

Substitute Part Grouping Explanation

Substitution for the S4040NQ2TP is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Off-state voltage rating (400V minimum)
On-state current capability (RMS rating)
Gate trigger voltage and current specifications
On-state voltage drop characteristics
Package compatibility (TO-263 / D2PAK surface mount)
SCR type classification (Standard Recovery)
Operating temperature range (-40°C to 125°C)

Substitute Parts Identified:

S4040NTP - Parametric equivalent with identical electrical specifications. Differs only in packaging format (Tube vs. unspecified for main part) and product status (Active vs. Obsolete). All critical electrical parameters match exactly.
S4055NTP - Parametric equivalent with higher on-state current rating (55A RMS vs. 40A RMS). Maintains identical off-state voltage, gate trigger specifications, and package type. Non-repetitive surge current capability increased proportionally (550A/650A vs. 430A/520A). Suitable for applications requiring higher current capacity within the same voltage class.

Parameter Comparison

Parameter	S4040NQ2TP (Main)	S4040NTP (Substitute)	S4055NTP (Substitute)
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.
Voltage - Off State	400 V	400 V	400 V
Current - On State (It (RMS))	40 A	40 A	55 A
Current - On State (It (AV))	25 A	25 A	35 A
Voltage - Gate Trigger (Vgt) (Max)	1.5 V	1.5 V	1.5 V
Current - Gate Trigger (Igt) (Max)	40 mA	40 mA	40 mA
Voltage - On State (Vtm) (Max)	1.8 V	1.8 V	1.8 V
Current - Hold (Ih) (Max)	60 mA	60 mA	60 mA
Current - Off State (Max)	10 µA	10 µA	10 µA
SCR Type	Standard Recovery	Standard Recovery	Standard Recovery
Operating Temperature	-40 to 125 °C	-40 to 125 °C	-40 to 125 °C
Package / Case	TO-263-3, D2PAK	TO-263-3, D2PAK	TO-263-3, D2PAK
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

S4040NTP Selection: This part is the direct electrical equivalent to the S4040NQ2TP with Active product status. Selection of S4040NTP is appropriate for applications requiring exact current and voltage specifications. The transition from Obsolete to Active status ensures long-term supply chain availability and manufacturing support. Both parts maintain identical gate trigger characteristics and on-state voltage performance. ROHS3 compliance and MSL Level 1 rating are preserved.

S4055NTP Selection: This part provides increased on-state current capacity (55A RMS vs. 40A RMS) while maintaining all other electrical parameters. Selection is appropriate for applications where the original 40A rating provides insufficient margin or where higher current handling is required within the same 400V voltage class. The higher surge current rating (550A/650A) provides additional transient protection capability. Product status is Active with equivalent compliance certifications.

Both substitute parts are manufactured by Littelfuse Inc. and maintain the same TO-263 surface mount package configuration, ensuring mechanical and thermal compatibility with existing PCB designs.

Frequently Asked Questions (FAQ)

Q: Can S4040NTP be used as a direct replacement for S4040NQ2TP?

A: Yes. S4040NTP is a parametric equivalent with identical electrical specifications across all critical parameters: 400V off-state voltage, 40A RMS on-state current, 1.5V gate trigger voltage, and 1.8V on-state voltage drop. The only differences are packaging format and product status (Active vs. Obsolete). Mechanical compatibility is maintained through identical TO-263 D2PAK packaging.

Q: When should S4055NTP be selected instead of S4040NTP?

A: S4055NTP should be selected when the application requires higher on-state current capacity. The 55A RMS rating (vs. 40A RMS) provides increased current handling with proportionally higher surge current capability (550A/650A vs. 430A/520A). All other electrical characteristics remain identical. This part is suitable for designs where current margin or thermal headroom is a design consideration.

Q: Are there any compatibility concerns when substituting these parts?

A: No compatibility concerns exist for direct substitution. All three parts share identical gate trigger specifications (1.5V Vgt, 40A Igt), on-state voltage characteristics (1.8V Vtm), and hold current requirements (60mA Ih). The TO-263 D2PAK package is identical across all parts, ensuring PCB layout and thermal management compatibility.

Q: What is the difference in packaging between S4040NQ2TP and S4040NTP?

A: The primary difference is the supplier device package designation. S4040NQ2TP packaging is unspecified in the provided data, while S4040NTP is supplied in Tube packaging. Both use the TO-263 (D2PAK) case style with identical lead configuration and thermal characteristics.

Q: Do all substitute parts meet the same compliance standards?

A: Yes. S4040NTP and S4055NTP both maintain ROHS3 compliance, MSL Level 1 rating, and identical ECCN (EAR99) and HTSUS classifications as the original S4040NQ2TP. Temperature operating range (-40°C to 125°C) is preserved across all parts.

Q: What is the inventory status for these substitute parts?

A: S4040NTP has 840 pieces in stock and S4055NTP has 1119 pieces in stock, both listed as New Original. The original S4040NQ2TP has 732 pieces available but is classified as Obsolete.

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