Littelfuse Q4004L3 TRIAC Equivalent & Substitute Parts

Part Overview

The Littelfuse Q4004L3 is a Logic-Sensitive Gate TRIAC rated for 400 V off-state voltage and 4 A on-state current in a TO-220 Isolated Tab package. This component is discontinued at DiGi Electronics, necessitating identification of functionally equivalent alternatives that meet or exceed the original specifications while maintaining compatibility with existing circuit designs.

Key Parameters

Parameter	Value
Triac Type	Logic - Sensitive Gate
Voltage - Off State	400 V
Current - On State (It (RMS)) (Max)	4 A
Voltage - Gate Trigger (Vgt) (Max)	1.3 V
Current - Gate Trigger (Igt) (Max)	10 mA
Current - Hold (Ih) (Max)	20 mA
Package / Case	TO-220-3 Isolated Tab
Operating Temperature	-40°C ~ 125°C (TJ)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the Q4004L3 is determined by the following critical parameters:

Triac Type: Must be Logic-Sensitive Gate configuration
Voltage - Off State: Substitute must equal or exceed 400 V
Current - On State: Substitute must equal or exceed 4 A
Gate Trigger Characteristics: Voltage (Vgt) and current (Igt) must be compatible with existing gate drive circuits
Package Compatibility: TO-220 form factor with isolated tab configuration
Temperature Range: Operating range must support -40°C to 125°C minimum

Both identified substitutes (BT137X-600E,127 and BTA06-600SWRG) exceed the voltage and current ratings of the original Q4004L3, providing enhanced performance margins. Both maintain Logic-Sensitive Gate architecture and compatible gate trigger specifications.

Parameter Comparison

Parameter	Q4004L3 (Original)	BT137X-600E,127 (WeEn)	BTA06-600SWRG (STMicroelectronics)
Triac Type	Logic - Sensitive Gate	Logic - Sensitive Gate	Logic - Sensitive Gate
Voltage - Off State	400 V	600 V	600 V
Current - On State (It (RMS)) (Max)	4 A	8 A	6 A
Voltage - Gate Trigger (Vgt) (Max)	1.3 V	1.5 V	1.3 V
Current - Non Rep. Surge 50, 60Hz (Itsm)	46A, 55A	65A, 71A	60A, 63A
Current - Gate Trigger (Igt) (Max)	10 mA	10 mA	10 mA
Current - Hold (Ih) (Max)	20 mA	20 mA	15 mA
Package / Case	TO-220-3 Isolated Tab	TO-220-3 Full Pack, Isolated Tab	TO-220-3
Operating Temperature	-40°C ~ 125°C (TJ)	125°C (TJ)	-40°C ~ 125°C (TJ)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Discontinued at DiGi Electronics	Active	Active

Engineering Selection Recommendations

BTA06-600SWRG (STMicroelectronics) is the primary substitute for the Q4004L3. This part maintains the full operating temperature range (-40°C to 125°C) specified for the original component, matches the gate trigger voltage specification (1.3 V maximum), and provides 50% additional current capacity (6 A vs. 4 A). The part is ROHS3 compliant, REACH unaffected, and currently in active production with high inventory availability (17,304 pcs).

BT137X-600E,127 (WeEn Semiconductors) serves as a secondary substitute with enhanced current rating (8 A) and surge capability. This part is ROHS3 compliant and REACH affected. The specified operating temperature range does not include the lower limit (-40°C), which may restrict use in applications requiring full temperature performance of the original Q4004L3.

Both substitutes are rated for 600 V off-state voltage, providing a 200 V safety margin above the original 400 V specification.

Frequently Asked Questions (FAQ)

Q: Can the BTA06-600SWRG directly replace the Q4004L3 in existing designs?

A: Yes. The BTA06-600SWRG maintains identical gate trigger voltage (1.3 V maximum), matching gate trigger current (10 mA maximum), and full operating temperature range (-40°C to 125°C). The TO-220 package with isolated tab is mechanically and electrically compatible. The higher voltage and current ratings provide performance margin without circuit modification.

Q: What is the difference between the two substitute options?

A: The BTA06-600SWRG maintains the full temperature range and matches the original gate trigger voltage specification. The BT137X-600E,127 provides higher current capacity (8 A vs. 6 A) but specifies only 125°C maximum operating temperature without a lower limit specification. Selection depends on application temperature requirements.

Q: Are both substitutes available in the same package configuration?

A: Both parts use TO-220 packages with isolated tabs. The BTA06-600SWRG uses standard TO-220-3 configuration. The BT137X-600E,127 uses TO-220F (full pack) configuration. Both are mechanically compatible with TO-220 mounting hardware and PCB layouts designed for the Q4004L3.

Q: Do the substitutes maintain RoHS3 compliance?

A: Yes. Both BTA06-600SWRG and BT137X-600E,127 are ROHS3 compliant. The BTA06-600SWRG is REACH unaffected, while the BT137X-600E,127 is REACH affected.

Q: What is the impact of the higher voltage rating on circuit operation?

A: The 600 V off-state voltage rating of both substitutes does not affect circuit operation when applied to designs rated for 400 V. The higher rating provides additional safety margin and transient protection. No circuit modifications are required.

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