Q8008RH4 TRIAC Alternistor 800V 8A TO-220 Equivalent & Substitute Parts

Part Overview

The Q8008RH4 is a TRIAC Alternistor (snubberless) rated for 800 V off-state voltage and 8 A on-state current in a Through Hole TO-220 package. Manufactured by Littelfuse Inc., this component is discontinued at DiGi Electronics. Equivalent and substitute parts must maintain the same voltage rating, current capacity, and package configuration while meeting RoHS3 compliance and MSL Level 1 requirements.

Key Parameters

Parameter	Q8008RH4
Manufacturer	Littelfuse Inc.
Category	Thyristors - TRIAC
Voltage - Off State	800 V
Current - On State (It RMS Max)	8 A
Voltage - Gate Trigger (Vgt Max)	1.3 V
Current - Gate Trigger (Igt Max)	35 mA
Current - Hold (Ih Max)	35 mA
Current - Non Rep. Surge (50/60Hz)	83 A / 100 A
Operating Temperature Range	-40°C to 125°C (TJ)
Mounting Type	Through Hole
Package / Case	TO-220-3
Configuration	Single
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the Q8008RH4 is determined by the following critical parameters:

Voltage Rating: 800 V off-state voltage is mandatory
Current Rating: On-state current must be 8 A or greater
Package: TO-220-3 Through Hole configuration required
Gate Trigger Characteristics: Vgt and Igt values must be compatible with circuit design
Temperature Range: Operating temperature capability must meet or exceed -40°C to 125°C
Compliance: RoHS3 compliance and MSL Level 1 required

Substitute parts are grouped by TRIAC type (Alternistor - Snubberless, Logic - Sensitive Gate, or Standard) and current rating. Parts with 8 A, 10 A, or 12 A ratings are acceptable substitutes provided all other parameters align with application requirements.

Parameter Comparison

Part Number	Manufacturer	TRIAC Type	Voltage (V)	Current (A)	Vgt Max (V)	Igt Max (mA)	Ih Max (mA)	Temp Range (°C)	Package	Status
Q8008RH4	Littelfuse Inc.	Alternistor - Snubberless	800	8	1.3	35	35	-40 to 125	TO-220-3	Discontinued
ACST610-8T	STMicroelectronics	Logic - Sensitive Gate	800	6	1.0	10	25	-40 to 125	TO-220-3	Active
ACTT10-800CTNQ	WeEn Semiconductors	Standard	800	10	1.0	35	30	-40 to 150	TO-220-3	Active
ACTT8-800C0TQ	WeEn Semiconductors	Standard	800	8	1.0	30	35	-40 to 150	TO-220-3	Active
BT138-800,127	WeEn Semiconductors	Standard	800	12	1.5	35	30	-40 to 125	TO-220-3	Active
BT138-800/DG,127	NXP USA Inc.	Standard	800	12	1.5	35	30	-40 to 125	TO-220-3	Active
BT138-800E,127	WeEn Semiconductors	Logic - Sensitive Gate	800	12	1.5	10	30	-40 to 125	TO-220-3	Active
BTA310-800C,127	WeEn Semiconductors	Standard	800	10	1.5	35	35	-40 to 125	TO-220-3	Active
BTA312-800C,127	WeEn Semiconductors	Standard	800	12	1.5	35	35	-40 to 125	TO-220-3	Active
BTA312-800C/DG,127	WeEn Semiconductors	Standard	800	12	1.5	35	35	-40 to 125	TO-220-3	Active
BTA312-800CT,127	WeEn Semiconductors	Standard	800	12	1.0	35	35	-40 to 150	TO-220-3	Active

Engineering Selection Recommendations

Direct Current-Matched Substitutes (8 A Rating)

ACTT8-800C0TQ from WeEn Semiconductors is the closest functional equivalent. It maintains the 8 A on-state current rating, 800 V voltage class, and TO-220-3 package. This part is Active status with extended operating temperature range (-40°C to 150°C) and RoHS3 compliance. Gate trigger voltage is lower (1.0 V vs. 1.3 V), which may require circuit verification for gate drive compatibility.

Higher Current Substitutes (10 A and 12 A Ratings)

ACTT10-800CTNQ, BT138-800,127, BT138-800/DG,127, BTA310-800C,127, BTA312-800C,127, BTA312-800C/DG,127, and BTA312-800CT,127 all provide higher current capacity while maintaining 800 V voltage rating and TO-220-3 package. These are suitable when circuit design permits higher current handling. All are Active status with RoHS3 compliance.

Lower Current Substitute (6 A Rating)

ACST610-8T from STMicroelectronics is rated for 6 A on-state current. This part is suitable only if circuit design does not require the full 8 A capacity. It features sensitive gate characteristics (Igt 10 mA) and is Active status with RoHS3 compliance.

Compliance and Availability

All substitute parts listed are Active status with RoHS3 compliance and MSL Level 1 rating. Inventory availability ranges from 750 to 7068 units across suppliers, ensuring supply chain continuity.

Frequently Asked Questions (FAQ)

Q: Can ACST610-8T (6 A) replace Q8008RH4 (8 A)?

A: ACST610-8T is rated for 6 A on-state current, which is below the Q8008RH4 specification. Use this part only if your circuit design does not require 8 A capacity. The lower gate trigger current (10 mA vs. 35 mA) also requires gate drive circuit verification.

Q: What is the difference between Standard and Logic - Sensitive Gate TRIAC types?

A: Logic - Sensitive Gate TRIACs (ACST610-8T, BT138-800E,127) require lower gate trigger current (10 mA) compared to Standard types (30-35 mA). Standard TRIACs provide more robust gate triggering. Select based on your gate drive circuit capability.

Q: Can I use a 12 A rated TRIAC (BT138-800,127 or BTA312-800C,127) instead of the 8 A Q8008RH4?

A: Yes. Higher current-rated TRIACs are backward compatible in circuits designed for lower current. All listed 12 A substitutes maintain 800 V voltage rating and TO-220-3 package. Verify gate trigger voltage compatibility (1.5 V for BT138 and BTA312 series vs. 1.3 V for Q8008RH4).

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed are RoHS3 compliant with MSL Level 1 (Unlimited) moisture sensitivity rating, matching the Q8008RH4 compliance profile.

Q: What is the difference between BT138-800,127 and BT138-800/DG,127?

A: Both parts are identical in electrical specifications (800 V, 12 A, Standard TRIAC type, TO-220-3 package). The difference is packaging: BT138-800,127 is supplied in Tube, while BT138-800/DG,127 is supplied in Bulk. Select based on your procurement and handling requirements.

Q: Does operating temperature range affect substitution?

A: The Q8008RH4 operates from -40°C to 125°C. ACTT10-800CTNQ, ACTT8-800C0TQ, and BTA312-800CT,127 extend to 150°C, providing additional thermal margin. Other substitutes match the 125°C upper limit. Select based on your application's thermal environment.

Q: Can I substitute Q8008RH4 with ACST610-8T if my circuit only needs 6 A?

A: Yes, if your circuit design confirms that 6 A capacity is sufficient. However, verify gate drive compatibility: ACST610-8T requires only 10 mA gate trigger current versus 35 mA for Q8008RH4. Your gate drive circuit must be capable of delivering the lower current requirement.

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