MC34166TH Equivalent & Substitute Parts

Part Overview

The MC34166TH is a Buck, Boost Switching Regulator IC manufactured by onsemi, designed for positive or negative adjustable output applications. This integrated circuit provides step-up and step-down voltage regulation with a fixed output of 5.05V and maximum switchable current of 3.3A. The device is housed in a TO-220-5 through-hole package with formed leads.

The MC34166TH is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support legacy system maintenance or redesign initiatives.

Substiute Parts

MC34166TH

onsemiIn Stock: 6302MC34166TH Datasheet

Current PartRFQ

MC34166THG

onsemiIn Stock: 6056MC34166THG Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the MC34166TH is determined by strict equivalence across the following critical parameters:

• Topology: Buck, Boost configuration
• Output Configuration: Positive or Negative adjustable
• Voltage specifications: Input range 7.5V to 40V; Output 5.05V fixed minimum to 40V maximum
• Current rating: 3.3A switchable output
• Switching frequency: 72kHz
• Package: TO-220-5 through-hole with formed leads
• Synchronous rectifier: Not present

The MC34166THG is a direct substitute manufactured by onsemi under the same base product number (MC34166). Both devices share identical electrical specifications and package configuration. The primary distinction is packaging format: MC34166TH is supplied in tape format, while MC34166THG is supplied in tube format.

Parameter Comparison

Engineering Selection Recommendations

Both MC34166TH and MC34166THG are functionally equivalent devices from onsemi's MC34166 product line. Selection between these parts should be based on the following criteria:

MC34166THG is the preferred choice for new designs or systems requiring regulatory compliance. This variant achieves ROHS3 compliance, meeting current environmental and material restriction standards. The tube packaging format is suitable for automated assembly processes.

MC34166TH remains suitable for legacy system maintenance where existing designs are already qualified to this specific part number and packaging format. However, the RoHS non-compliant status should be evaluated against current procurement and regulatory requirements.

Both devices are classified as obsolete products. For new development initiatives, evaluation of current-generation buck-boost regulator alternatives from onsemi or other manufacturers is recommended to ensure long-term supply chain viability and access to enhanced feature sets.

Frequently Asked Questions (FAQ)

Q: Can MC34166THG be used as a direct replacement for MC34166TH in existing designs?

A: Yes. Both parts share identical electrical specifications, switching characteristics, and TO-220-5 package configuration. The only difference is packaging format (tape versus tube). No circuit modifications are required for substitution.

Q: What is the significance of the RoHS compliance difference between these parts?

A: MC34166THG meets ROHS3 compliance standards, restricting hazardous substances in manufacturing. MC34166TH does not meet this standard. For applications subject to environmental regulations or customer requirements mandating RoHS compliance, MC34166THG is the appropriate selection.

Q: Are there any thermal or performance differences between MC34166TH and MC34166THG?

A: No. Both devices operate within the same temperature range (0°C to 70°C) and deliver identical electrical performance. Thermal characteristics and switching behavior are equivalent.

Q: What does "obsolete" product status mean for these parts?

A: Obsolete status indicates that onsemi has discontinued active production and support for this product line. Existing inventory may be available through authorized distributors, but long-term availability is not guaranteed. For applications requiring sustained supply, evaluation of current-generation alternatives is necessary.

Q: Is the TO-220-5 package still widely supported for new PCB designs?

A: The TO-220-5 through-hole package remains in use for legacy and specialized applications. However, modern power management designs increasingly utilize surface-mount packages for improved thermal performance and board density. For new designs, current-generation buck-boost regulators in smaller packages should be evaluated.