LC5556LD LED Driver IC Equivalent & Substitute Parts

Part Overview

The LC5556LD is an AC DC offline switcher LED driver IC manufactured by Sanken Electric USA Inc., designed for step-down (buck) topology applications with internal switching capability. This 8-DIP through-hole component operates across a supply voltage range up to 18V and is rated for -55°C to 125°C operating temperature. The part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. Substitute parts maintain functional equivalence as AC DC offline switcher LED drivers while offering active product status and extended availability.

Key Parameters

Parameter	LC5556LD Value
Category	Power Management (PMIC)
Type	AC DC Offline Switcher
Topology	Step-Down (Buck)
Internal Switch(s)	Yes
Number of Outputs	1
Voltage - Supply (Max)	18V
Operating Temperature	-55°C ~ 125°C (TA)
Mounting Type	Through Hole
Package / Case	8-DIP (0.300", 7.62mm), 7 Leads
Product Status	Obsolete
RoHS Status	RoHS Compliant
MSL Rating	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution logic for the LC5556LD is based on the following critical parameters that define functional equivalence:

Primary Substitution Criteria:

Type: AC DC Offline Switcher (mandatory)
Topology: Step-Down (Buck) or compatible topologies (Flyback acceptable for functional equivalence)
Number of Outputs: 1 (single output requirement)
Internal Switch(s): Yes (integrated switching capability preferred)
RoHS Compliance: ROHS3 or RoHS Compliant (regulatory requirement)

Secondary Compatibility Factors:

Voltage Supply Range: Maximum supply voltage ≥ 18V or compatible input voltage specification
Operating Temperature: Minimum -40°C and maximum ≥ 125°C preferred
Mounting Type: Surface mount or through-hole acceptable depending on application requirements
Package compatibility: Electrical function takes precedence over package form factor

Substitute parts are grouped into two categories: direct topology matches (step-down buck) and functional equivalents (flyback topology with equivalent output capability). All listed substitutes maintain AC DC offline switcher functionality and single-output configuration.

Parameter Comparison

Part Number	Manufacturer	Type	Topology	Internal Switch	Supply Max (V)	Operating Temp (°C)	Package	Mounting	Product Status	RoHS Status
LC5556LD	Sanken Electric USA Inc.	AC DC Offline Switcher	Step-Down (Buck)	Yes	18	-55 ~ 125	8-DIP	Through Hole	Obsolete	RoHS Compliant
FL7701MX	Fairchild Semiconductor	AC DC Offline Switcher	Step-Down (Buck)	No	20	-40 ~ 125	8-SOIC	Surface Mount	Active	Not Specified
LM3445MX/NOPB	Texas Instruments	AC DC Offline Switcher	Step-Down (Buck)	No	12	-40 ~ 125	14-SOIC	Surface Mount	Active	ROHS3 Compliant
LNK414LG	Power Integrations	AC DC Offline Switcher	Flyback	Yes	725	-40 ~ 150	eSIP-7F	Through Hole	Active	RoHS Compliant
LT3799IMSE-1#PBF	Analog Devices Inc.	AC DC Offline Switcher	Flyback	No	Not Specified	-40 ~ 125	16-MSOP-EP	Surface Mount	Active	ROHS3 Compliant
LYT1403D-TL	Power Integrations	AC DC Offline Switcher	Step-Down (Buck)	Yes	308VAC	-40 ~ 125	8SO	Surface Mount	Active	RoHS Compliant
MP4050AGS-Z	Monolithic Power Systems Inc.	AC DC Offline Switcher	Step-Down (Buck)	Yes	5	-40 ~ 125	8-SOIC	Surface Mount	Active	ROHS3 Compliant
MP4050GS	Monolithic Power Systems Inc.	AC DC Offline Switcher	Step-Down (Buck)	Yes	265VAC	-40 ~ 125	8-SOIC	Surface Mount	Active	ROHS3 Compliant
RT8487GJ6	Richtek USA Inc.	AC DC Offline Switcher	Step-Down (Buck)	No	30	-40 ~ 85	TSOT-23-6	Surface Mount	Active	ROHS3 Compliant
TPS92002DR	Texas Instruments	AC DC Offline Switcher	Flyback, Step-Down (Buck)	No	21	-40 ~ 85	8-SOIC	Surface Mount	Last Time Buy	ROHS3 Compliant

Engineering Selection Recommendations

Active Product Status Substitutes (Preferred): FL7701MX, LM3445MX/NOPB, LNK414LG, LT3799IMSE-1#PBF, LYT1403D-TL, MP4050AGS-Z, MP4050GS, and RT8487GJ6 are all active products with current manufacturing support and extended availability. These parts carry ROHS3 or RoHS Compliant certifications, meeting current regulatory requirements.

Topology-Matched Substitutes (Step-Down Buck): FL7701MX, LM3445MX/NOPB, LYT1403D-TL, MP4050AGS-Z, MP4050GS, and RT8487GJ6 maintain identical step-down (buck) topology to the LC5556LD. These parts provide the closest functional equivalence for direct replacement in existing designs.

Internal Switch Capability: LNK414LG, LYT1403D-TL, MP4050AGS-Z, and MP4050GS retain internal switching capability matching the LC5556LD specification. These parts eliminate the need for external switching components.

Temperature Range Considerations: LNK414LG offers the widest operating temperature range (-40°C to 150°C), exceeding the LC5556LD specification. FL7701MX, LM3445MX/NOPB, LYT1403D-TL, MP4050AGS-Z, and MP4050GS all support the full -40°C to 125°C range. RT8487GJ6 and TPS92002DR are limited to -40°C to 85°C.

Mounting Type Transition: LNK414LG maintains through-hole mounting (eSIP-7F package) for direct PCB compatibility. All other active substitutes use surface-mount packages (SOIC, MSOP, or TSOT-23), requiring PCB redesign for implementation.

Last Time Buy Status: TPS92002DR carries Last Time Buy status, indicating limited remaining availability. This part should be avoided for new designs requiring long-term supply assurance.

Frequently Asked Questions (FAQ)

Q: Can I use a flyback topology part as a substitute for the step-down (buck) LC5556LD?

A: Flyback topology parts (LNK414LG, LT3799IMSE-1#PBF, TPS92002DR) provide functional equivalence as AC DC offline switchers but operate on different circuit principles. Substitution requires circuit redesign and validation. Direct topology matching (step-down buck) is preferred for minimal design changes.

Q: What is the primary reason the LC5556LD is obsolete?

A: The LC5556LD is classified as obsolete by the manufacturer. All listed substitute parts are active products with current production and extended availability, making them suitable for new designs and production continuity.

Q: Does package type affect substitution compatibility?

A: Package type does not affect electrical function but requires PCB layout modifications. The LC5556LD uses 8-DIP through-hole packaging. Surface-mount substitutes (SOIC, MSOP, TSOT-23) require PCB redesign. LNK414LG maintains through-hole compatibility with eSIP-7F packaging.

Q: Which substitute offers the best supply voltage compatibility with the LC5556LD?

A: FL7701MX (20V max), LYT1403D-TL (308VAC), and MP4050GS (265VAC) all exceed or match the LC5556LD 18V maximum supply specification. MP4050AGS-Z is limited to 5V maximum and is suitable only for low-voltage applications.

Q: Are all substitute parts RoHS compliant?

A: All listed substitutes carry either RoHS Compliant or ROHS3 Compliant certification. FL7701MX does not specify RoHS status in available documentation. Verify RoHS compliance with the manufacturer for FL7701MX before final selection.

Q: What is the difference between internal and external switching capability?

A: Internal switch parts (LNK414LG, LYT1403D-TL, MP4050AGS-Z, MP4050GS) integrate the switching transistor on-chip, reducing external component count. External switch parts (FL7701MX, LM3445MX/NOPB, LT3799IMSE-1#PBF, RT8487GJ6, TPS92002DR) require discrete switching components, increasing circuit complexity.

Q: Which substitute has the widest operating temperature range?

A: LNK414LG supports -40°C to 150°C, exceeding the LC5556LD range of -55°C to 125°C. For applications requiring the full -55°C minimum, verify that substitute parts meet this specification, as most active substitutes are limited to -40°C minimum.

Q: Can I use MP4050AGS-Z as a direct replacement for high-voltage applications?

A: No. MP4050AGS-Z is rated for maximum 5V supply voltage and is designed for low-voltage applications. For applications requiring 18V or higher supply voltage, use FL7701MX (20V), LYT1403D-TL (308VAC), MP4050GS (265VAC), or LNK414LG (725V).

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