FT8870-RT LED Driver IC Equivalent & Substitute Parts

Part Overview

The FT8870-RT is an AC DC offline switcher LED driver IC manufactured by Fremont Micro Devices Ltd, designed for single-output backlight applications using step-down (buck) topology. This device operates at 5kHz with a maximum supply voltage of 7V and is packaged in 8-SOP surface mount configuration.

The FT8870-RT is classified as obsolete. Due to its discontinued status, identifying functionally equivalent substitute parts is essential for design continuity, production planning, and long-term component sourcing strategy. Active alternatives with comparable electrical and mechanical specifications are available from multiple manufacturers.

Substiute Parts

FT8870-RT

Fremont Micro Devices LtdIn Stock: 780FT8870-RT Datasheet

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AL1692L-30BS7-13

Diodes IncorporatedIn Stock: 871AL1692L-30BS7-13 Datasheet

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AP1685MTR-G1

Diodes IncorporatedIn Stock: 40399AP1685MTR-G1 Datasheet

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HV9801ALG-G

Microchip TechnologyIn Stock: 1150HV9801ALG-G Datasheet

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LNK404LG

Power IntegrationsIn Stock: 1455LNK404LG Datasheet

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MP4068GS

Monolithic Power SystemsIn Stock: 966MP4068GS Datasheet

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RT8497AGS

Richtek USA Inc.In Stock: 25338RT8497AGS Datasheet

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TPS92315DBVT

Texas InstrumentsIn Stock: 1646TPS92315DBVT Datasheet

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TS19451CY RMG

Taiwan Semiconductor CorporationIn Stock: 1065TS19451CY RMG Datasheet

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TS19452CS RLG

Taiwan Semiconductor CorporationIn Stock: 900TS19452CS RLG Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the FT8870-RT is determined by the following critical parameters:

Primary Matching Criteria:

• Device Type: AC DC Offline Switcher
• Topology: Step-Down (Buck)
• Number of Outputs: 1
• Mounting Type: Surface Mount
• Package compatibility: 8-SOIC or equivalent 8-pin surface mount packages

Secondary Compatibility Factors:

• Operating temperature range overlap with -40°C minimum
• Supply voltage range that accommodates the 7V maximum specification
• Internal switch configuration (preferred: No, for direct functional equivalence)
• Regulatory compliance: REACH Unaffected, EAR99 classification

Substitute parts are grouped into two categories based on topology alignment:

Category A - Direct Buck Topology Substitutes: Parts maintaining step-down (buck) topology with no internal switch, providing closest functional equivalence.

Category B - Alternative Topology Substitutes: Parts using flyback or multi-topology configurations with internal switches, suitable for applications where topology flexibility is acceptable and pin compatibility can be verified.

Parameter Comparison

Engineering Selection Recommendations

For Direct Functional Replacement (Preferred):

HV9801ALG-G from Microchip Technology is the most suitable direct substitute. It maintains step-down (buck) topology without internal switch, matching the FT8870-RT's core architecture. Operating temperature range (-40°C to 125°C) aligns with the original specification. The device is active status with ROHS3 compliance and REACH Unaffected certification. Package compatibility is confirmed as 8-SOIC. Supply voltage range (15V to 450V) exceeds the FT8870-RT's 7V maximum, providing design margin.

For Cost-Optimized Alternatives:

AP1685MTR-G1 (Diodes Incorporated) and TS19452CS RLG (Taiwan Semiconductor Corporation) offer active status with ROHS3 compliance. Both use step-down (buck) topology in 8-pin surface mount packages. AP1685MTR-G1 supports higher supply voltage (25V maximum) and higher output current (2.5A). TS19452CS RLG accommodates significantly higher supply voltage (400V maximum) with lower output current (100mA), suitable for different application requirements.

For Legacy System Continuity:

RT8497AGS (Richtek USA Inc.) maintains 8-SOP packaging identical to FT8870-RT and step-down (buck) topology. Although classified as obsolete, it provides pin-compatible migration path. ROHS3 compliance and REACH Unaffected status confirm regulatory alignment.

Regulatory and Compliance Considerations:

All recommended substitutes carry REACH Unaffected and EAR99 ECCN classifications, matching the original part's regulatory profile. ROHS3 compliance is standard across active alternatives, ensuring environmental and safety standard adherence.

Frequently Asked Questions (FAQ)

Q: Can HV9801ALG-G directly replace FT8870-RT without circuit modification?

A: HV9801ALG-G shares the same AC DC offline switcher type, step-down (buck) topology, and 8-SOIC package footprint. However, pin-level compatibility must be verified against the original schematic. Supply voltage range (15V to 450V) differs from FT8870-RT (7V maximum), requiring circuit validation to ensure proper operation within your application's voltage envelope.

Q: What is the primary difference between step-down (buck) and flyback topologies in LED driver substitution?

A: Step-down (buck) topology directly reduces input voltage to output voltage with continuous current flow, used in the FT8870-RT. Flyback topology uses energy storage in a transformer, enabling galvanic isolation and multiple output configurations. Substituting flyback devices (such as TPS92315DBVT or LNK404LG) requires circuit redesign and is not recommended for direct pin-for-pin replacement.

Q: Why is internal switch configuration important for substitution?

A: The FT8870-RT lacks an internal switch, requiring external switching components in the application circuit. Substitutes with internal switches (such as AP1685MTR-G1 or TS19452CS RLG) integrate switching functionality, potentially simplifying circuit design but requiring verification of pin assignments and control signal compatibility.

Q: Are all substitute parts available in the same 8-SOP package?

A: Most substitutes use 8-pin surface mount packages (8-SOIC or 8-SOP), ensuring PCB footprint compatibility. LNK404LG uses eSIP-7F package (7-pin through-hole), requiring PCB redesign. TPS92315DBVT uses SOT-23-6 package (6-pin), incompatible with 8-pin footprints. Package verification is mandatory before component selection.

Q: What is the significance of MSL (Moisture Sensitivity Level) in component substitution?

A: MSL rating indicates moisture absorption limits during storage and handling. FT8870-RT carries MSL 3 (168 hours maximum exposure). Substitutes with MSL 1 (unlimited) or MSL 2 (1 year) offer superior moisture tolerance, reducing risk of solder joint failures during assembly. Lower MSL ratings provide manufacturing flexibility without requiring extended baking procedures.

Q: Can I use TS19451CY RMG or TS19452CS RLG for backlight applications?

A: TS19452CS RLG is specified for lighting applications and supports backlight use cases. TS19451CY RMG explicitly lists backlight and lighting applications. Both devices operate at 50mA and 100mA output current respectively, suitable for LED backlight circuits. Supply voltage range (20V to 400V) accommodates typical backlight power requirements.

Q: What compliance certifications should I verify before finalizing a substitute part?

A: Confirm REACH Unaffected status and EAR99 ECCN classification to match the original FT8870-RT. Verify RoHS compliance level (RoHS3 Compliant or RoHS Compliant) for your target market. Cross-reference MSL rating against your manufacturing process requirements. Validate operating temperature range (-40°C minimum preferred) against your application's thermal environment.