RT8485GS LED Driver Controller - Equivalent & Substitute Parts

Part Overview

The RT8485GS is an active LED driver controller IC manufactured by Richtek USA Inc., designed for step-down (buck) and step-up (boost) topologies with analog and PWM dimming capabilities. This 14-SOP surface mount device operates across a 4.5V to 36V supply range and is commonly used in backlight and lighting applications. With 1180 pieces in stock and ROHS3 compliance, the RT8485GS remains an active product. Equivalent and substitute parts are identified for applications requiring alternative package formats, extended voltage ranges, automotive grading, or different frequency characteristics while maintaining core LED driver functionality.

Substiute Parts

RT8485GS

Richtek USA Inc.In Stock: 1205RT8485GS Datasheet

Current PartRFQ

LT8391AHUFD#PBF

Analog Devices Inc.In Stock: 856LT8391AHUFD#PBF Datasheet

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LT8391AIUFD#PBF

Analog Devices Inc.In Stock: 949LT8391AIUFD#PBF Datasheet

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TPS92640PWPT/NOPB

Texas InstrumentsIn Stock: 1841TPS92640PWPT/NOPB Datasheet

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TPS92692PWPR

Texas InstrumentsIn Stock: 1988TPS92692PWPR Datasheet

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TPS92692PWPT

Texas InstrumentsIn Stock: 89322TPS92692PWPT Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the RT8485GS are qualified based on the following core parameters that determine functional equivalence:

Primary Substitution Criteria:

• Type: DC DC Controller
• Topology: Step-Down (Buck), Step-Up (Boost) capability
• Number of Outputs: 1
• Dimming: Analog and PWM support
• Applications: Lighting-related use cases
• RoHS3 Compliance and active product status

Secondary Compatibility Factors:

• Voltage supply range overlap (minimum 4.5V input capability)
• Operating temperature range (-40°C minimum)
• Surface mount technology
• Frequency operation within LED driver control bands

The identified substitutes maintain the core LED driver controller functionality while offering variations in package format (28-QFN vs. 14-SOIC vs. 14/20-HTSSOP), maximum supply voltage ratings (36V to 85V), and automotive grading options. All substitutes are active products with ROHS3 compliance.

Parameter Comparison

Engineering Selection Recommendations

LT8391AHUFD#PBF and LT8391AIUFD#PBF (Analog Devices)

These parts are suitable substitutes for applications requiring extended maximum supply voltage (60V vs. 36V), higher frequency operation (600kHz ~ 2MHz), and automotive-grade qualification. Both feature 28-QFN packaging with exposed pad for improved thermal performance. The LT8391AHUFD#PBF supports operating temperatures to 150°C (TJ), while the LT8391AIUFD#PBF operates to 125°C (TJ). MSL rating of 1 (Unlimited) provides superior moisture handling compared to the RT8485GS. These are appropriate for automotive lighting and high-temperature backlight applications.

TPS92640PWPT/NOPB (Texas Instruments)

This substitute is limited to step-down (buck) topology only, making it suitable only for applications that do not require boost capability. It supports the highest maximum supply voltage (85V) and maintains 1MHz fixed frequency operation. Automotive grading and MSL rating of 1 (Unlimited) are provided. The 14-PowerTSSOP package maintains similar pin count to the RT8485GS. This part is appropriate for high-voltage buck-only LED driver applications.

TPS92692PWPR and TPS92692PWPT (Texas Instruments)

Both TPS92692 variants maintain buck and boost topology with supply range of 4.5V to 65V and frequency operation of 80kHz ~ 800kHz. The primary difference is packaging: PWPR is supplied in Cut Tape & Digi-Reel format, while PWPT is supplied in Tape & Reel format. The 20-PowerTSSOP package provides additional pins compared to the RT8485GS 14-SOIC. MSL rating of 2 (1 Year) and active product status support general lighting and signage applications. TPS92692PWPT has significantly higher inventory availability (89,288 pcs).

All substitutes maintain ROHS3 compliance and active product status, ensuring long-term availability and regulatory compliance.

Frequently Asked Questions (FAQ)

Q: Can the LT8391 series replace the RT8485GS in all applications?

A: The LT8391AHUFD#PBF and LT8391AIUFD#PBF maintain buck and boost topology, analog and PWM dimming, and single output configuration. However, the 28-QFN package differs from the 14-SOIC package of the RT8485GS, requiring PCB layout redesign. The extended voltage range (60V maximum) and higher frequency capability (600kHz ~ 2MHz) make these suitable for applications within the RT8485GS voltage range, but board-level integration changes are necessary.

Q: Is the TPS92640PWPT/NOPB a direct substitute?

A: The TPS92640PWPT/NOPB is not a direct substitute because it supports only step-down (buck) topology, whereas the RT8485GS supports both buck and boost. Use this part only if your application requires buck-only operation. The 14-PowerTSSOP package is similar in pin count to the 14-SOIC, but pinout verification is required.

Q: What are the key differences between TPS92692PWPR and TPS92692PWPT?

A: Both parts are electrically identical with identical specifications. The difference is packaging format: PWPR is supplied in Cut Tape & Digi-Reel format, while PWPT is supplied in Tape & Reel format. PWPT has significantly higher inventory availability (89,288 pcs vs. 1,967 pcs). Select based on your procurement and assembly requirements.

Q: Which substitute offers the best thermal performance?

A: The LT8391 series (both AHUFD and AIUFD variants) feature 28-QFN packages with exposed pad, providing superior thermal dissipation compared to the 14-SOIC package of the RT8485GS. The exposed pad design reduces junction temperature rise in high-power applications.

Q: Are all substitutes automotive-qualified?

A: The LT8391AHUFD#PBF, LT8391AIUFD#PBF, and TPS92640PWPT/NOPB carry automotive grading. The TPS92692PWPR and TPS92692PWPT do not have automotive grading. Select automotive-qualified parts for automotive lighting applications.

Q: What is the significance of MSL rating differences?

A: The RT8485GS has MSL rating of 3 (168 hours), meaning it must be used within 168 hours of moisture exposure. The LT8391 series and TPS92640 have MSL rating of 1 (Unlimited), providing superior moisture tolerance. The TPS92692 variants have MSL rating of 2 (1 Year). Higher MSL ratings reduce risk of moisture-related failures during storage and assembly.

Q: Can I use these substitutes interchangeably on the same PCB?

A: No. Each substitute has different package formats (14-SOIC, 28-QFN, 14-PowerTSSOP, or 20-PowerTSSOP) and pinout configurations. PCB redesign is required for each substitute. Verify pinout compatibility and thermal pad requirements before layout changes.

Q: Which substitute has the lowest frequency operation?

A: The TPS92692PWPR and TPS92692PWPT support the lowest minimum frequency at 80kHz, compared to 100kHz for the RT8485GS and 600kHz for the LT8391 series. Lower frequency operation may be beneficial for applications requiring reduced EMI or specific dimming characteristics.