RT8477GS LED Driver Controller - Equivalent & Substitute Parts

Part Overview

The RT8477GS is an LED driver controller IC manufactured by Richtek USA Inc., designed for backlight and lighting applications. It functions as a DC-DC controller supporting both step-down (buck) and step-up (boost) topologies with analog and PWM dimming capabilities. The part is currently discontinued at DiGi Electronics, making equivalent substitutes necessary for ongoing production and maintenance applications. With 4,570 units in stock and ROHS3 compliance, this 8-SOP packaged controller operates across a 4.5V to 50V supply range at 380kHz switching frequency.

Key Parameters

Parameter	RT8477GS Value
Manufacturer	Richtek USA Inc.
Package Type	8-SOIC (0.154", 3.90mm Width)
Product Status	Discontinued at DiGi Electronics
Type	DC DC Controller
Topology	Step-Down (Buck), Step-Up (Boost)
Number of Outputs	1
Voltage Supply (Min)	4.5V
Voltage Supply (Max)	50V
Voltage Output	50V
Switching Frequency	380kHz
Dimming Capability	Analog, PWM
Applications	Backlight, Lighting
Operating Temperature	-40°C ~ 85°C (TA)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	3 (168 Hours)

Substitute Part Grouping Explanation

Substitution eligibility for the RT8477GS is determined by the following critical parameters:

Primary Substitution Criteria:

DC-DC controller type with single output
Support for step-down (buck) and/or step-up (boost) topologies
Analog and PWM dimming capability
Supply voltage range compatibility (minimum 4.5V, maximum ≥50V)
Surface mount packaging suitable for PCB integration
ROHS3 compliance and automotive-grade availability where applicable

Secondary Compatibility Factors:

Operating temperature range (-40°C minimum required)
Switching frequency range (100kHz to 2MHz acceptable)
Package footprint compatibility or redesign feasibility
Moisture sensitivity level and storage requirements

The substitute parts listed below meet these criteria with varying package configurations and enhanced specifications. Parts are grouped by topology support and voltage rating compatibility.

Parameter Comparison

Parameter	RT8477GS	RT8462ZQW	HV9910CNG-G-M934	LT3755IUD#PBF	LT8391AHUFD#PBF	LT8391AIFE#TRPBF	LT8391EFE#TRPBF	LT8391IFE#PBF	MIC3203-1YM-TR	TPS92692PWPR
Manufacturer	Richtek	Richtek	Microchip	Analog Devices	Analog Devices	Analog Devices	Analog Devices	Analog Devices	Microchip	Texas Instruments
Package	8-SOIC	16-WQFN (3x3)	16-SOIC	16-QFN (3x3)	28-QFN (4x5)	28-TSSOP-EP	28-TSSOP-EP	28-TSSOP-EP	8-SOIC	20-HTSSOP
Topology	Buck, Boost	Buck, Boost	Buck	Flyback, SEPIC, Buck, Boost	Buck, Boost	Buck, Boost	Buck, Boost	Buck, Boost	Buck	Buck, Boost
Voltage Supply Min	4.5V	4.5V	15V	4.5V	4V	4V	4V	4V	4.5V	4.5V
Voltage Supply Max	50V	36V	450V	40V	60V	60V	60V	60V	42V	65V
Voltage Output	50V	—	—	—	60V	60V	60V	60V	—	—
Switching Frequency	380kHz	100kHz ~ 1MHz	25kHz, 100kHz	100kHz ~ 1MHz	600kHz ~ 2MHz	600kHz ~ 2MHz	150kHz ~ 650kHz	150kHz ~ 650kHz	1.5MHz	80kHz ~ 800kHz
Dimming	Analog, PWM	Analog, PWM	Analog, PWM	Analog, PWM	Analog, PWM	Analog, PWM	Analog, PWM	Analog, PWM	PWM	Analog, PWM
Operating Temperature	-40°C ~ 85°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 150°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C
RoHS Status	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3	ROHS3
Automotive Grade	—	—	—	—	Yes	Yes	Yes	Yes	—	—
MSL Rating	3	3	1	1	1	1	1	1	1	2

Engineering Selection Recommendations

Direct Package Compatibility (8-SOIC): MIC3203-1YM-TR maintains the same 8-SOIC package footprint as the RT8477GS. This part supports step-down (buck) topology with PWM dimming and operates across 4.5V to 42V supply range. It is active product status with ROHS3 compliance and MSL-1 rating, providing superior moisture handling compared to the original part.

Enhanced Voltage Range (Buck-Boost Topology): RT8462ZQW, LT8391AHUFD#PBF, LT8391AIFE#TRPBF, LT8391EFE#TRPBF, and LT8391IFE#PBF all support both buck and boost topologies with analog and PWM dimming. These parts offer extended operating temperature ranges (-40°C to 125°C or higher) and improved MSL ratings (1 vs. 3). The LT8391 series includes automotive-grade variants suitable for demanding applications.

High Voltage Applications (Buck Topology): HV9910CNG-G-M934 from Microchip supports supply voltages up to 450V, making it suitable for high-voltage LED driver applications. This part operates at 25kHz or 100kHz switching frequencies with analog and PWM dimming. MSL-1 rating and active product status ensure long-term availability.

Flexible Topology Support (Flyback, SEPIC, Buck, Boost): LT3755IUD#PBF from Analog Devices provides the broadest topology support including flyback and SEPIC configurations alongside buck and boost modes. Operating range of 4.5V to 40V with 100kHz to 1MHz frequency range and MSL-1 rating makes this suitable for diverse lighting applications.

Wide Input Voltage Range: TPS92692PWPR from Texas Instruments extends the maximum supply voltage to 65V while maintaining buck-boost topology support. The 20-HTSSOP package and 80kHz to 800kHz frequency range provide flexibility for various lighting and signage applications. MSL-2 rating requires standard moisture control during storage.

All substitute parts maintain ROHS3 compliance and are currently in active product status, ensuring long-term supply chain viability compared to the discontinued RT8477GS.

Frequently Asked Questions (FAQ)

Q: Can I directly replace RT8477GS with MIC3203-1YM-TR without PCB redesign? A: Yes. Both parts use 8-SOIC packaging with identical footprint dimensions (0.154" width, 3.90mm). However, MIC3203-1YM-TR supports only step-down (buck) topology, whereas RT8477GS supports both buck and boost. Verify your application requires only buck topology before substitution.

Q: What is the key difference between LT8391 variants (AHUFD, AIFE, EFE, IFE)? A: All LT8391 variants support identical buck-boost topology and voltage ranges (4V to 60V). Primary differences are package type (QFN vs. TSSOP), temperature rating (150°C for AHUFD vs. 125°C for others), and packaging format (tube vs. tape & reel). AHUFD and AIFE are automotive-grade; EFE and IFE are industrial-grade.

Q: Is HV9910CNG-G-M934 suitable for my 12V LED driver application? A: HV9910CNG-G-M934 has a minimum supply voltage of 15V, making it unsuitable for 12V applications. Use RT8462ZQW, LT3755IUD#PBF, LT8391 series, MIC3203-1YM-TR, or TPS92692PWPR instead, all of which support 4.5V minimum input.

Q: What does MSL rating mean for component storage? A: MSL (Moisture Sensitivity Level) indicates how long a component can be stored in standard conditions before moisture absorption requires baking. MSL-1 (unlimited) parts like LT8391 and LT3755 require no special storage. MSL-3 parts like RT8477GS require baking after 168 hours of exposure to ambient humidity.

Q: Can I use TPS92692PWPR as a direct substitute if my PCB layout uses 8-SOIC? A: No. TPS92692PWPR uses 20-HTSSOP packaging, which is significantly larger than 8-SOIC. PCB redesign is required. For same-footprint substitution, use MIC3203-1YM-TR.

Q: Which substitute part has the widest operating temperature range? A: LT8391AHUFD#PBF operates from -40°C to 150°C (junction temperature), providing the widest range. This automotive-grade variant is suitable for extreme temperature environments.

Q: Do all substitute parts support both analog and PWM dimming like RT8477GS? A: No. MIC3203-1YM-TR supports PWM dimming only. HV9910CNG-G-M934 supports both analog and PWM. All other substitutes (RT8462ZQW, LT3755IUD#PBF, LT8391 series, TPS92692PWPR) support both analog and PWM dimming.

Q: What is the maximum output voltage for each substitute? A: RT8477GS and LT8391 series support 50V to 60V output. RT8462ZQW, LT3755IUD#PBF, and TPS92692PWPR do not specify output voltage limits. HV9910CNG-G-M934 and MIC3203-1YM-TR also do not specify output voltage. Consult detailed datasheets for application-specific output voltage requirements.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message