FL7701M LED Driver IC - Equivalent & Substitute Parts

Part Overview

The FL7701M is an AC DC offline switcher LED driver IC manufactured by onsemi, designed for lighting applications with analog dimming capability. This device features a step-down (buck) topology with a single output and operates across a 9V to 20V supply range at frequencies between 20kHz and 250kHz. The FL7701M is classified as obsolete, making identification of functionally equivalent substitute parts essential for ongoing design support and production continuity.

Key Parameters

Parameter	FL7701M Specification
Manufacturer	onsemi
Product Status	Obsolete
Type	AC DC Offline Switcher
Topology	Step-Down (Buck)
Number of Outputs	1
Voltage Supply Range	9V to 20V
Frequency Range	20kHz to 250kHz
Dimming Type	Analog
Package	8-SOIC (0.154", 3.90mm Width)
Operating Temperature	-40°C to 125°C (TA)
Mounting Type	Surface Mount
Applications	Lighting

Substitute Part Grouping Explanation

Substitute parts for the FL7701M are categorized based on the following critical parameters that determine functional equivalence:

Primary Matching Criteria:

Type: AC DC Offline Switcher
Topology: Step-Down (Buck)
Number of Outputs: 1
Package: 8-SOIC form factor (preferred for direct PCB compatibility)
Operating Temperature Range: Minimum -40°C to 125°C
Applications: Lighting

Secondary Compatibility Factors:

Voltage Supply Range: 9V to 20V nominal operation
Frequency Range: 20kHz to 250kHz
Dimming Capability: Analog or compatible dimming method
Internal Switch Configuration: No internal switch preferred for topology match

Substitutes are presented in two categories: direct equivalents (FL7701MX) and similar alternatives that meet core functional requirements but may have variations in supply voltage range, dimming method, or package configuration.

Parameter Comparison

Parameter	FL7701M	FL7701MX	HV9921N8-G	LM3497MMX/NOPB	LYT1603D-TL	RT8402GJ6	TPS92001D
Manufacturer	onsemi	Fairchild Semiconductor	Microchip Technology	Texas Instruments	Power Integrations	Richtek USA Inc.	Texas Instruments
Product Status	Obsolete	Active	Active	Active	Active	Obsolete	Last Time Buy
Type	AC DC Offline Switcher	AC DC Offline Switcher	AC DC Offline Switcher	AC DC Offline Switcher	AC DC Offline Switcher	AC DC Offline Switcher	AC DC Offline Switcher
Topology	Step-Down (Buck)	Step-Down (Buck)	Step-Down (Buck)	Step-Down (Buck)	Step-Down (Buck)	Step-Down (Buck)	Flyback, Step-Down (Buck)
Number of Outputs	1	1	1	1	1	1	1
Voltage Supply (Min)	9V	9V	20V	8V	90VAC	10V	—
Voltage Supply (Max)	20V	20V	400V	12V	308VAC	30V	21V
Frequency	20kHz to 250kHz	20kHz to 250kHz	—	—	20kHz	—	100kHz
Dimming Type	Analog	Analog	Triac	Triac	—	Triac	Triac
Internal Switch	No	No	Yes	No	Yes	No	No
Package	8-SOIC	8-SOIC	SOT-89-3	10-VSSOP	8-SOIC	TSOT-23-6	8-SOIC
Operating Temperature	-40°C to 125°C (TA)	-40°C to 125°C (TA)	-40°C to 85°C (TA)	-40°C to 125°C (TJ)	-40°C to 125°C (TJ)	-40°C to 85°C (TA)	-40°C to 105°C (TJ)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	—	—	ROHS3 Compliant	ROHS3 Compliant	RoHS Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Direct Equivalent (Highest Compatibility):

FL7701MX is the primary substitute for FL7701M. Both devices share identical electrical specifications (9V to 20V supply, 20kHz to 250kHz frequency range, analog dimming), matching package format (8-SOIC), and operating temperature range (-40°C to 125°C). FL7701MX is currently in active production status, ensuring long-term availability and supply chain stability. This part requires no design modifications and provides pin-for-pin compatibility.

Active Production Alternatives:

HV9921N8-G (Microchip Technology) and LM3497MMX/NOPB (Texas Instruments) are functionally equivalent AC DC offline switcher buck topology devices suitable for lighting applications. Both are in active production. However, these alternatives feature triac dimming rather than analog dimming, requiring circuit design evaluation. HV9921N8-G operates at higher supply voltages (20V to 400V) and uses SOT-89-3 packaging, necessitating PCB layout modifications. LM3497MMX/NOPB operates at lower supply voltages (8V to 12V) and uses 10-VSSOP packaging, also requiring PCB redesign.

LYT1603D-TL (Power Integrations, LYTSwitch-1 series) is an active production AC DC offline switcher with step-down topology in 8-SOIC packaging. This device operates directly from AC mains (90VAC to 308VAC) with integrated internal switching, differing significantly from the FL7701M's DC supply requirement. Selection requires comprehensive circuit redesign.

Obsolete Status Alternatives:

RT8402GJ6 (Richtek USA Inc.) shares obsolete status with FL7701M and is not recommended for new designs. TPS92001D (Texas Instruments) is in last-time-buy status, limiting future availability.

Compliance Considerations:

FL7701MX, HV9921N8-G, LM3497MMX/NOPB, LYT1603D-TL, and RT8402GJ6 all carry REACH Unaffected status and EAR99 ECCN classification. RoHS compliance varies: HV9921N8-G, LM3497MMX/NOPB, RT8402GJ6, and TPS92001D are ROHS3 compliant; LYT1603D-TL is RoHS compliant. Moisture sensitivity levels are uniformly rated at MSL 1 (Unlimited) across all active alternatives, except RT8402GJ6 which is MSL 3 (168 Hours).

Frequently Asked Questions (FAQ)

Q: Can FL7701MX be used as a direct replacement for FL7701M without circuit modifications?

A: Yes. FL7701MX is a direct equivalent with identical electrical specifications, package format, and pin configuration. No circuit modifications are required for substitution.

Q: What is the primary difference between FL7701M and HV9921N8-G?

A: The FL7701M uses analog dimming control, while HV9921N8-G uses triac dimming. Additionally, HV9921N8-G operates at higher supply voltages (20V to 400V) compared to FL7701M (9V to 20V), and uses different packaging (SOT-89-3 versus 8-SOIC), requiring circuit redesign.

Q: Why is LYT1603D-TL listed as a substitute if it operates from AC mains?

A: LYT1603D-TL meets the core functional criteria of AC DC offline switcher with step-down topology and 8-SOIC packaging. However, its direct AC mains input (90VAC to 308VAC) differs fundamentally from FL7701M's DC supply requirement (9V to 20V), making it suitable only for applications where the input power architecture can be redesigned.

Q: Are there package compatibility concerns when selecting substitutes?

A: Yes. FL7701M uses 8-SOIC packaging. FL7701MX and LYT1603D-TL also use 8-SOIC, allowing direct PCB compatibility. HV9921N8-G (SOT-89-3), LM3497MMX/NOPB (10-VSSOP), and RT8402GJ6 (TSOT-23-6) require PCB layout modifications due to different pin counts and physical dimensions.

Q: What is the significance of product status when selecting a substitute?

A: FL7701M is obsolete, making substitution necessary. FL7701MX is in active production, ensuring long-term availability and supply continuity. HV9921N8-G, LM3497MMX/NOPB, and LYT1603D-TL are also active, supporting ongoing production. RT8402GJ6 is obsolete and TPS92001D is in last-time-buy status, both limiting future availability and not recommended for new designs.

Q: Does operating temperature range affect substitute selection?

A: FL7701M operates from -40°C to 125°C (TA). Most active substitutes maintain this range or exceed it. HV9921N8-G and RT8402GJ6 operate only to 85°C (TA), which may be insufficient for applications requiring the full -40°C to 125°C range. TPS92001D operates to 105°C (TJ), also below the FL7701M specification.

Q: What compliance certifications should be verified before substitution?

A: All listed substitutes carry REACH Unaffected status and EAR99 ECCN classification, matching FL7701M. RoHS compliance status varies. For applications requiring RoHS compliance, verify that the selected substitute meets the applicable RoHS directive version. Moisture sensitivity levels are MSL 1 (Unlimited) for most active parts, except RT8402GJ6 (MSL 3, 168 Hours), which requires controlled storage and handling.

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