FAN5331SX LED Driver IC Equivalent & Substitute Parts

Part Overview

The FAN5331SX is an LED Driver IC manufactured by onsemi, designed as a 1-output DC-DC Step-Up (Boost) regulator with 1A switch capability in SOT-23-5 packaging. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. The FAN5331SX operates across a 2.7V to 5.5V supply range with 20V output capability, delivering 1.65MHz switching frequency for backlight applications.

Key Parameters

Parameter	FAN5331SX Value
Manufacturer	onsemi
Product Status	Obsolete
Type	DC DC Regulator
Topology	Step-Up (Boost)
Number of Outputs	1
Voltage - Supply (Min)	2.7V
Voltage - Supply (Max)	5.5V
Voltage - Output	20V
Current - Output / Channel	1A (Switch)
Frequency	1.65MHz
Package / Case	SOT-23-5
Operating Temperature	-40°C ~ 85°C (TA)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the FAN5331SX is determined by the following critical parameters:

Primary Substitution Criteria:

Topology: Step-Up (Boost) configuration
Number of Outputs: Single output
Supply Voltage Range: Minimum 2.7V input capability
Output Voltage: 20V or higher capability
Current Rating: 1A or greater switch current
Package Type: Surface mount with compatible pinout
Operating Temperature: -40°C minimum to 85°C or higher
RoHS Compliance: ROHS3 Compliant

Secondary Compatibility Factors:

Switching Frequency: 1.2MHz to 2MHz range acceptable
Dimming Capability: Analog, PWM, or no dimming support
Internal Switch: Required
Mounting Type: Surface Mount

Substitutes are grouped into two categories: direct topology matches (Step-Up/Boost) and alternative topology solutions (Step-Down/Buck) where application requirements permit topology change.

Parameter Comparison

Part Number	Manufacturer	Topology	Supply Min (V)	Supply Max (V)	Output (V)	Current (A)	Frequency (MHz)	Package	Status	Temp Range (°C)
FAN5331SX	onsemi	Step-Up (Boost)	2.7	5.5	20	1	1.65	SOT-23-5	Obsolete	-40 ~ 85
AP5726WUG-7	Diodes Incorporated	Step-Up (Boost)	2.7	5.5	—	0.75	1.2	TSOT-23-6	Active	-40 ~ 85
MCP1643-I/MC	Microchip Technology	Step-Up (Boost)	0.5	5	5	0.55	1	8-DFN (2x3)	Active	-40 ~ 85
MIC2291YD5-TR	Microchip Technology	Step-Up (Boost)	2.5	10	—	1.2	1.2	TSOT-23-5	Active	-40 ~ 125
MIC2293-15YML-TR	Microchip Technology	Step-Up (Boost)	2.5	10	—	0.75	2	8-MLF® (2x2)	Active	-40 ~ 125
MIC3287YD5-TR	Microchip Technology	Step-Up (Boost)	2.8	6.5	36	0.35	1.2	TSOT-23-5	Active	-40 ~ 125
MP2410AGJ-P	Monolithic Power Systems Inc.	Step-Down (Buck)	4.2	24	—	2	1	TSOT-23-6	Active	-40 ~ 125
MP2480DN-LF-Z	Monolithic Power Systems Inc.	Step-Down (Buck)	5	36	—	3	2	8-SOIC-EP	Active	-40 ~ 85
MPQ2489DQ-LF-P	Monolithic Power Systems Inc.	Step-Down (Buck)	6	55	—	0.55	0.6	6-QFN (3x3)	Active	-40 ~ 125
PAM2804AAB010	Diodes Incorporated	Step-Down (Buck)	2.5	6	—	1	1.5	TSOT-23-5	Active	-40 ~ 85
TPS61178RNWR	Texas Instruments	Step-Up (Boost)	2.7	20	4.5 ~ 20	10	0.2 ~ 2.2	13-VQFN	Active	-40 ~ 125

Engineering Selection Recommendations

Direct Topology Substitutes (Step-Up/Boost):

The following parts maintain Step-Up (Boost) topology and are recommended for applications requiring voltage step-up conversion:

MIC2291YD5-TR: Active status, TSOT-23-5 package matches FAN5331SX footprint, 1.2A switch current exceeds original 1A specification, extended temperature range to 125°C, ROHS3 compliant. Supply range 2.5V to 10V accommodates FAN5331SX 2.7V to 5.5V requirement.
TPS61178RNWR: Active status, highest current capability at 10A switch current, adjustable output 4.5V to 20V matches FAN5331SX 20V output, extended temperature range to 125°C, ROHS3 compliant. Larger 13-VQFN package requires PCB layout modification.
AP5726WUG-7: Active status, TSOT-23-6 package, 750mA switch current is lower than FAN5331SX 1A specification, suitable for reduced current applications, ROHS3 compliant, matching temperature range -40°C to 85°C.
MIC2293-15YML-TR: Active status, 750mA switch current, extended temperature range to 125°C, 8-MLF package, ROHS3 compliant. Requires PCB layout redesign due to different package footprint.
MIC3287YD5-TR: Active status, TSOT-23-5 package matches FAN5331SX footprint, 36V output capability exceeds 20V requirement, extended temperature range to 125°C, ROHS3 compliant. Lower 350mA current suitable for reduced power applications.

Alternative Topology Substitutes (Step-Down/Buck):

The following parts employ Step-Down (Buck) topology and are applicable only where input voltage exceeds output voltage requirement:

PAM2804AAB010: Active status, TSOT-23-5 package matches FAN5331SX footprint, 1A current matches original specification, 2.5V to 6V supply range, matching temperature range -40°C to 85°C, ROHS3 compliant. Topology change requires application redesign.
MP2410AGJ-P: Active status, 2A current exceeds original specification, extended temperature range to 125°C, ROHS3 compliant. TSOT-23-6 package requires footprint modification. Minimum 4.2V supply exceeds FAN5331SX 2.7V capability.
MP2480DN-LF-Z: Active status, 3A current capability, 5V to 36V supply range, matching temperature range -40°C to 85°C, ROHS3 compliant. 8-SOIC-EP package requires significant PCB redesign.
MPQ2489DQ-LF-P: Active status, AEC-Q100 automotive qualification, extended temperature range to 125°C, ROHS3 compliant. 550mA current and 6V minimum supply limit applicability. 6-QFN package requires footprint modification.

Compliance Status:

All substitute parts maintain ROHS3 compliance and unlimited moisture sensitivity level (MSL 1) matching the original FAN5331SX specification. All parts are REACH unaffected and classified under ECCN EAR99.

Frequently Asked Questions (FAQ)

Q: Can MIC2291YD5-TR directly replace FAN5331SX without PCB modification?

A: Yes. MIC2291YD5-TR uses identical TSOT-23-5 package footprint as FAN5331SX. Pin configuration compatibility requires verification against respective datasheets. Supply voltage range 2.5V to 10V encompasses FAN5331SX 2.7V to 5.5V requirement. Switch current 1.2A exceeds 1A specification, providing design margin.

Q: Why are Step-Down (Buck) topology parts listed as substitutes for a Step-Up (Boost) regulator?

A: Step-Down topology substitutes apply only to applications where input voltage exceeds desired output voltage. These parts cannot replace Step-Up functionality in applications requiring voltage multiplication from low input sources. Topology selection depends on specific application input and output voltage requirements.

Q: What is the impact of package change from SOT-23-5 to alternative packages?

A: Package changes require PCB layout redesign, including trace routing, component placement, and thermal management modifications. Larger packages such as 8-SOIC-EP or 13-VQFN may provide improved thermal performance but demand increased board space. Smaller packages maintain footprint compatibility but may limit thermal dissipation capability.

Q: Does MIC3287YD5-TR 36V output capability create compatibility issues?

A: No. Higher output voltage capability does not create compatibility issues. Output voltage is set by external feedback network components. MIC3287YD5-TR can be configured for 20V output matching FAN5331SX specification through appropriate resistor divider selection.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance matching FAN5331SX specification. Moisture sensitivity level remains MSL 1 (unlimited) across all alternatives, eliminating moisture handling requirement changes.

Q: Which substitute provides best thermal performance for high-current applications?

A: TPS61178RNWR provides highest current capability at 10A switch current with 13-VQFN package offering improved thermal characteristics. MP2480DN-LF-Z Step-Down alternative provides 3A capability in 8-SOIC-EP package with exposed pad for thermal management. Package selection depends on application thermal requirements and available board space.

Q: Can PAM2804AAB010 operate at FAN5331SX minimum supply voltage of 2.7V?

A: No. PAM2804AAB010 minimum supply voltage is 2.5V, which is below FAN5331SX 2.7V specification. However, 2.5V minimum provides operational margin below FAN5331SX requirement. Verify application minimum supply voltage against PAM2804AAB010 datasheet specifications before selection.

Q: What dimming capability differences exist between FAN5331SX and substitutes?

A: FAN5331SX provides no dimming capability. MIC2291YD5-TR and MIC2293-15YML-TR offer Analog and PWM dimming options. AP5726WUG-7 provides PWM dimming. If dimming functionality is not required, dimming capability presence does not affect substitution suitability. If dimming is required, select parts with appropriate dimming support.

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