LM3520SD/NOPB LED Driver IC Equivalent & Substitute Parts

Part Overview

The LM3520SD/NOPB is a LED Driver IC manufactured by Texas Instruments, classified as a Power Management (PMIC) component. This device functions as a 2-output DC DC regulator with step-up (boost) topology, featuring PWM dimming capability and an internal switch rated for 700mA. The part is designed for backlight applications and operates across a supply voltage range of 2.7V to 5.5V, delivering output voltage of 22.5V to 23.2V at a switching frequency of 1.1MHz.

The LM3520SD/NOPB is currently listed as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure component availability, and support ongoing production requirements for systems utilizing this LED driver topology.

Substiute Parts

LM3520SD/NOPB

Texas InstrumentsIn Stock: 863LM3520SD/NOPB Datasheet

Current PartRFQ

A8518KLPTR-T

Allegro MicroSystemsIn Stock: 18832A8518KLPTR-T Datasheet

MFR RecommendedRFQ

ISL97682IRTZ-T

Renesas Electronics CorporationIn Stock: 1145ISL97682IRTZ-T Datasheet

MFR RecommendedRFQ

ISL97682IRTZR5509

Renesas Electronics CorporationIn Stock: 1014ISL97682IRTZR5509 Datasheet

MFR RecommendedRFQ

LT3466EDD#PBF

Analog Devices Inc.In Stock: 3046LT3466EDD#PBF Datasheet

MFR RecommendedRFQ

LT3466EDD-1#PBF

Analog Devices Inc.In Stock: 2941LT3466EDD-1#PBF Datasheet

MFR RecommendedRFQ

LT3486EDHC#PBF

Analog Devices Inc.In Stock: 3125LT3486EDHC#PBF Datasheet

MFR RecommendedRFQ

LT3486EDHC#TRPBF

Analog Devices Inc.In Stock: 2298LT3486EDHC#TRPBF Datasheet

MFR RecommendedRFQ

LT3486IFE#PBF

Analog Devices Inc.In Stock: 9416LT3486IFE#PBF Datasheet

MFR RecommendedRFQ

LT3909IMSE#PBF

Analog Devices Inc.In Stock: 1651LT3909IMSE#PBF Datasheet

MFR RecommendedRFQ

LT3909IMSE#TRPBF

Analog Devices Inc.In Stock: 947LT3909IMSE#TRPBF Datasheet

MFR RecommendedRFQ

MP3312GC-Z

Monolithic Power Systems Inc.In Stock: 141095MP3312GC-Z Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the LM3520SD/NOPB are selected based on functional equivalence within the LED driver IC category. The primary substitution criteria are:

Core Functional Parameters:

• Topology: Step-Up (Boost) DC DC Regulator
• Number of Outputs: 2
• Dimming Capability: PWM support
• Internal Switch: Present
• Application: Backlight

Electrical Compatibility Parameters:

• Supply voltage range must encompass or closely align with 2.7V to 5.5V
• Output voltage capability must support the 22.5V to 23.2V range or higher
• Current output per channel must meet or exceed 700mA requirements
• Switching frequency in the range of 600kHz to 2.2MHz

Physical & Compliance Parameters:

• Surface mount packaging
• RoHS3 compliance
• Operating temperature range of -40°C to 85°C or wider

Substitute parts are grouped into two categories: direct functional equivalents with active product status, and alternative topologies that maintain core LED driver functionality while offering enhanced specifications or different packaging options.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes (Active Status, Closest Functional Match):

LT3486IFE#PBF and LT3486EDHC#TRPBF are the most suitable direct substitutes for the LM3520SD/NOPB. Both are manufactured by Analog Devices Inc. and maintain active product status. The LT3486 series provides 1.3A switch current capability, exceeding the 700mA requirement of the original part. Supply voltage range extends from 2.5V to 24V, encompassing the LM3520 operating window. These parts support PWM dimming for backlight applications and are RoHS3 compliant with MSL 1 rating. The LT3486IFE#PBF variant operates to 125°C junction temperature, providing enhanced thermal performance. Package options include 16-TSSOP-EP, which differs from the original 14-WFDFN but maintains surface mount compatibility.

Secondary Substitutes (Active Status, Extended Capability):

LT3466EDD#PBF and LT3466EDD-1#PBF, both from Analog Devices Inc., offer 400mA output current with supply voltage range of 2.7V to 24V. These parts maintain the 2.7V minimum supply voltage of the original design and deliver 39.5V output voltage. Operating frequency of 1MHz aligns closely with the LM3520 specification. Both variants are RoHS3 compliant with MSL 1 rating and support PWM dimming for backlight applications.

ISL97682IRTZ-T and ISL97682IRTZR5509, manufactured by Renesas Electronics Corporation, provide active product status with PWM dimming capability. These parts deliver 45V output voltage and operate at 600kHz switching frequency. Supply voltage range of 4V to 26.5V encompasses the LM3520 operating window. Current output per channel is rated at 100mA, which is lower than the original 700mA specification and may require design evaluation for current-limited applications.

Alternative Substitutes (Extended Specifications):

LT3909IMSE#PBF and LT3909IMSE#TRPBF, from Analog Devices Inc., support both analog and PWM dimming with 50mA output current. Supply voltage range extends to 40V maximum, and these parts are qualified to automotive grade (AEC-Q100) with operating temperature to 125°C. These alternatives are suitable for applications requiring extended voltage range and automotive qualification.

A8518KLPTR-T, manufactured by Allegro MicroSystems, provides automotive-grade qualification (AEC-Q100) with 200mA output current and 40V output voltage capability. Supply voltage range of 4.5V to 40V and operating temperature to 125°C support extended environmental specifications. This part supports both analog and PWM dimming modes.

Compliance & Availability:

All substitute parts listed maintain RoHS3 compliance and REACH unaffected status, consistent with the original LM3520SD/NOPB. Inventory availability ranges from 899 to 9400 pieces across the substitute options, ensuring supply continuity. Moisture sensitivity levels vary from MSL 1 (unlimited) to MSL 3 (168 hours), requiring consideration of storage and handling procedures during component procurement and assembly.

Frequently Asked Questions (FAQ)

Q: Can the ISL97682IRTZ-T directly replace the LM3520SD/NOPB in existing designs?

A: The ISL97682IRTZ-T maintains the same 2-output boost topology and PWM dimming capability as the LM3520SD/NOPB. However, the output current per channel is rated at 100mA compared to the original 700mA specification. This part is suitable only for applications where the 100mA current limit is acceptable. Additionally, the package differs (16-WFQFN versus 14-WFDFN), requiring PCB layout modifications. Supply voltage range of 4V to 26.5V encompasses the original 2.7V to 5.5V window, though the 4V minimum is higher than the original 2.7V minimum.

Q: What are the key differences between LT3486IFE#PBF and LT3486EDHC#TRPBF?

A: Both parts are functionally identical in electrical specifications, with identical supply voltage range (2.5V to 24V), output current (1.3A switch), and switching frequency (2.2MHz). The primary difference is packaging: LT3486IFE#PBF is supplied in tube packaging, while LT3486EDHC#TRPBF is supplied in tape and reel format. The tape and reel variant is typically preferred for automated assembly processes. Both support PWM dimming and are RoHS3 compliant with MSL 1 rating.

Q: Why do some substitute parts have lower output current ratings than the LM3520SD/NOPB?

A: The ISL97682 series (100mA per channel) and LT3909 series (50mA per channel) are designed for lower-power backlight applications. These parts are suitable for designs where the LED driver current requirement is lower than the original 700mA specification. For applications requiring the full 700mA capability, the LT3486 series (1.3A) or LT3466 series (400mA) are more appropriate selections.

Q: Are all substitute parts automotive qualified?

A: Not all substitutes carry automotive qualification. LT3909IMSE#PBF, LT3909IMSE#TRPBF, and A8518KLPTR-T are qualified to AEC-Q100 automotive grade. The remaining substitutes (ISL97682 series, LT3486 series, LT3466 series) do not carry automotive qualification. Automotive-qualified parts are required only for applications subject to automotive reliability and environmental standards.

Q: What is the significance of MSL (Moisture Sensitivity Level) differences?

A: MSL ratings indicate the maximum time a component can be stored in ambient conditions before requiring baking prior to reflow soldering. LM3520SD/NOPB, LT3486 series, and LT3466 series carry MSL 1 (unlimited storage). ISL97682 series carries MSL 3 (168 hours maximum), requiring baking if storage exceeds 168 hours. A8518KLPTR-T carries MSL 2 (1 year). For high-volume production with extended component storage, MSL 1 rated parts minimize handling complexity.

Q: Can the LT3486IFE#PBF be used in designs originally specified for 22.5V to 23.2V output voltage?

A: The LT3486IFE#PBF does not specify a fixed output voltage rating in the provided data. Output voltage is typically set by external resistor networks in boost converter designs. The part supports the boost topology and PWM dimming required for LED driver applications. Design verification is necessary to confirm that external component selection can achieve the required 22.5V to 23.2V output voltage range with the LT3486 topology.

Q: What packaging considerations apply when substituting the 14-WFDFN original part?

A: The LM3520SD/NOPB uses 14-WFDFN packaging. Most substitute parts use alternative packages: ISL97682 series use 16-WFQFN, LT3486 series use 16-TSSOP or 16-DFN, LT3466 series use 10-DFN, LT3909 series use 12-TSSOP, and A8518 uses 16-TSSOP. All are surface mount packages with exposed pads. PCB layout modifications are required for any package change, including trace routing, thermal via placement, and component footprint updates.