SC4539ULTRT LED Driver IC Equivalent & Substitute Parts

Part Overview

The SC4539ULTRT is a LED Driver IC manufactured by Semtech Corporation, designed as a 1-output DC-DC regulator with step-up (boost) topology and PWM dimming capability. This component delivers 30mA output current and operates across a 2.8V to 5.5V supply range, making it suitable for backlight applications. The part is classified as obsolete, necessitating identification of active equivalent and substitute components that maintain functional compatibility while offering continued availability and support.

Key Parameters

Parameter	SC4539ULTRT
Manufacturer	Semtech Corporation
Product Status	Obsolete
Type	DC DC Regulator
Topology	Step-Up (Boost)
Number of Outputs	1
Voltage - Supply (Min)	2.8V
Voltage - Supply (Max)	5.5V
Voltage - Output	5V ~ 22V
Current - Output / Channel	30mA
Frequency	800kHz
Dimming	PWM
Applications	Backlight
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	8-UFDFN Exposed Pad
RoHS Status	RoHS Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the SC4539ULTRT is determined by the following critical parameters:

Topology: Step-Up (Boost) DC-DC regulator with internal switch
Output Configuration: Single output, 1-channel LED driver
Supply Voltage Range: Minimum 2.7V to 5.5V maximum (SC4539ULTRT operates 2.8V minimum)
Output Voltage Capability: 5V to 22V range
Output Current: 30mA nominal (substitutes may exceed this rating)
Dimming Method: PWM control
Primary Application: Backlight LED driving
Operating Temperature: -40°C to 85°C
Package Type: Surface mount, compact form factor (8-pin or smaller)
Compliance: RoHS3 compliant, MSL 1

Substitute parts are grouped into two categories based on current handling capability and package density:

Category A - Direct Current Replacement (30mA to 40mA): Parts with output current ratings closest to the original 30mA specification, suitable for direct pin-compatible or footprint-compatible replacement.

Category B - Higher Current Capability (225mA and above): Parts with enhanced current handling that provide functional equivalence with additional design margin and flexibility for future application scaling.

Parameter Comparison

Parameter	SC4539ULTRT	BD6071HFN-TR	LT1932ES6#TRPBF	AP5725WUG-7	LT3465AES6#TRMPBF	LT3491EDC#TRPBF
Manufacturer	Semtech	Rohm	Analog Devices	Diodes Inc.	Analog Devices	Analog Devices
Product Status	Obsolete	Active	Active	Active	Active	Active
Topology	Step-Up (Boost)	Step-Up (Boost)	Step-Up (Boost)	Step-Up (Boost)	Step-Up (Boost)	Step-Up (Boost)
Number of Outputs	1	1	1	1	1	1
Voltage - Supply (Min)	2.8V	2.7V	1V	2.7V	2.7V	2.5V
Voltage - Supply (Max)	5.5V	5.5V	10V	5.5V	16V	12V
Voltage - Output	5V ~ 22V	14V	36V	26V	30V	27V
Current - Output / Channel	30mA	35mA	40mA	750mA (Switch)	225mA (Switch)	260mA (Switch)
Frequency	800kHz	1MHz	1.2MHz	1.2MHz	2.4MHz	2.3MHz
Dimming	PWM	PWM	PWM	PWM	PWM	PWM
Applications	Backlight	Backlight, Camera Flash	Backlight	Backlight	Backlight	Backlight
Operating Temperature	-40°C ~ 85°C (TA)	-30°C ~ 85°C (TA)	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)
Package / Case	8-UFDFN Exposed Pad	8-PowerUDFN	SOT-23-6 Thin	SOT-23-6 Thin	SOT-23-6 Thin	6-WFDFN Exposed Pad
RoHS Status	RoHS Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitutes (Closest Current Rating)

BD6071HFN-TR (Rohm Semiconductor) and LT1932ES6#TRPBF (Analog Devices) represent the most direct functional equivalents, with output current ratings of 35mA and 40mA respectively, closely matching the SC4539ULTRT 30mA specification. Both are active products with ROHS3 compliance and MSL 1 rating. BD6071HFN-TR operates within the identical supply voltage range (2.7V to 5.5V) and provides 14V output capability. LT1932ES6#TRPBF extends the supply range to 1V minimum and supports 36V output, offering greater design flexibility. Package considerations differ: BD6071HFN-TR uses 8-HSON form factor while LT1932ES6#TRPBF employs SOT-23-6 Thin packaging.

Secondary Substitutes (Enhanced Current Capability)

LT3465AES6#TRMPBF (Analog Devices) and LT3491EDC#TRPBF (Analog Devices) provide higher output current ratings of 225mA and 260mA respectively, enabling designs with increased power delivery margin. Both maintain PWM dimming, active product status, and ROHS3 compliance. LT3465AES6#TRMPBF supports extended supply voltage to 16V and 30V output. LT3491EDC#TRPBF operates within 2.5V to 12V supply range with 27V output capability. These parts are suitable when application requirements exceed 30mA or when design headroom is prioritized.

Alternative with Expanded Application Support

AP5725WUG-7 (Diodes Incorporated) delivers 750mA switch current with 26V output capability and 1.2MHz switching frequency. This part accommodates backlight applications requiring higher current delivery and is available in active status with ROHS3 compliance.

All recommended substitutes maintain RoHS3 compliance, MSL 1 rating, and -40°C to 85°C operating temperature range, ensuring regulatory and environmental compatibility with the original SC4539ULTRT specification.

Frequently Asked Questions (FAQ)

Q: Can BD6071HFN-TR directly replace SC4539ULTRT in existing designs?

A: BD6071HFN-TR provides functional equivalence in topology, dimming method, and output current rating (35mA vs. 30mA). However, package differences exist: BD6071HFN-TR uses 8-HSON while SC4539ULTRT uses 8-UFDFN. PCB layout modifications are required. Supply voltage compatibility is maintained (2.7V to 5.5V range). Verify output voltage requirement: BD6071HFN-TR provides 14V maximum versus SC4539ULTRT 22V maximum.

Q: What is the primary difference between Category A and Category B substitutes?

A: Category A substitutes (BD6071HFN-TR, LT1932ES6#TRPBF) maintain output current ratings within 35mA to 40mA, closely matching the original 30mA specification. Category B substitutes (LT3465AES6#TRMPBF, LT3491EDC#TRPBF) provide 225mA to 260mA output current, offering enhanced power delivery capability and design margin for applications requiring higher current or future scaling.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All recommended substitute parts carry ROHS3 compliance certification and MSL 1 (Unlimited) moisture sensitivity rating, matching the regulatory status of the original SC4539ULTRT.

Q: Which substitute offers the widest supply voltage range?

A: LT1932ES6#TRPBF supports the widest input range from 1V to 10V, compared to SC4539ULTRT 2.8V to 5.5V. This extended range provides flexibility for applications with variable supply conditions.

Q: What package options are available among substitutes?

A: Substitute parts employ three primary package types: 8-HSON (BD6071HFN-TR), SOT-23-6 Thin (AP5725WUG-7, LT1932ES6#TRPBF, LT3465AES6#TRMPBF), and 6-WFDFN Exposed Pad (LT3491EDC#TRPBF). Package selection impacts PCB footprint and thermal management characteristics.

Q: Can LT3465AES6#TRMPBF be used in applications originally designed for 30mA output?

A: Yes. LT3465AES6#TRMPBF with 225mA output current rating is suitable for applications designed for 30mA. The higher current capability provides design margin and does not create incompatibility. Output voltage (30V) exceeds SC4539ULTRT maximum (22V), requiring verification that application circuitry accommodates this specification.

Q: What is the operating temperature range for all substitutes?

A: All recommended substitutes operate across -40°C to 85°C (TA), matching the SC4539ULTRT specification. BD6071HFN-TR operates to -30°C minimum, providing slightly reduced low-temperature coverage.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message