LM3557SD-2/NOPB Equivalent & Substitute Parts

Part Overview

The LM3557SD-2/NOPB is an LED Driver IC manufactured by Texas Instruments, classified as a Power Management (PMIC) component. This device functions as a DC DC Regulator with Step-Up (Boost) topology, delivering 800mA switch current output for backlight applications. The part operates across a 2.7V to 7.5V supply voltage range at 1.2MHz switching frequency with an 8-WSON (3x3) package footprint.

The LM3557SD-2/NOPB carries an Obsolete part status. Locating equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements. Substitute parts must maintain functional compatibility within the LED driver category while meeting the electrical and mechanical constraints of the original design.

Key Parameters

Parameter	LM3557SD-2/NOPB
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Type	DC DC Regulator
Topology	Step-Up (Boost)
Number of Outputs	1
Voltage - Supply (Min)	2.7V
Voltage - Supply (Max)	7.5V
Current - Output / Channel	800mA (Switch)
Frequency	1.2MHz
Operating Temperature	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount
Package / Case	8-WFDFN Exposed Pad
Supplier Device Package	8-WSON (3x3)
Applications	Backlight
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Part Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the LM3557SD-2/NOPB are selected based on strict alignment with the following critical parameters:

Primary Substitution Criteria:

Topology: Step-Up (Boost) DC DC Regulator
Application: Backlight LED driver
Number of Outputs: 1
Supply Voltage Range: Minimum 2.7V input capability
Operating Temperature: -40°C to 85°C or higher
RoHS3 Compliance
Surface Mount technology

Secondary Compatibility Factors:

Current Output Capability: 800mA or greater
Switching Frequency: Proximity to 1.2MHz (range 600kHz to 2MHz acceptable)
Package Type: Surface Mount (various packages acceptable)
Internal Switch: Required

Substitute parts are grouped into two categories based on functional alignment:

Category A - Direct Functional Equivalents (Backlight-Optimized): Parts with Step-Up (Boost) topology, backlight application focus, and current output ratings between 700mA and 1.5A. These include TPS61161ADRVR, TPS61161DRVR, AP3031KTR-G1, LT1937ESC6#TRPBF, and MIC2293-34YML-TR.

Category B - Extended Capability Substitutes (Higher Current/Voltage): Parts with Step-Up (Boost) topology, backlight or lighting applications, and current output ratings exceeding 1.4A. These include LTC3454EDD#PBF, MAX8607ETD+T, MIC2299-15YML-TR, and MIC3223YTSE-TR.

Category C - Specialized Topology (Switched Capacitor): LTC3201EMS#PBF operates on Switched Capacitor (Charge Pump) topology with lower current output (100mA), suitable only for applications with reduced current requirements.

Parameter Comparison

Part Number	Manufacturer	Topology	Supply Min (V)	Supply Max (V)	Current Output (mA)	Frequency (MHz)	Package	Status	Temp Range (°C)
LM3557SD-2/NOPB	Texas Instruments	Step-Up (Boost)	2.7	7.5	800	1.2	8-WSON (3x3)	Obsolete	-40 to 85
TPS61161ADRVR	Texas Instruments	Step-Up (Boost)	2.7	18	700	0.6	6-WSON (2x2)	Active	-40 to 85
TPS61161DRVR	Texas Instruments	Step-Up (Boost)	2.7	18	700	0.6	6-WSON (2x2)	Active	-40 to 85
AP3031KTR-G1	Diodes Incorporated	Step-Up (Boost)	2.7	16	1400	1.0	TSOT-23-6	Active	-40 to 85
LT1937ESC6#TRPBF	Analog Devices Inc.	Step-Up (Boost)	2.5	10	320	1.2	SC-70-6	Active	-40 to 85
LTC3201EMS#PBF	Analog Devices Inc.	Switched Capacitor (Charge Pump)	2.7	4.5	100	1.8	10-MSOP	Active	-40 to 85
LTC3454EDD#PBF	Analog Devices Inc.	Step-Down (Buck), Step-Up (Boost)	2.7	5.5	1000	1.0	10-DFN (3x3)	Active	-40 to 85
MAX8607ETD+T	Analog Devices Inc./Maxim Integrated	Step-Up (Boost)	2.7	5.5	1500	1.0	14-TDFN (3x3)	Active	-40 to 85
MIC2293-34YML-TR	Microchip Technology	Step-Up (Boost)	2.5	10	750	2.0	8-MLF® (2x2)	Active	-40 to 125
MIC2299-15YML-TR	Microchip Technology	Step-Up (Boost)	2.5	10	3500	2.0	12-MLF™ (3x3)	Active	-40 to 125
MIC3223YTSE-TR	Microchip Technology	Step-Up (Boost)	4.5	20	3500	1.0	16-TSSOP-EP	Active	-40 to 125

Engineering Selection Recommendations

For Direct Replacement in Backlight Applications:

TPS61161ADRVR and TPS61161DRVR are Active status parts from Texas Instruments with identical electrical specifications. Both maintain the 2.7V minimum supply voltage, operate within the -40°C to 85°C temperature range, and are ROHS3 compliant. The primary trade-off is reduced current output (700mA versus 800mA) and smaller package footprint (6-WSON 2x2 versus 8-WSON 3x3). These parts are suitable for applications where the 700mA output meets design requirements.

AP3031KTR-G1 from Diodes Incorporated provides higher current capability (1.4A) in a compact TSOT-23-6 package. This part maintains 2.7V minimum supply voltage and -40°C to 85°C operating range with ROHS3 compliance. The increased current capacity accommodates higher brightness LED configurations.

MIC2293-34YML-TR from Microchip Technology delivers 750mA output current in an 8-MLF® (2x2) package with extended temperature range (-40°C to 125°C). This part supports 2.5V minimum supply voltage and maintains ROHS3 compliance. The higher operating temperature ceiling provides thermal margin for demanding applications.

For Applications Requiring Extended Supply Voltage Range:

TPS61161ADRVR and TPS61161DRVR support supply voltages up to 18V, compared to the original 7.5V maximum. This extended range accommodates higher input voltage sources without additional conditioning.

For Applications Requiring Higher Current Output:

MAX8607ETD+T provides 1.5A flash current capability with Step-Up (Boost) topology, suitable for high-brightness LED applications. Supply voltage range is 2.7V to 5.5V with ROHS3 compliance and -40°C to 85°C operation.

LTC3454EDD#PBF combines Step-Down (Buck) and Step-Up (Boost) topologies in a single device, delivering 1A output current. This dual-topology approach provides flexibility for applications requiring both voltage regulation directions.

MIC2299-15YML-TR and MIC3223YTSE-TR deliver 3.5A switch current for high-power LED lighting and signage applications. Both maintain ROHS3 compliance with extended temperature ranges (-40°C to 125°C).

For Low-Current Applications:

LTC3201EMS#PBF operates on Switched Capacitor (Charge Pump) topology with 100mA output current. This part is suitable only for applications with significantly reduced current requirements and operates within 2.7V to 4.5V supply range.

Compliance and Certification:

All substitute parts maintain ROHS3 compliance and REACH Unaffected status, matching the original part's regulatory standing. All parts carry EAR99 ECCN classification and 8542.39.xxxx HTSUS codes consistent with LED driver IC categorization.

Frequently Asked Questions (FAQ)

Q: Can TPS61161ADRVR or TPS61161DRVR directly replace LM3557SD-2/NOPB in existing designs?

A: Direct replacement requires design verification. Both TPS61161 variants provide Step-Up (Boost) topology with 2.7V minimum supply voltage and -40°C to 85°C operation. However, the current output is reduced from 800mA to 700mA, and the package changes from 8-WSON (3x3) to 6-WSON (2x2). PCB layout modifications are necessary. Verify that 700mA output current meets application brightness requirements before implementation.

Q: What is the primary difference between TPS61161ADRVR and TPS61161DRVR?

A: Both parts are functionally identical with matching electrical specifications, topology, and operating parameters. The designation difference reflects packaging or tape configuration variants. Inventory availability and supplier allocation typically determine which variant is selected.

Q: Why does AP3031KTR-G1 have higher current output (1.4A) than the original LM3557SD-2/NOPB (800mA)?

A: AP3031KTR-G1 is designed for higher-brightness LED applications and incorporates a more robust internal switch structure. The increased current capability does not require design changes if the original application operates below 800mA. The part operates safely at reduced current levels. However, thermal management and PCB current routing must accommodate the higher maximum capability.

Q: Is the LTC3201EMS#PBF suitable as a substitute for LM3557SD-2/NOPB?

A: LTC3201EMS#PBF is not recommended as a direct substitute. This part operates on Switched Capacitor (Charge Pump) topology with only 100mA output current, compared to the original 800mA. The supply voltage range is also restricted to 2.7V to 4.5V. This part is suitable only for low-current LED applications such as indicator lights or minimal backlight configurations.

Q: What are the package considerations when substituting MIC2293-34YML-TR for LM3557SD-2/NOPB?

A: MIC2293-34YML-TR uses an 8-MLF® (2x2) package compared to the original 8-WSON (3x3). The MLF package is smaller in footprint but maintains 8-pin configuration. PCB layout redesign is required to accommodate the different package dimensions and pin spacing. Thermal pad design must be verified to ensure adequate heat dissipation at 750mA output current.

Q: Can MIC3223YTSE-TR replace LM3557SD-2/NOPB in backlight applications?

A: MIC3223YTSE-TR is not recommended for direct backlight replacement. This part requires a minimum 4.5V supply voltage, compared to the original 2.7V minimum. Applications operating from lower voltage sources (such as single-cell lithium batteries at 2.7V to 3.7V) cannot use this part. Additionally, the 16-TSSOP-EP package is significantly larger than the original 8-WSON (3x3), requiring substantial PCB redesign.

Q: What is the significance of the extended temperature range in Microchip parts (MIC2293-34YML-TR, MIC2299-15YML-TR, MIC3223YTSE-TR)?

A: Microchip parts operate to -40°C to 125°C (TJ), compared to the original -40°C to 85°C (TA). The extended upper temperature limit provides thermal margin for applications in high-ambient-temperature environments or where the IC experiences elevated self-heating. This extended range does not require design changes but offers improved reliability in thermally demanding applications.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance and REACH Unaffected status, matching the original LM3557SD-2/NOPB regulatory classification. No additional compliance documentation is required for substitution in ROHS3-regulated applications.

Q: What is the difference between Step-Up (Boost) and Switched Capacitor (Charge Pump) topologies?

A: Step-Up (Boost) regulators use an inductor and switching circuit to increase voltage from input to output. Switched Capacitor (Charge Pump) devices use capacitors and switching to achieve voltage multiplication. Boost regulators typically provide higher efficiency and better current capability. Charge pump devices are simpler but limited to lower current outputs. LTC3201EMS#PBF uses charge pump topology and is restricted to 100mA output, making it unsuitable for most backlight applications requiring 800mA.

Q: Can LTC3454EDD#PBF be used in place of LM3557SD-2/NOPB?

A: LTC3454EDD#PBF provides Step-Down (Buck) and Step-Up (Boost) dual topology with 1A output current. While the Step-Up mode supports backlight operation, the dual-topology design adds complexity and cost. This part is suitable for applications requiring both voltage step-up and step-down functionality. For backlight-only applications, single-topology parts (TPS61161 or AP3031) are more cost-effective.

Q: What supply voltage range is required for substitute part selection?

A: The original LM3557SD-2/NOPB operates from 2.7V to 7.5V input. Most substitute parts support 2.7V minimum input, ensuring compatibility with low-voltage sources. However, maximum supply voltage varies: TPS61161 supports 18V, AP3031 supports 16V, MIC2293 supports 10V, and MIC3223 supports 20V. Verify that the selected substitute's maximum supply voltage accommodates the application's input source.

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