LA5779MP-DL-E Equivalent & Substitute Parts

Part Overview

The LA5779MP-DL-E is a buck switching regulator IC manufactured by onsemi, designed for positive adjustable output applications with 3.1A switch current capability. This component operates across a wide input voltage range of 4.5V to 28V and delivers adjustable output from 1.23V to 28V. The device is currently classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations.

Substiute Parts

LA5779MP-DL-E

onsemiIn Stock: 856LA5779MP-DL-E Datasheet

Current PartRFQ

BD9870FPS-E2

Rohm SemiconductorIn Stock: 20246BD9870FPS-E2 Datasheet

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LT3972EDD#TRPBF

Analog Devices Inc.In Stock: 9199LT3972EDD#TRPBF Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the LA5779MP-DL-E are identified based on the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

• Function: Step-down (buck) topology
• Output Configuration: Positive adjustable
• Number of Outputs: Single output
• Input Voltage Range: Minimum 4.5V or lower; Maximum 28V or higher
• Output Voltage Range: Minimum 1.23V or lower; Maximum 28V or higher
• Output Current: 3.1A or greater
• Mounting Type: Surface mount
• Package Compatibility: TO-252 series or equivalent footprint

The two identified substitutes meet these core electrical requirements while maintaining functional equivalence for buck regulation applications. Both parts support the adjustable output voltage and current specifications necessary for direct replacement in existing designs.

Parameter Comparison

Engineering Selection Recommendations

BD9870FPS-E2 (Rohm Semiconductor): This substitute provides active product status and ROHS3 compliance. The device supports the required input voltage range (8V to 35V) and adjustable output configuration. However, the maximum output current of 1.5A is below the LA5779MP-DL-E specification of 3.1A, limiting its applicability to lower-current applications. The higher switching frequency of 900kHz may reduce output filtering requirements but increases EMI considerations. The TO-252-5 package differs from the original TO-252-6, requiring PCB layout verification.

LT3972EDD#TRPBF (Analog Devices Inc.): This substitute offers active product status, ROHS3 compliance, and superior output current capability at 4.6A, exceeding the original 3.1A specification. The input voltage range (3.6V to 33V) encompasses the LA5779MP-DL-E requirements. The adjustable output voltage range (0.79V to 30V) provides extended flexibility. Operating temperature range matches the original at -40°C to 125°C. The 10-WFDFN package represents a significant footprint change from TO-252-6, requiring complete PCB redesign. The programmable switching frequency (230kHz to 2.45MHz) offers design flexibility for noise and efficiency optimization.

Frequently Asked Questions (FAQ)

Q: Can BD9870FPS-E2 directly replace LA5779MP-DL-E in existing designs? A: Electrical substitution is limited by the BD9870FPS-E2 maximum output current of 1.5A versus the original 3.1A specification. Applications requiring the full 3.1A output cannot use this substitute. Additionally, the TO-252-5 package (4 leads + tab) differs from the TO-252-6 package (5 leads + tab), requiring PCB layout modifications.

Q: Is LT3972EDD#TRPBF suitable for direct PCB replacement? A: The LT3972EDD#TRPBF provides superior electrical compatibility with 4.6A output current and matching temperature range. However, the 10-WFDFN package is fundamentally different from the TO-252-6 package, requiring complete PCB redesign. This substitute is suitable for new designs or major board revisions but not for drop-in replacement.

Q: What are the key differences in switching frequency between these parts? A: The LA5779MP-DL-E operates at fixed 160kHz. The BD9870FPS-E2 operates at 900kHz, requiring different output filter component values. The LT3972EDD#TRPBF offers programmable frequency from 230kHz to 2.45MHz, allowing optimization for specific application requirements. Higher switching frequencies reduce inductor and capacitor sizes but may increase switching losses.

Q: Are both substitutes RoHS compliant? A: Yes, both BD9870FPS-E2 and LT3972EDD#TRPBF are ROHS3 compliant. The original LA5779MP-DL-E RoHS status is not specified in available documentation.

Q: What is the impact of different operating temperature ranges? A: The BD9870FPS-E2 operates to 85°C maximum (TA), which is lower than the original 125°C (TJ) and the LT3972EDD#TRPBF 125°C (TJ). Applications requiring operation above 85°C cannot use the BD9870FPS-E2. The LT3972EDD#TRPBF maintains the full temperature range of the original part.

Q: How do input voltage ranges compare? A: The LA5779MP-DL-E accepts 4.5V to 28V input. The BD9870FPS-E2 requires minimum 8V input, making it unsuitable for applications below 8V. The LT3972EDD#TRPBF accepts 3.6V minimum input, providing extended low-voltage capability beyond the original specification.