FAN1540DX Equivalent & Substitute Parts

Part Overview

The FAN1540DX is a linear voltage regulator IC manufactured by onsemi, designed to deliver a fixed 3.3V output at 1.3A maximum current in a surface-mount TO-252-3 (DPAK) package. This device is classified as obsolete, making equivalent substitute parts necessary for new designs and production continuity. The FAN1540DX provides over-current and over-temperature protection suitable for general-purpose power management applications requiring moderate current delivery with minimal dropout voltage.

Substiute Parts

FAN1540DX

onsemiIn Stock: 851FAN1540DX Datasheet

Current PartRFQ

LP38690DTX-3.3/NOPB

Texas InstrumentsIn Stock: 19462LP38690DTX-3.3/NOPB Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the FAN1540DX is determined by the following critical parameters that must remain compatible:

• Output Voltage: Fixed 3.3V output is mandatory
• Package Type: TO-252-3 (DPAK) mechanical and electrical compatibility required
• Maximum Input Voltage: 10V maximum rating must be met or exceeded
• Output Current Capability: Minimum 1.3A required for direct replacement; lower ratings require circuit redesign
• Dropout Voltage: Lower dropout voltage improves efficiency but is not a limiting factor for substitution
• Protection Features: Over-temperature protection is standard; over-current protection is beneficial but not mandatory for substitution eligibility
• Mounting Type: Surface mount compatibility maintained across all candidates

The LP38690DTX-3.3/NOPB from Texas Instruments meets the core substitution criteria with identical output voltage, package type, and input voltage rating. While its maximum output current is rated at 1A (versus 1.3A), this represents a functional limitation that must be evaluated against actual circuit requirements.

Parameter Comparison

Engineering Selection Recommendations

The LP38690DTX-3.3/NOPB is an active, in-production substitute for the obsolete FAN1540DX. Both devices share identical output voltage (3.3V) and package configuration (TO-252-3), enabling direct PCB-level replacement without layout modifications.

The primary design consideration is the output current rating difference: the LP38690DTX-3.3/NOPB is rated for 1.0A maximum output, compared to the FAN1540DX at 1.3A. Circuit designs operating at or below 1.0A output current can use the LP38690DTX-3.3/NOPB as a direct functional substitute. Designs requiring sustained output currents between 1.0A and 1.3A must be re-evaluated or alternative regulators with higher current ratings must be selected.

The LP38690DTX-3.3/NOPB offers operational advantages including significantly lower quiescent current (55 µA versus 2 mA), extended operating temperature range (-40°C to 125°C versus 0°C to 125°C), and active product status ensuring long-term availability. The device is RoHS3 compliant and REACH unaffected, meeting modern regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can the LP38690DTX-3.3/NOPB replace the FAN1540DX in all applications?

A: Direct replacement is possible only in applications where the maximum sustained output current does not exceed 1.0A. The LP38690DTX-3.3/NOPB is rated for 1.0A maximum output, while the FAN1540DX supports 1.3A. Verify your circuit's actual current requirements before substitution.

Q: Are the packages physically identical?

A: Yes. Both devices use the TO-252-3 (DPAK) package with identical pin configuration and mechanical dimensions, allowing direct PCB-level substitution without layout changes.

Q: What is the impact of the lower quiescent current in the LP38690DTX-3.3/NOPB?

A: The LP38690DTX-3.3/NOPB draws 55 µA quiescent current compared to 2 mA for the FAN1540DX. This 36-fold reduction improves overall system efficiency, particularly in battery-powered or low-power standby applications.

Q: Does the LP38690DTX-3.3/NOPB provide over-current protection?

A: The LP38690DTX-3.3/NOPB provides over-temperature protection only. The FAN1540DX includes both over-current and over-temperature protection. If over-current protection is critical to your application, this difference must be addressed through external circuit design.

Q: What is the significance of the extended temperature range in the LP38690DTX-3.3/NOPB?

A: The LP38690DTX-3.3/NOPB operates from -40°C to 125°C, compared to 0°C to 125°C for the FAN1540DX. This extended lower temperature limit enables use in industrial and automotive environments requiring operation below 0°C.

Q: Why is the FAN1540DX obsolete?

A: The FAN1540DX is classified as obsolete by onsemi. The LP38690DTX-3.3/NOPB from Texas Instruments is an active, in-production alternative that meets the same functional requirements with improved specifications and regulatory compliance.