LF90CV Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LF90CV is a linear voltage regulator IC manufactured by STMicroelectronics, designed to provide a fixed positive 9V output at 500mA in a TO-220-3 package. This device is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and component procurement.

The LF90CV operates as a single-output positive fixed regulator with integrated over-current and over-temperature protection. Its primary application is in power management circuits requiring stable 9V regulation from input sources up to 16V with moderate current demands.

Substiute Parts

LF90CV

STMicroelectronicsIn Stock: 10396LF90CV Datasheet

Current PartRFQ

LM2940CT-9.0/NOPB

National SemiconductorIn Stock: 1738LM2940CT-9.0/NOPB Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the LF90CV is determined by the following critical parameters:

1. Output Voltage: The substitute must provide a fixed 9V output
2. Output Current Capability: The substitute must support at least 500mA continuous output
3. Package Configuration: The substitute must be available in TO-220-3 through-hole mounting
4. Input Voltage Range: The substitute must accept input voltages up to at least 16V
5. Protection Features: The substitute must include over-current and over-temperature protection
6. Output Configuration: The substitute must be a positive fixed regulator with single output

The LM2940CT-9.0/NOPB meets these substitution criteria. It provides the same 9V fixed output, operates in the same TO-220-3 package, and includes all required protection features. The LM2940CT-9.0/NOPB exceeds the minimum current requirement at 1A output capability and accepts higher input voltages (26V maximum), making it a direct functional replacement.

Parameter Comparison

Engineering Selection Recommendations

The LM2940CT-9.0/NOPB is a suitable substitute for the obsolete LF90CV based on the following engineering criteria:

Functional Equivalence: Both devices provide fixed 9V regulation in identical TO-220-3 packages with through-hole mounting. The LM2940CT-9.0/NOPB output current rating of 1A exceeds the LF90CV requirement of 500mA, ensuring adequate headroom for the application.

Compliance and Certification: Both parts carry EAR99 ECCN classification and HTSUS code 8542.39.0001. The LM2940CT-9.0/NOPB is RoHS compliant and currently in active production status, ensuring long-term availability and supply chain stability.

Protection Architecture: The LM2940CT-9.0/NOPB incorporates additional protection features including reverse polarity and short-circuit protection beyond the over-current and over-temperature protection present in the LF90CV.

Operating Conditions: The LM2940CT-9.0/NOPB accepts input voltages up to 26V, providing greater design margin than the LF90CV 16V maximum. The operating temperature range of 0°C to 125°C covers the upper portion of the LF90CV range; applications requiring operation below 0°C require evaluation of specific environmental requirements.

Quiescent Current Consideration: The LM2940CT-9.0/NOPB quiescent current of 10mA is higher than the LF90CV at 1.5mA. In battery-powered or low-power standby applications, this difference may require circuit design review.

Frequently Asked Questions (FAQ)

Q: Can the LM2940CT-9.0/NOPB directly replace the LF90CV in existing PCB designs?

A: Yes. Both devices use identical TO-220-3 package pinouts and provide 9V fixed output. No PCB modifications are required for pin-to-pin substitution. However, circuit designers should verify that the higher quiescent current of the LM2940CT-9.0/NOPB does not impact power budget calculations in low-power applications.

Q: What is the primary reason the LF90CV requires substitution?

A: The LF90CV is classified as obsolete. The LM2940CT-9.0/NOPB is an active product currently manufactured by National Semiconductor, ensuring continued availability and supply chain support.

Q: Are there differences in thermal performance between these regulators?

A: Both devices are housed in TO-220-3 packages with identical thermal characteristics. Thermal management considerations depend on application-specific current draw and ambient temperature conditions rather than device selection.

Q: Does the LM2940CT-9.0/NOPB require different PCB layout or decoupling?

A: Standard linear regulator PCB layout practices apply to both devices. Input and output decoupling capacitors should be placed close to the device pins. Specific capacitor values and types should follow the regulator manufacturer's datasheet recommendations.

Q: What is the significance of the higher input voltage rating on the LM2940CT-9.0/NOPB?

A: The LM2940CT-9.0/NOPB accepts input voltages up to 26V compared to the LF90CV maximum of 16V. This provides additional design margin and allows the substitute to function in applications with higher input voltage sources without modification.

Q: Is the additional reverse polarity protection on the LM2940CT-9.0/NOPB beneficial?

A: Yes. The integrated reverse polarity protection on the LM2940CT-9.0/NOPB provides circuit protection against accidental input polarity reversal without requiring external diodes, simplifying circuit design and improving reliability.

Q: Can the LM2940CT-9.0/NOPB be used in applications requiring operation below 0°C?

A: The LM2940CT-9.0/NOPB operating temperature range begins at 0°C. Applications requiring operation below 0°C must either retain the LF90CV (if available from inventory) or identify alternative regulators with extended low-temperature specifications.