LM340AT-5.0 Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LM340AT-5.0 is a linear voltage regulator IC manufactured by Texas Instruments, designed to provide a fixed 5V positive output with 1.5A current capacity in a TO-220-3 package. This device is classified as Last Time Buy, indicating limited availability from the original manufacturer. Identifying equivalent and substitute parts is necessary to ensure design continuity, maintain supply chain flexibility, and support long-term production requirements.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	5V
Output Current	1.5A
Input Voltage (Max)	35V
Voltage Dropout (Max)	2V @ 1A
Quiescent Current	6 mA
PSRR	70dB (120Hz)
Protection Features	Over Current, Short Circuit
Operating Temperature	0°C ~ 125°C
Package	TO-220-3
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the LM340AT-5.0 is determined by the following critical parameters:

Output Voltage: Must be fixed at 5V
Output Current Capacity: Minimum 1.5A required for direct substitution; lower current ratings (500mA, 1A, 100mA) are acceptable only if circuit design permits reduced current delivery
Input Voltage Rating: Must support maximum 35V input
Package Type: TO-220-3 mounting required for mechanical compatibility
Voltage Dropout: Maximum 2V @ 1A for thermal performance equivalence
Protection Features: Over current and short circuit protection required
Operating Temperature Range: 0°C ~ 125°C minimum
Compliance: ROHS3 compliant

Substitute parts are grouped into three categories based on output current capacity and manufacturer:

Direct Current Equivalents (1.5A): Parts with identical 1.5A output current
Reduced Current Alternatives (500mA - 1.2A): Parts with lower current ratings suitable for applications with reduced power requirements
Low Current Regulators (100mA): Specialized low-current variants for specific applications

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Max)	Dropout Voltage	Operating Temp	Product Status	PSRR (120Hz)
LM340AT-5.0	Texas Instruments	1.5A	35V	2V @ 1A	0°C ~ 125°C	Last Time Buy	70dB
LM340AT-5.0/NOPB	Texas Instruments	1.5A	35V	2V @ 1A	0°C ~ 125°C	Active	70dB
L7805ABV	STMicroelectronics	1.5A	35V	2V @ 1A (Typ)	-40°C ~ 125°C	Active	68dB
L7805ACV	STMicroelectronics	1.5A	35V	2V @ 1A (Typ)	0°C ~ 125°C	Active	68dB
L7805CV	UMW	1.2A	35V	—	-40°C ~ 105°C	Active	—
L78M05ABV	STMicroelectronics	500mA	35V	—	-40°C ~ 125°C	Active	62dB
L78M05CV	STMicroelectronics	500mA	35V	—	0°C ~ 150°C	Active	62dB
L78S05CV	STMicroelectronics	2A	35V	—	0°C ~ 150°C	Obsolete	54dB
LM2931AT-5.0G	onsemi	100mA	26V	0.6V @ 100mA	-40°C ~ 125°C	Active	90dB
LM2931T-5.0G	onsemi	100mA	26V	0.6V @ 100mA	-40°C ~ 125°C	Active	90dB
MC7805ABTG	onsemi	1A	35V	2V @ 1A (Typ)	-40°C ~ 125°C	Active	83dB

Engineering Selection Recommendations

Primary Substitutes (Direct Equivalents)

LM340AT-5.0/NOPB is the preferred direct substitute. This part is electrically and mechanically identical to the LM340AT-5.0, with the primary distinction being active product status versus Last Time Buy. Both parts share identical electrical specifications, package configuration, and compliance certifications. The /NOPB designation indicates lead-free plating, consistent with ROHS3 compliance requirements.

L7805ACV and L7805ABV from STMicroelectronics provide functional equivalence with 1.5A output current and 35V maximum input voltage. L7805ACV operates within the 0°C ~ 125°C temperature range matching the original part, while L7805ABV extends the lower operating limit to -40°C. Both maintain ROHS3 compliance and are in active production status.

Secondary Substitutes (Reduced Current Capacity)

L7805CV from UMW provides 1.2A output current, suitable for applications where the full 1.5A capacity is not required. This part maintains 35V input voltage rating and ROHS3 compliance but operates within -40°C ~ 105°C temperature range.

L78M05ABV and L78M05CV from STMicroelectronics deliver 500mA output current with enhanced protection features including over current, over temperature, and short circuit protection. These parts are appropriate for low-power applications and maintain 35V input voltage rating and ROHS3 compliance.

Specialized Alternatives

LM2931AT-5.0G and LM2931T-5.0G from onsemi are low-current regulators rated at 100mA with superior PSRR performance (90dB). These parts are suitable only for applications with minimal current requirements and operate within a reduced input voltage range (26V maximum). Input voltage limitation must be evaluated against circuit requirements.

L78S05CV from STMicroelectronics is classified as Obsolete and should not be selected for new designs despite higher 2A output current rating.

Frequently Asked Questions (FAQ)

Q: Can LM340AT-5.0/NOPB be used as a direct replacement for LM340AT-5.0?

A: Yes. LM340AT-5.0/NOPB is electrically and mechanically identical to LM340AT-5.0. The primary difference is product status (Active versus Last Time Buy) and lead-free plating designation. Both parts meet ROHS3 compliance and share identical electrical specifications.

Q: What is the difference between L7805ACV and L7805ABV?

A: Both parts provide 1.5A output current and 35V maximum input voltage. The primary difference is operating temperature range: L7805ACV operates 0°C ~ 125°C (matching the original LM340AT-5.0), while L7805ABV extends to -40°C ~ 125°C. Selection depends on application temperature requirements.

Q: Can L78M05ABV or L78M05CV replace LM340AT-5.0 in all applications?

A: No. These parts are rated at 500mA output current, compared to 1.5A for the LM340AT-5.0. They are suitable only for applications where circuit current requirements do not exceed 500mA. Thermal design and power dissipation must be re-evaluated.

Q: Why is L78S05CV not recommended despite its 2A output current?

A: L78S05CV is classified as Obsolete product status. New designs should not incorporate obsolete components due to supply chain risk and potential manufacturing discontinuation.

Q: What are the input voltage limitations for LM2931AT-5.0G and LM2931T-5.0G?

A: These parts are rated for maximum 26V input voltage, compared to 35V for the LM340AT-5.0. They are suitable only for applications where input voltage does not exceed 26V. These parts are optimized for low-current applications (100mA) and should not be selected for higher current requirements.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed in this document are ROHS3 compliant and meet REACH compliance requirements. All parts are suitable for applications requiring environmental compliance certification.

Q: What package considerations apply to these substitutes?

A: All substitute parts use TO-220-3 package configuration, providing mechanical compatibility with LM340AT-5.0. PCB layout and thermal management design do not require modification for package-compatible substitutes.

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