LM7809CT Equivalent & Substitute Parts

Part Overview

The LM7809CT is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 9V output at 1A current capacity in a TO-220-3 through-hole package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The LM7809CT serves applications requiring stable 9V regulation from input sources up to 35V with integrated over-temperature and short-circuit protection.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	9V
Output Current	1A
Input Voltage (Max)	35V
Voltage Dropout (Typ)	2V @ 1A
Quiescent Current	8 mA
PSRR	71dB (120Hz)
Operating Temperature Range	-40°C ~ 125°C
Package Type	TO-220-3
Protection Features	Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitution eligibility for the LM7809CT is determined by the following critical parameters: fixed 9V output voltage, output current capacity, maximum input voltage rating (35V), package type (TO-220-3), and protection features (over-temperature and short-circuit). Parts are grouped into three categories based on output current capability and product status:

Category 1: Direct Current Rating Match (1A Output) Parts with 1A output current matching the LM7809CT specification: MC7809ACTG, MC7809CTG, and MC7809BTG from onsemi, plus L7809ABV-DG and L7809CV from STMicroelectronics.

Category 2: Reduced Current Rating (500mA Output) Parts with 500mA output current: MC78M09CTG (onsemi) and L78M09CV (STMicroelectronics). These are suitable only where application current requirements do not exceed 500mA.

Category 3: Increased Current Rating (1.5A–2A Output) Parts with higher output current capacity: L7809ABV-DG (1.5A) and L78S09CV (2A) from STMicroelectronics. These provide enhanced current capability for applications requiring higher load capacity.

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Max)	Dropout Voltage	Quiescent Current	PSRR (120Hz)	Operating Temp	Product Status	RoHS Status
LM7809CT	onsemi	1A	35V	2V @ 1A	8 mA	71dB	-40°C ~ 125°C	Obsolete	Not Specified
MC7809ACTG	onsemi	1A	35V	2V @ 1A	6 mA	61dB	0°C ~ 125°C	Obsolete	ROHS3 Compliant
MC7809CTG	onsemi	1A	35V	2V @ 1A	8 mA	61dB	0°C ~ 125°C	Active	ROHS3 Compliant
MC78M09CTG	onsemi	500mA	35V	Not Specified	Not Specified	80dB	0°C ~ 125°C	Obsolete	ROHS3 Compliant
L7809ABV-DG	STMicroelectronics	1.5A	35V	2V @ 1A	6 mA	61dB	-40°C ~ 125°C	Obsolete	ROHS3 Compliant
L7809CV	STMicroelectronics	1.5A	35V	2V @ 1A	8 mA	55dB	0°C ~ 125°C	Obsolete	ROHS3 Compliant
L78M09CV	STMicroelectronics	500mA	35V	Not Specified	6 mA	56dB	0°C ~ 125°C	Obsolete	ROHS3 Compliant
L78S09CV	STMicroelectronics	2A	35V	Not Specified	8 mA	47dB	0°C ~ 150°C	Obsolete	ROHS3 Compliant
MC7809BTG	onsemi	1A	35V	2V @ 1A	8 mA	61dB	-40°C ~ 125°C	Obsolete	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: MC7809CTG MC7809CTG is the preferred substitute for new designs and production continuity. It maintains the 1A output current specification, 35V maximum input voltage, and TO-220-3 package compatibility with the LM7809CT. Critically, MC7809CTG holds Active product status, ensuring long-term availability and supply chain stability. The part is ROHS3 compliant and carries REACH Unaffected certification, meeting modern regulatory requirements. Inventory availability of 23,318 units supports immediate procurement.

Secondary Recommendation: L7809CV (STMicroelectronics) L7809CV provides a direct functional equivalent with 1.5A output current capacity, exceeding the LM7809CT specification. This higher current rating offers design margin for applications with variable load conditions. The part maintains -40°C to 125°C operating temperature compatibility with the original specification and includes ROHS3 compliance. With 204,200 units in stock, supply continuity is assured. The reduced PSRR (55dB versus 71dB) should be evaluated for noise-sensitive applications.

Temperature Range Consideration: MC7809BTG For applications requiring the full -40°C to 125°C operating temperature range of the LM7809CT, MC7809BTG from onsemi provides an exact parametric match. This part is suitable where extended low-temperature operation is mandatory. However, obsolete product status requires verification of long-term availability.

Current-Limited Applications: MC78M09CTG or L78M09CV Where application current requirements do not exceed 500mA, MC78M09CTG or L78M09CV provide reduced-current alternatives. MC78M09CTG offers superior PSRR performance (80dB) compared to the LM7809CT, beneficial for noise-critical circuits. Both parts are obsolete; selection should prioritize current inventory levels.

Higher Current Requirement: L78S09CV Applications requiring output current exceeding 1A should use L78S09CV, which provides 2A capacity. This part extends the operating temperature range to 150°C and includes over-current protection in addition to over-temperature and short-circuit protection. Obsolete status requires supply verification.

Frequently Asked Questions (FAQ)

Q: Can MC7809CTG directly replace LM7809CT in existing designs? A: Yes. MC7809CTG maintains identical electrical specifications for output voltage (9V), output current (1A), maximum input voltage (35V), and package type (TO-220-3). The primary difference is operating temperature range: MC7809CTG operates 0°C to 125°C versus LM7809CT at -40°C to 125°C. Verify your application's minimum operating temperature requirement before substitution.

Q: What is the difference between MC7809CTG and MC7809ACTG? A: Both are onsemi 9V, 1A regulators in TO-220-3 packages. MC7809CTG is Active product status with current availability (23,318 units). MC7809ACTG is Obsolete with lower inventory (1,685 units). MC7809ACTG has slightly lower quiescent current (6 mA versus 8 mA) and reduced PSRR (61dB versus 61dB). For new designs, MC7809CTG is preferred due to active status.

Q: Can I use L7809CV instead of LM7809CT? A: Yes, with considerations. L7809CV provides 1.5A output current, exceeding the 1A requirement, offering design margin. However, PSRR is reduced (55dB versus 71dB), which may affect noise performance in sensitive applications. Operating temperature is 0°C to 125°C, not -40°C to 125°C. Verify these parameters against your application requirements.

Q: What does "Obsolete" product status mean for substitution? A: Obsolete status indicates the manufacturer has discontinued active production. Substitutes with Obsolete status rely on existing inventory. MC7809CTG, with Active status, is the only current-production option and should be prioritized for new designs to ensure long-term supply availability.

Q: Are all substitute parts ROHS3 compliant? A: All STMicroelectronics parts (L7809ABV-DG, L7809CV, L78M09CV, L78S09CV) and onsemi parts (MC7809ACTG, MC7809CTG, MC78M09CTG, MC7809BTG) are ROHS3 compliant. The original LM7809CT does not specify RoHS status. Verify compliance requirements for your application before final selection.

Q: Which substitute provides the best noise performance? A: MC78M09CTG offers the highest PSRR at 80dB (120Hz), followed by LM7809CT at 71dB. For noise-critical applications, MC78M09CTG is preferred, though it is limited to 500mA output current. If 1A output is required, MC7809CTG (61dB PSRR) is the best available option.

Q: Can I use a higher-current part like L78S09CV (2A) in place of LM7809CT (1A)? A: Yes. Higher-current regulators are backward-compatible with lower-current applications. L78S09CV provides 2A capacity, exceeding the 1A requirement, and extends operating temperature to 150°C. This substitution is suitable for applications where additional current margin is beneficial. Verify package compatibility and PCB thermal design for the higher current capability.

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