LM1086CSX-ADJ Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LM1086CSX-ADJ is a linear positive adjustable voltage regulator IC manufactured by Texas Instruments, designed for 1.5A output applications in TO-263 (DDPAK-3) surface mount packaging. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. The LM1086CSX-ADJ provides adjustable output voltage regulation from 1.2V to 15V with integrated over-current, over-temperature, and short-circuit protection.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Part Number	LM1086CSX-ADJ
Product Status	Obsolete
Output Configuration	Positive
Output Type	Adjustable
Current Output	1.5A
Voltage Input (Max)	29V
Voltage Output (Min)	1.2V
Voltage Output (Max)	15V
Voltage Dropout (Max)	1.5V @ 1.5A
Quiescent Current	5 mA
PSRR	75dB (120Hz)
Protection Features	Over Current, Over Temperature, Short Circuit
Operating Temperature	0°C ~ 125°C
Package	TO-263 (DDPAK-3)
Mounting Type	Surface Mount
RoHS Status	Non-compliant

Substitute Part Grouping Explanation

Substitution of the LM1086CSX-ADJ is determined by the following critical parameters:

Electrical Compatibility Requirements:

Output configuration (positive adjustable)
Current output rating (1.5A minimum)
Voltage input maximum (≥29V)
Voltage output range (minimum ≤1.2V, maximum ≥15V)
Voltage dropout (≤1.5V @ 1.5A)
Protection features (over-current, over-temperature, short-circuit)

Mechanical Compatibility Requirements:

Package type (TO-263 or D2PAK variants)
Surface mount mounting type
Pin configuration compatibility

Compliance Requirements:

RoHS status for new designs
Moisture sensitivity level
REACH compliance status

Substitute parts are grouped into three categories: parametric equivalents from Texas Instruments with active product status, direct manufacturer alternatives from STMicroelectronics and onsemi, and manufacturer-recommended alternatives from Analog Devices Inc.

Parameter Comparison

Parameter	LM1086CSX-ADJ	LM1086CSX-ADJ/NOPB	LD1086D2MTR	LM317BD2TR4G	LT1086CM#PBF	LT1086CM#TRPBF	LT1086IM#PBF	LT1086IM#TRPBF
Manufacturer	Texas Instruments	Texas Instruments	STMicroelectronics	onsemi	Analog Devices	Analog Devices	Analog Devices	Analog Devices
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active
Output Configuration	Positive	Positive	Positive	Positive	Positive	Positive	Positive	Positive
Output Type	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable
Current Output	1.5A	1.5A	1.5A	1.5A	1.5A	1.5A	1.5A	1.5A
Voltage Input (Max)	29V	29V	30V	40V	25V	25V	25V	25V
Voltage Output (Min)	1.2V	1.2V	1.25V	1.2V	1.25V	1.25V	1.25V	1.25V
Voltage Output (Max)	15V	15V	28.5V	37V	24.6V	24.6V	24.6V	24.6V
Voltage Dropout (Max)	1.5V @ 1.5A	1.5V @ 1.5A	1.5V @ 1.5A	Not specified	1.5V @ 1.5A	1.5V @ 1.5A	1.5V @ 1.5A	1.5V @ 1.5A
Quiescent Current	5 mA	5 mA	10 mA	10 mA	Not specified	Not specified	Not specified	Not specified
PSRR	75dB (120Hz)	75dB (120Hz)	88dB (120Hz)	80dB ~ 65dB (120Hz)	75dB (120Hz)	75dB (120Hz)	75dB (120Hz)	75dB (120Hz)
Protection Features	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature	Over Current, Over Temperature	Over Current, Over Temperature	Over Current, Over Temperature
Operating Temperature	0°C ~ 125°C	0°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C
Package	TO-263 (DDPAK-3)	TO-263 (DDPAK-3)	D2PAK	D2PAK-3	TO-263 (DDPAK-3)	TO-263 (DDPAK-3)	TO-263 (DDPAK-3)	TO-263 (DDPAK-3)
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL	3 (168 Hours)	3 (168 Hours)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Recommendation: LM1086CSX-ADJ/NOPB

The LM1086CSX-ADJ/NOPB is the direct parametric equivalent from Texas Instruments with active product status. This part maintains identical electrical specifications and package configuration while offering ROHS3 compliance and improved availability. Selection of this part eliminates obsolescence risk and provides the most direct design continuity.

Secondary Recommendation: LT1086 Series (Analog Devices)

The LT1086CM#TRPBF, LT1086CM#PBF, LT1086IM#PBF, and LT1086IM#TRPBF variants from Analog Devices provide active product status with identical package compatibility (TO-263 DDPAK-3). These parts offer ROHS3 compliance and unlimited moisture sensitivity rating. The LT1086IM variants support extended operating temperature range (-40°C to 125°C) compared to the original part specification. Output voltage range is limited to 24.6V maximum, which is acceptable for applications requiring output voltages up to 15V.

Alternative Recommendation: LD1086D2MTR (STMicroelectronics)

The LD1086D2MTR provides active product status with enhanced specifications including 30V maximum input voltage and 88dB PSRR. This part features unlimited moisture sensitivity rating and extended operating temperature range. Package compatibility is maintained through D2PAK configuration. Output voltage range extends to 28.5V, providing additional design margin.

Extended Range Alternative: LM317BD2TR4G (onsemi)

The LM317BD2TR4G offers the highest input voltage rating (40V maximum) and extended output voltage range (37V maximum) with active product status and ROHS3 compliance. This part is suitable for applications requiring higher input voltage tolerance or extended output voltage adjustment range. Package configuration is D2PAK-3 with pin compatibility considerations required.

Compliance Considerations:

All recommended substitute parts except the original LM1086CSX-ADJ are ROHS3 compliant, meeting modern environmental and regulatory requirements. Parts from Analog Devices and STMicroelectronics feature unlimited moisture sensitivity rating (MSL 1), eliminating moisture-related handling constraints present in the original part (MSL 3).

Frequently Asked Questions (FAQ)

Q: Can LM1086CSX-ADJ/NOPB be used as a direct replacement for LM1086CSX-ADJ?

A: Yes. The LM1086CSX-ADJ/NOPB is a parametric equivalent with identical electrical specifications, package configuration, and pin assignment. The primary difference is active product status and ROHS3 compliance. No circuit modifications are required.

Q: What is the difference between LT1086 variants (CM#PBF, CM#TRPBF, IM#PBF, IM#TRPBF)?

A: The suffix designations indicate packaging and temperature range. CM variants operate at 0°C to 125°C, while IM variants support -40°C to 125°C. PBF indicates tube packaging, while TRPBF and TR indicate tape and reel packaging. Electrical specifications remain identical across all variants.

Q: Are there package compatibility issues between TO-263 (DDPAK-3) and D2PAK variants?

A: TO-263 (DDPAK-3) and D2PAK are mechanically and electrically compatible packages with identical pin configurations and thermal characteristics. Both are surface mount packages with three leads plus tab. PCB layout modifications are not required for substitution.

Q: Which substitute part has the lowest quiescent current?

A: The LM1086CSX-ADJ and LM1086CSX-ADJ/NOPB both specify 5 mA quiescent current. The LD1086D2MTR, LM317BD2TR4G, and all LT1086 variants specify 10 mA quiescent current. For applications sensitive to standby power consumption, the Texas Instruments variants are preferred.

Q: Can LM317BD2TR4G replace LM1086CSX-ADJ in all applications?

A: The LM317BD2TR4G is electrically compatible for applications requiring output voltages up to 15V and input voltages up to 40V. However, the package configuration is D2PAK-3 (2 leads plus tab) rather than DDPAK-3 (3 leads plus tab). Pin assignment differences require circuit verification before substitution.

Q: What is the impact of output voltage range differences on substitution?

A: The original LM1086CSX-ADJ supports output voltage adjustment from 1.2V to 15V. Substitute parts from Analog Devices (LT1086 series) limit maximum output to 24.6V, while LD1086D2MTR extends to 28.5V and LM317BD2TR4G to 37V. For applications requiring output voltages between 15V and 24.6V, the LT1086 series is suitable. For applications limited to 15V output, all substitute parts are compatible.

Q: Are there REACH compliance differences between substitute parts?

A: All parts listed, including the original LM1086CSX-ADJ, maintain REACH Unaffected status. No REACH compliance restrictions apply to any substitute part.

Q: Which substitute part offers the best moisture handling characteristics?

A: The original LM1086CSX-ADJ specifies MSL 3 (168 hours), requiring controlled moisture exposure during storage and handling. All substitute parts specify MSL 1 (Unlimited), eliminating moisture sensitivity constraints. This represents a significant advantage for supply chain management and long-term storage.

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