UA78L09ACLP Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The UA78L09ACLP is a linear voltage regulator IC manufactured by Texas Instruments, designed to provide a fixed positive 9V output at 100mA. This Through Hole mounted device operates across an input voltage range of up to 24V with a maximum dropout voltage of 1.7V at 40mA. The part is currently in Last Time Buy status, making identification of equivalent and substitute components essential for ongoing design support and production continuity. The device includes integrated protection features for over-current, over-temperature, reverse polarity, and short-circuit conditions, operating reliably across 0°C to 125°C.

Key Parameters

Parameter	Value
Output Configuration	Positive
Output Type	Fixed
Voltage - Output (Fixed)	9V
Voltage - Input (Max)	24V
Current - Output	100mA
Voltage Dropout (Max)	1.7V @ 40mA
Operating Temperature	0°C ~ 125°C
Mounting Type	Through Hole
Package / Case	TO-92-3 (TO-226AA)
Protection Features	Over Current, Over Temperature, Reverse Polarity, Short Circuit

Substitute Part Grouping Explanation

Substitution for the UA78L09ACLP is determined by the following critical parameters: fixed 9V positive output, 100mA output current capability, Through Hole TO-92-3 package compatibility, and integrated protection features. Equivalent parts must maintain identical output voltage and current specifications while supporting the same input voltage range and operating temperature window.

The substitute parts are grouped into two categories:

Parametric Equivalents (Direct Functional Replacements): UA78L09ACLPE3 and MC78L09ACPG maintain identical 9V fixed output, 100mA current rating, and TO-92-3 package configuration. These parts are pin-compatible and functionally interchangeable within the same circuit topology.

Direct Manufacturer Equivalent: L78L09ABZ from STMicroelectronics provides the same 9V fixed output and 100mA current specification in TO-92-3 package, with extended operating temperature range (-40°C to 125°C) and improved quiescent current characteristics.

MFR Recommended Alternative: TPS7B8401QWDRBRQ1 represents a higher-performance alternative with adjustable output (1.2V to 18V), increased current capability (150mA), and superior dropout voltage (0.245V @ 150mA). This part requires circuit redesign due to Surface Mount packaging and adjustable output configuration, but offers enhanced performance metrics and Active product status.

Parameter Comparison

Parameter	UA78L09ACLP	UA78L09ACLPE3	MC78L09ACPG	L78L09ABZ	TPS7B8401QWDRBRQ1
Manufacturer	Texas Instruments	Texas Instruments	onsemi	STMicroelectronics	Texas Instruments
Output Configuration	Positive	Positive	Positive	Positive	Positive
Output Type	Fixed	Fixed	Fixed	Fixed	Adjustable
Voltage - Output	9V	9V	9V	9V	1.2V - 18V
Voltage - Input (Max)	24V	24V	30V	30V	40V
Current - Output	100mA	100mA	100mA	100mA	150mA
Voltage Dropout (Max)	1.7V @ 40mA	1.7V @ 40mA	Not specified	Not specified	0.245V @ 150mA
Operating Temperature	0°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 150°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Surface Mount
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	8-VDFN
Product Status	Last Time Buy	Last Time Buy	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	Not applicable

Engineering Selection Recommendations

For Direct Pin-Compatible Replacement: MC78L09ACPG from onsemi is the preferred choice among Through Hole TO-92-3 equivalents. This part maintains Active product status, ensuring long-term availability and supply chain stability. The device is ROHS3 compliant and provides identical electrical specifications to the UA78L09ACLP with no circuit modifications required.

For Extended Temperature Range Applications: L78L09ABZ from STMicroelectronics extends the operating temperature range to -40°C to 125°C while maintaining the same 9V fixed output and 100mA current rating in TO-92-3 package. This part is Active and ROHS3 compliant, suitable for industrial and automotive environments requiring broader temperature support.

For Performance Enhancement with Design Flexibility: TPS7B8401QWDRBRQ1 offers superior electrical characteristics including lower dropout voltage (0.245V vs 1.7V), higher output current (150mA), and adjustable output voltage capability. This part requires Surface Mount assembly and circuit redesign to accommodate adjustable output configuration, but provides Active product status and automotive-grade qualification (AEC-Q100). Selection of this alternative is appropriate when design constraints permit Surface Mount implementation and adjustable output voltage is beneficial.

Frequently Asked Questions (FAQ)

Q: Can UA78L09ACLPE3 be used as a direct replacement for UA78L09ACLP?

A: Yes. UA78L09ACLPE3 is a parametric equivalent with identical electrical specifications, fixed 9V output, 100mA current rating, and TO-92-3 Through Hole package. No circuit modifications are required for substitution.

Q: What is the primary difference between MC78L09ACPG and L78L09ABZ?

A: Both parts provide 9V fixed output at 100mA in TO-92-3 package. L78L09ABZ extends the operating temperature range to -40°C to 125°C compared to MC78L09ACPG's 0°C to 125°C range. L78L09ABZ also specifies lower quiescent current (5.5mA vs 6mA). Selection depends on application temperature requirements.

Q: Why is TPS7B8401QWDRBRQ1 listed as an alternative if it requires circuit redesign?

A: TPS7B8401QWDRBRQ1 is included as a manufacturer-recommended alternative for applications where design flexibility permits Surface Mount assembly and adjustable output voltage is advantageous. The part offers superior performance metrics including 50% lower dropout voltage and 50% higher output current. This option is suitable for new designs or redesign initiatives, not for direct board-level substitution.

Q: Are all substitute parts ROHS3 compliant?

A: The Through Hole TO-92-3 equivalents (UA78L09ACLPE3, MC78L09ACPG, and L78L09ABZ) are ROHS3 compliant. TPS7B8401QWDRBRQ1 lists RoHS status as Not applicable due to its Surface Mount package classification.

Q: What protection features are common across all substitute parts?

A: All substitute parts include Over Temperature and Short Circuit protection. Over Current protection is present in UA78L09ACLPE3, L78L09ABZ, and the original UA78L09ACLP. MC78L09ACPG omits Over Current protection. Reverse Polarity protection is unique to the original UA78L09ACLP and UA78L09ACLPE3.

Q: Can these parts be used interchangeably in existing PCB designs?

A: UA78L09ACLPE3, MC78L09ACPG, and L78L09ABZ are pin-compatible Through Hole TO-92-3 devices and can be used interchangeably without PCB modifications. TPS7B8401QWDRBRQ1 requires PCB redesign due to Surface Mount 8-VDFN package and adjustable output configuration.

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