LM78L09ACZ Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LM78L09ACZ is a linear voltage regulator IC manufactured by Texas Instruments, designed to provide a fixed positive 9V output at 100mA. This device is classified as a Power Management (PMIC) component and is packaged in TO-92-3 (TO-226AA) through-hole configuration. The part is currently listed as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity. Substitute parts must maintain electrical compatibility across output voltage, current capacity, and protection features while accommodating the through-hole mounting requirement.

Key Parameters

Parameter	LM78L09ACZ
Manufacturer	Texas Instruments
Output Voltage (Fixed)	9V
Output Current	100mA
Input Voltage (Max)	35V
Quiescent Current	2 mA
PSRR	44dB (120Hz)
Protection Features	Over Temperature, Short Circuit
Operating Temperature Range	0°C ~ 125°C
Package / Case	TO-92-3 (TO-226AA)
Mounting Type	Through Hole
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the LM78L09ACZ is determined by the following critical parameters:

Fixed output voltage of 9V
Output current capacity of 100mA minimum
Through-hole TO-92-3 package compatibility
Positive output configuration
Single regulator output
RoHS3 compliance and REACH unaffected status

The substitute parts identified maintain these core electrical and mechanical specifications. Variations in maximum input voltage, quiescent current, PSRR performance, and extended protection features do not preclude substitution when the primary functional requirements are met. Product status (active versus last time buy or obsolete) indicates availability and supply chain considerations but does not affect electrical compatibility.

Parameter Comparison

Parameter	LM78L09ACZ (TI)	L78L09ABZ (STMicroelectronics)	MC78L09ACPG (onsemi)	UA78L09ACLP (TI)	UA78L09ACLPE3 (TI)
Output Voltage	9V	9V	9V	9V	9V
Output Current	100mA	100mA	100mA	100mA	100mA
Input Voltage (Max)	35V	30V	30V	24V	24V
Quiescent Current	2 mA	5.5 mA	6 mA	Not specified	Not specified
PSRR (120Hz)	44dB	44dB	57dB	45dB	45dB
Protection Features	Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Temperature, Short Circuit	Over Current, Over Temperature, Reverse Polarity, Short Circuit	Over Current, Over Temperature, Reverse Polarity, Short Circuit
Operating Temperature	0°C ~ 125°C	-40°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C
Package	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3
Product Status	Obsolete	Active	Active	Last Time Buy	Last Time Buy
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For applications currently using the LM78L09ACZ, the following selection criteria apply:

L78L09ABZ (STMicroelectronics) is the preferred substitute for new designs and production continuity. This part maintains active product status, ensuring long-term availability. It provides extended operating temperature range (-40°C to 125°C) and includes over-current protection in addition to over-temperature and short-circuit protection. The maximum input voltage of 30V is suitable for most applications within the original 35V specification margin.

MC78L09ACPG (onsemi) offers active product status with superior PSRR performance (57dB versus 44dB), beneficial for noise-sensitive applications. Maximum input voltage is 30V. This part is suitable for direct replacement in existing designs.

UA78L09ACLP and UA78L09ACLPE3 (Texas Instruments) maintain Texas Instruments sourcing continuity and include comprehensive protection features (over-current, over-temperature, reverse-polarity, and short-circuit). Both are listed as last-time-buy status. The UA78L09ACLPE3 variant offers higher inventory availability (4537 pcs) compared to UA78L09ACLP (1330 pcs). Maximum input voltage is limited to 24V, requiring verification in applications exceeding this threshold.

All substitute parts are ROHS3 compliant and REACH unaffected, maintaining regulatory compliance equivalent to the original LM78L09ACZ.

Frequently Asked Questions (FAQ)

Q: Can the L78L09ABZ directly replace the LM78L09ACZ in existing PCB designs?

A: Yes. Both parts use identical TO-92-3 through-hole packaging and pinout. The L78L09ABZ maintains the same 9V fixed output and 100mA current rating. Pin-for-pin compatibility is confirmed.

Q: What is the impact of the lower maximum input voltage (30V) in substitute parts compared to the original 35V specification?

A: The L78L09ABZ, MC78L09ACPG, and UA78L09ACLP/ACLPE3 all support 30V or 24V maximum input. Applications operating below these thresholds experience no functional impact. Designs requiring input voltages between 30V and 35V must use the original LM78L09ACZ or verify alternative topologies.

Q: Which substitute part offers the best long-term availability?

A: L78L09ABZ (STMicroelectronics) and MC78L09ACPG (onsemi) both maintain active product status. The UA78L09ACLP and UA78L09ACLPE3 are designated last-time-buy, indicating limited future availability.

Q: Are there differences in quiescent current consumption between the main part and substitutes?

A: The LM78L09ACZ specifies 2 mA quiescent current. The L78L09ABZ and MC78L09ACPG specify 5.5 mA and 6 mA respectively. For battery-powered or low-power standby applications, this difference may be significant. The UA78L09ACLP and UA78L09ACLPE3 do not specify quiescent current in the provided data.

Q: What additional protection features do substitute parts provide?

A: The L78L09ABZ adds over-current protection. The UA78L09ACLP and UA78L09ACLPE3 add both over-current and reverse-polarity protection. These enhancements improve circuit robustness without affecting normal operation.

Q: Is the extended temperature range (-40°C to 125°C) of the L78L09ABZ beneficial for my application?

A: The extended lower temperature limit of -40°C applies only to applications operating below 0°C. Standard industrial applications operating within 0°C to 125°C experience no functional difference.

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