Build with L78L05 — Datasheet Specs & AI Design Help

00 — Overview

What the L78L05 does

The L78L series are three-terminal positive voltage regulators offering fixed output voltages from 3.3 V to 24 V in 5 V, 6 V, 8 V, 9 V, 10 V, 12 V, and 15 V options. These devices support output currents up to 100 mA and feature internal current limiting, thermal shutdown, and short-circuit protection. Available in A and C tolerance grades, they require no external components for basic operation. Engineers typically use them for local on-card regulation to eliminate noise and distribution problems. The series also serves as a replacement for Zener diode and resistor combinations, providing lower quiescent current and reduced noise while remaining essentially indestructible with adequate heat sinking.

Next step

Start building with L78L05 → Every number above is cited straight from the datasheet — ask what they mean for your design, and the assistant answers from the same source documents.

01 — Key specifications

Datasheet parameters

Datasheet parameters for L78L05
Parameter	Min	Typ	Max	Conditions	Source
quiescent current	—	—	6 mA	TJ = 25 °C; id	ST datasheet, p. 6 — Table 3: Electrical characteristics of L78L33C
output voltage	13.8 V	15 V	16.2 V	TJ = 25 °C; vo	ST datasheet, p. 12 — Table 9: Electrical characteristics of L78L15C
output current (abs max)	—	—	100 mA	io; Absolute maximum ratings	ST datasheet, p. 5 — Table 1: Absolute maximum ratings
supply voltage range	7 V	—	20 V		ST datasheet, p. 16 — Table 13: Electrical characteristics of L78L05AB and L78L05AC
operating temperature (abs max)	-40 °C	—	125 °C		ST datasheet, p. 5 — Table 1: Absolute maximum ratings
psrr	33 dB	39 dB	—	VI = 18.5 to 28.5 V, f = 120 HzIo = 40 mA, TJ = 25 °C	ST datasheet, p. 12 — Table 9: Electrical characteristics of L78L15C
dropout voltage	—	1.7 V	—	vd	ST datasheet, p. 12 — Table 9: Electrical characteristics of L78L15C
output noise voltage	—	90 µV	—	B = 10 Hz to 100 kHz, TJ = 25 °C; en	ST datasheet, p. 12 — Table 9: Electrical characteristics of L78L15C
output count	—	1	—		ST datasheet, p. 1

02 — Alternatives

Closest matches to L78L05

AZ1117-5.0 10.0× higher output current, 3.0× lower output voltage, 1.9× higher psrr

L78L05AB 3.0× lower output voltage, 2.2× lower output noise voltage, 1.3× higher psrr

LD1117-3.3 12.5× lower output voltage, 8.0× higher output current, 1.9× higher psrr

78L05 3.0× lower quiescent current, 1.9× lower operating temperature, 1.2× lower output voltage

L78M05ABV 5.0× higher output current, 3.0× lower output voltage, 2.2× lower output noise voltage

AMS1117-3.3 10.0× higher output current, 1.9× higher psrr, 1.7× lower dropout voltage

AZ1117C-3.3 10.0× higher output current, 4.5× lower output voltage, 1.8× higher psrr

CJ78L05 3.0× lower output voltage, 2.1× lower output noise voltage, 1.6× lower quiescent current

03 — FAQ

Frequently asked questions

What is the dropout voltage at vd?

The dropout voltage at vd is 1.7 V.

What is the maximum operating temperature?

The maximum operating temperature is 125 °C.

What is the output count for the L78L05ABD13TR?

The output count is 1.

What is the absolute maximum output current (io) for the L78L05ABD13TR?

The absolute maximum output current (io) is 100 mA.

What is the output noise voltage of the L78L05ABD13TR?

The output noise voltage is 90 µV when B = 10 Hz to 100 kHz and TJ = 25 °C.

What is the output voltage when TJ = 25 °C and vo?

The output voltage is 15 V.

What is the Power Supply Rejection Ratio (PSRR) of the L78L05ABD13TR?

The PSRR is 39 dB when VI = 18.5 to 28.5 V, f = 120 Hz, Io = 40 mA, and TJ = 25 °C.

What is the quiescent current at TJ = 25 °C?

The quiescent current is 6 mA at TJ = 25 °C.

What is the supply voltage range for the L78L05ABD13TR?

The supply voltage range is 20 V.