Build with LD1117-3.3 — Datasheet Specs & AI Design Help

00 — Overview

What the LD1117-3.3 does

The LD1117x family comprises low dropout, 3-terminal positive voltage regulators available in fixed output versions from 1.2V to 5.0V plus an adjustable variant. These devices deliver up to 800mA or 1A depending on the current code, featuring a low dropout voltage and built-in current limit with over temperature protection. The parts support MLCCs and are suitable for SCSI-2 active termination when configured for 2.85V. Engineers typically use them to provide stable power rails in compact designs requiring high efficiency and robust thermal performance across various package types including SOT-223, SOT-89, and TO-220.

Next step

Start building with LD1117-3.3 → 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 LD1117-3.3
Parameter	Min	Typ	Max	Conditions	Source
quiescent current	—	5 mA	10 mA	VIN≤10V; For LD1117/A-1.2	Unisonic datasheet, p. 5 — For LD1117/A-1.2
output voltage	1.18 V	1.2 V	1.22 V	VIN = 3.2V, IOUT = 10mA, TJ = 25°C; For LD1117/A-1.2	Unisonic datasheet, p. 5 — For LD1117/A-1.2
output current	—	800 mA	—		Unisonic datasheet, p. 1
supply voltage range	—	—	18 V	BLOCK DIAGRAM	Unisonic datasheet, p. 4 — BLOCK DIAGRAM
operating temperature	-20 °C	—	125 °C	(note 2); BLOCK DIAGRAM	Unisonic datasheet, p. 4 — BLOCK DIAGRAM
psrr	60 dB	75 dB	—	IOUT = 40mA, f = 120Hz, TJ = 25°C, VIN = 4.2V, VRIPPLE = 1VPP; For LD1117/A-1.2	Unisonic datasheet, p. 5 — For LD1117/A-1.2
dropout voltage	—	1 V	1.1 V	IOUT = 100mA; For LD1117/A-1.2	Unisonic datasheet, p. 5 — For LD1117/A-1.2
output noise voltage	—	100 µV	—	B = 10Hz to 10KHz, TJ = 25°C; For LD1117/A-1.2	Unisonic datasheet, p. 5 — For LD1117/A-1.2
output count	—	1	—		Unisonic datasheet, p. 5 — For LD1117/A-1.2

02 — Alternatives

Closest matches to LD1117-3.3

AZ1117-5.0 4.2× higher output voltage, 1.5× higher output noise voltage, 1.2× higher output current

L7805AB 10.0× lower output noise voltage, 4.2× higher output voltage, 2.0× higher dropout voltage

L78L05ABD13TR 12.5× higher output voltage, 8.0× lower output current, 1.9× lower psrr

L78M05ABDT 4.2× higher output voltage, 2.5× lower output noise voltage, 2.0× higher dropout voltage

L78M05ABV 4.2× higher output voltage, 2.5× lower output noise voltage, 2.0× higher dropout voltage

AMS1117-3.3 1.5× lower supply voltage range, 1.2× higher output current, 1.2× lower operating temperature

AZ1117C-3.3 2.8× higher output voltage, 1.2× higher output current, 1.2× lower quiescent current

AP2112 4.2× lower supply voltage range, 2.3× lower operating temperature, 2.0× lower output noise voltage

03 — FAQ

Frequently asked questions

What is the dropout voltage for the LD1117/A-1.2 when IOUT = 100mA?

The dropout voltage is 1 V.

What is the maximum operating temperature for the LD1117-3.3 under the conditions specified in note 2 and the block diagram?

The operating temperature is 125 °C (note 2); BLOCK DIAGRAM.

What is the output count for the LD1117-3.3?

The output count is 1.

What is the maximum output current?

The maximum output current is 800 mA.

What is the output noise voltage for the LD1117-3.3?

The output noise voltage is 100 µV at B = 10Hz to 10KHz and TJ = 25°C.

What is the output voltage for the LD1117/A-1.2 when VIN = 3.2V, IOUT = 10mA, and TJ = 25°C?

The output voltage is 1.2 V.

What is the PSRR of the LD1117-3.3 at IOUT = 40mA, f = 120Hz, TJ = 25°C, VIN = 4.2V, and VRIPPLE = 1VPP?

The PSRR is 75 dB.

What is the quiescent current for the LD1117/A-1.2 when VIN≤10V?

The quiescent current is 5 mA.

What is the supply voltage range for the LD1117-3.3 as shown in the block diagram?

The supply voltage range is 18 V.