![]() LD1117S33TR device package |
![]() LD1117S33TR schematic symbol |
Almost all modern digital electronic devices require low level DC voltages for their operation. This low DC voltage allows these electronics systems to be battery-powered, portable, lightweight and safe. The typical power supply voltage range for such devices is 3.3V to 5V. Many digital electronic devices require AC mains power supply for charging or direct powering up. In such cases rectifier circuits are required to convert the AC power to DC power. These rectifier circuits use diodes, capacitors and voltage regulators to provide low level DC voltage to the electronic components. When a diode bridge converts the AC voltage to DC voltage, the output voltage contains high ripple content which degrades power quality. Capacitors along with voltage regulators are used in such circuits to remove the ripple and provide a stable DC voltage to the electronic load such as microprocessors or LCDs.
What is LD1117S33TR?
The LD1117S33TR is a low voltage drop regulator manufactured by ST Microelectronics. This regulator is capable of providing a maximum current of 1300mA to the load. The output voltage of the regulator is 3.3VDC. This regulator has a compact size with excellent thermal characteristics. The built in NPN pass transistor ensures high efficiency. Other than 1 or 2 capacitors, the device does not need any other external components. The device is packaged in an SOT-223 compact package.
Pin Configuration
The pin configuration of the LD1117S33TR linear voltage regulator is given in the table below:
Pin name | Pin description |
Common | Ground pin |
Input | Supply input |
Output | Voltage output |
Features
- 3 terminal device
- Stable 3.3V DC output
- 1V low drop voltage
- Output current up to 800mA
- Availability of adjustable version
- Supply voltage rejection of 75dB
- Positive output configuration
- Over current protection
- Over heat protection
- NPN pass transistor
Applications
The applications of LD1117S33TR voltage regulator are provided as following:
- Voltage regulation in handheld devices
- Computer and server power supplies
- Power supplies in telecommunication equipment
- Power supplies in digital and embedded systems
Specifications
The major technical specifications of the LD1117S33TR are provided as following:
- Terminals: 3
- Max DC input voltage: 15V
- Max power dissipation: 12W
- Max operating junction temperature: 125OC
- Output voltage: 3.3V
- Max output current: 1.3A
- Typical line regulation: 1mV
- Typical load regulation: 1mV
- Supply voltage rejection: 75dB
- Package: SOT-223
Alternatives
PAM3110ABA330R, AME8810AEGTZ, SC1202CST-3.3;
How LD1117S33TR work?
The LD1117S33TR is a general-purpose low-drop voltage regulator which is widely used in power supply circuits. One of the most common LD1117 based circuit is the full wave diode rectifier power supply. In this power supply, the first stage is a power transformer which steps down 220/120VAC to 3.3VAC. The 2nd circuit stage is the diode rectifier which converts the 3.3VAC to 3.3VDC. The 3rd stage in the circuit is the LD1117 regulator which removes the ripple from the converted DC voltage and provides a stable DC voltage at the output.
The application circuit of such a power supply is given in the figure below:
![LD1117S33TR application circuit](https://www.win-source.net/blog/wp-content/uploads/2019/09/LD1117S33TR-application-circuit-400x134.jpg)
LD1117S33TR application circuit
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