Almost all modern digital electronic devices require low level DC voltages for their functioning. This low DC voltage allows these electronics devices to be battery-powered, portable, lightweight and safe. The typical power supply voltage range for these devices is 3.3V to 5V. Many digital electronic devices require AC mains power supply for charging or direct power 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 and voltage regulators are used in such power conversion circuits to eliminate the ripple and output a stable DC voltage to the electronic load such as microprocessors or TFTs.
What is NCP1117ST50T3G?
The NCP1117ST50T3G is a low dropout positive voltage regulator manufactured by ON Semiconductor. The NCP1117ST50T3G is capable of providing an output current in excess of 1.0A whereas the maximum dropout voltage is 1.2V. The output voltage is 5V stable DC. The salient features of this device include safe operating area compensation, thermal shutdown, and output current limiter. The device package is Lead free SOT-223.
Pin Configuration
The pin configuration of the NCP1117ST50T3G 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 5.0V DC output
- Maximum dropout voltage of 1.2V
- Output current in excess of 1.0A
- No minimum load requirement
- Current limiter and thermal shutdown features
- Lead free packaging
- Positive output configuration
Applications
The applications of NCP1117ST50T3G are provided as following:
- Consumer and industrial equipment point of regulation
- Switching power supply post regulation
- Computer hard drive controllers
- Battery chargers
- Server power supplies
- Power supplies in embedded hardware systems
Specifications
The major technical specifications of the NCP1117ST50T3G are provided as following:
- Terminals: 3
- Max DC input voltage: 20V
- Max power dissipation: 15W
- Max operating junction temperature: 125OC
- Output voltage: 5V
- Max output current: 1.0A+
- Ripple rejection: 64dB
- Package: Lead free SOT-223
How NCP1117ST50T3G work?
The NCP1117ST50T3G is a low-drop positive voltage regulator which is widely used in switching power supply circuits to get fixed and stable 5V output. One of the most common NCP1117ST50T3G 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 5VAC. The 2nd circuit stage is the diode rectifier which converts the 5VAC to 5VDC. 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:
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