TNY279PN Detailed explanation of pin function specifications and circuit principle instructions
The TNY279PN is a part of the TinySwitch family of integrated circuits from Power Integrations. This family of ICs is commonly used in low-power switch-mode power supplies (SMPS) and is designed for flyback converters. Below is a detailed explanation of the pin functions, pin configuration, and an in-depth look at the IC’s principles of operation, based on the specifications available for the TNY279PN.
Pin Function Specifications and Circuit Principle Instructions for TNY279PN
1. Package Type: The TNY279PN is housed in a DIP-8 (Dual In-line Package with 8 pins) package. 2. Pinout Configuration and Pin Function List (All 8 Pins): Pin No. Pin Name Pin Function Description 1 VDD Power Supply Pin: Provides power to the internal circuitry of the IC. Connect this pin to the positive supply voltage (typically 8 to 30V). A bypass capacitor is typically placed between VDD and ground to filter noise. 2 Drain (D) Drain Pin: This is the power switching pin. The internal power transistor of the IC is connected to this pin. This pin is used for driving the transformer primary winding in flyback converters. It is also the pin where the energy is stored during the off-time of the switch. 3 Source (S) Source Pin: This pin is connected to ground or the negative side of the power supply. It is the return path for the current that flows through the switch during its on-time. 4 GND Ground Pin: This pin serves as the common ground reference for the IC. It is essential for the IC's proper operation and should be connected to the negative terminal of the power supply. 5 Feedback (FB) Feedback Pin: This pin is used to receive the feedback signal from the secondary side of the transformer (typically via an optocoupler in isolated designs). The feedback regulates the output voltage and controls the duty cycle of the power switch to maintain a constant output. 6 NC No Connection Pin: This pin does not connect to any internal circuitry in the IC. It is either left floating or tied to ground, depending on the design. 7 VDD Power Supply Pin: This is another pin that connects to the power supply and is used to power the internal circuits of the IC. The power supply voltage typically ranges between 8V to 30V. 8 Vdd Power Supply Pin: This pin is similar to pin 7 and is used as a power input for the IC's internal operations. It is typically connected to the positive terminal of the power supply and should be decoupled with a capacitor to reduce noise.Circuit Principle
The TNY279PN is designed to work as a flyback converter in low-power applications. The IC integrates a high-voltage power switch with a control circuit to implement the flyback converter topology. The key operating principle is that energy is stored in the transformer during the on-time of the switch and released during the off-time to the output. The feedback loop adjusts the duty cycle of the switch to regulate the output voltage.
FAQs for the TNY279PN
Here is a detailed FAQ based on the TNY279PN model, addressing common queries:
Q: What is the typical application of the TNY279PN? A: The TNY279PN is typically used in low-power flyback converters, such as in adapter circuits, low-power offline power supplies, and isolated power supplies for consumer electronics.
Q: What is the input voltage range for the TNY279PN? A: The typical input voltage range for the TNY279PN is between 8V and 30V, depending on the application.
Q: How many pins does the TNY279PN have? A: The TNY279PN has 8 pins in its DIP-8 package.
Q: Can I use the TNY279PN in non-isolated designs? A: The TNY279PN is generally used in isolated flyback converter designs, but it can also be used in non-isolated designs depending on the application.
Q: What is the purpose of the feedback pin (Pin 5)? A: The feedback pin (Pin 5) is used to regulate the output voltage by controlling the duty cycle of the internal switch. Feedback is typically provided by an optocoupler in isolated designs.
Q: How do I connect the VDD pins (Pin 1, 7, 8)? A: The VDD pins (Pin 1, 7, 8) are all connected to the positive supply voltage (typically 8V to 30V). Decoupling capacitors are placed close to these pins to filter noise.
Q: What is the function of the drain pin (Pin 2)? A: The drain pin (Pin 2) is where the energy from the primary winding of the transformer is stored. It is also connected to the internal power transistor to control the switching of the converter.
Q: Can I use the TNY279PN in high-power applications? A: The TNY279PN is designed for low-power applications, typically up to 30W. For higher-power applications, consider using a higher power-rated IC from the TinySwitch series.
Q: What is the maximum output power of the TNY279PN? A: The TNY279PN can typically support output power up to 30W, depending on the application and the design.
Q: Is thermal management important when using the TNY279PN? A: Yes, thermal management is important for the TNY279PN, especially in high-efficiency designs. Ensure proper heat sinking or PCB design to dissipate heat.
Q: What type of transformer should be used with the TNY279PN? A: The TNY279PN is typically used with a flyback transformer, designed for low-power applications, and optimized for efficiency.
Q: Can I use the TNY279PN for step-up converters? A: The TNY279PN is primarily designed for step-down (buck) or isolated flyback converters, not for step-up (boost) applications.
Q: What is the switching frequency of the TNY279PN? A: The switching frequency of the TNY279PN is typically between 100 kHz and 130 kHz.
Q: How do I connect the ground pin (Pin 4)? A: The ground pin (Pin 4) should be connected to the negative terminal of the power supply or the system ground.
Q: Is the TNY279PN internally protected? A: Yes, the TNY279PN includes internal protections such as over-temperature, over-voltage, and over-current protection.
Q: What is the efficiency of a power supply using the TNY279PN? A: The efficiency depends on the design and the load, but typically, a power supply using the TNY279PN can achieve efficiencies of 70% or higher.
Q: Can the TNY279PN be used in dimming applications? A: The TNY279PN is typically not used in dimming applications; it is designed for power conversion in standard low-power supplies.
Q: What are the output voltage ranges for the TNY279PN? A: The output voltage depends on the transformer turns ratio and the feedback configuration, but typical designs have output voltages ranging from 5V to 15V.
Q: Is there any special PCB layout advice for the TNY279PN? A: For optimal performance, the PCB should minimize parasitic inductance and resistance in the ground and VDD paths. Also, proper decoupling and thermal management are key to reliable operation.
Q: Can I use the TNY279PN in automotive applications? A: Yes, the TNY279PN can be used in automotive applications with proper input voltage protection, as long as the input voltage stays within the specified range of 8V to 30V.
This explanation provides a detailed overview of the TNY279PN, covering the pin functions, usage instructions, and common queries about the IC's operation in practical designs. Let me know if you need further assistance!
