TL494 IDR Detailed explanation of pin function specifications and circuit principle instructions

The TL494IDR is a PWM (Pulse Width Modulation) Controller integrated circuit designed primarily for applications in power supplies. It is part of the TL494 family of ICs produced by Texas Instruments.

Package Type:

The TL494IDR comes in a DIP-16 package (Dual In-line Package), which means it has 16 pins in total.

Pin Function Specifications:

Here’s the detailed explanation of the 16 pins in the TL494IDR package:

Pin Number Pin Name Pin Function 1 Vcc Positive supply voltage input (Typically +12V to +40V) 2 Vref Voltage reference output (5V ±2%) for external components 3 Inverting Input Inverting input of the internal error amplifier (for feedback from the system) 4 Non-inverting Input Non-inverting input of the error amplifier (for feedback input) 5 Error Amplifier Output Output of the error amplifier, connected to the PWM comparator 6 Output 1 Pulse width modulated output (drives external power transistor ) 7 Output 2 Pulse width modulated output (drives external power transistor) 8 Ground Ground connection for the IC (typically 0V) 9 External Timing capacitor External capacitor for setting the oscillator frequency 10 Timing Resistor External resistor to set the oscillator frequency along with timing capacitor 11 Feedback Input Feedback input pin for adjusting duty cycle based on external circuit 12 Shutdown Shutdown control input (when high, the IC goes into a low-power state) 13 Control Voltage Input Control input for external voltage reference to modulate duty cycle 14 Feedback Resistor Resistor from external source used to modify feedback to control the duty cycle 15 Collector of Output Transistor Collector pin to drive the power transistor (usually for push-pull circuits) 16 Base of Output Transistor Base drive to external power transistor, responsible for switching operation

Circuit Principle Instructions:

The TL494IDR is a PWM controller designed to generate a square wave signal that controls the duty cycle of the power transistors (e.g., MOSFETs , IGBTs) in a power supply or inverter system.

The main functions are as follows:

The error amplifier compares the feedback voltage from the system to a reference voltage. The error signal determines the pulse width of the output signal. Pin 9 (Timing Capacitor) and Pin 10 (Timing Resistor) control the frequency of the oscillator in the TL494, which sets the switching frequency of the power transistors. Output pins 6 and 7 drive the external transistors. These are typically connected to a power transistor's base or gate (depending on the transistor type), controlling the flow of current to the load. The feedback mechanism ensures the output maintains the desired voltage or current.

FAQs for TL494IDR:

1. Q: What is the function of Pin 1 (Vcc) in TL494IDR? A: Pin 1 (Vcc) is the power supply input pin, providing the necessary voltage (typically 12V to 40V) for the operation of the TL494IDR.

2. Q: What is the function of Pin 8 (Ground)? A: Pin 8 (Ground) is the reference ground pin, providing the common return path for the IC's internal circuitry.

3. Q: How does Pin 2 (Vref) function? A: Pin 2 (Vref) provides a stable 5V reference output for external components to use, such as for generating reference voltages or controlling other circuits.

4. Q: How do Pins 3 and 4 (Inverting and Non-inverting Inputs) work in the TL494IDR? A: Pins 3 and 4 are used to provide feedback to the error amplifier. Pin 3 is for the inverting input, and Pin 4 is for the non-inverting input. The feedback voltage is compared to a reference voltage to determine the duty cycle of the PWM output.

5. Q: What is the role of Pin 5 (Error Amplifier Output)? A: Pin 5 is the output of the error amplifier. The output voltage here controls the duty cycle of the PWM signals generated at Pins 6 and 7.

6. Q: What are the functions of Pins 6 and 7 (Output 1 and Output 2)? A: Pins 6 and 7 provide the pulse width modulated (PWM) output signals that drive external transistors or other switching devices in the power supply circuit.

7. Q: What is Pin 9 (External Timing Capacitor) used for? A: Pin 9 is connected to an external timing capacitor that works with Pin 10 (Timing Resistor) to set the frequency of the internal oscillator in the TL494.

8. Q: How does the feedback mechanism work on Pin 11 (Feedback Input)? A: Pin 11 is the feedback input. The duty cycle can be adjusted by applying a feedback voltage, which is often derived from the output of the power supply being regulated.

9. Q: What is the purpose of Pin 12 (Shutdown)? A: Pin 12 is used to shut down the TL494 by applying a high voltage. When it is high, the IC stops generating output signals, effectively putting the circuit in a low-power state.

10. Q: How does Pin 13 (Control Voltage Input) work? A: Pin 13 is used for modulating the PWM duty cycle based on an external control voltage, which allows for dynamic control of the output power.

11. Q: What is the function of Pin 14 (Feedback Resistor)? A: Pin 14 is connected to an external resistor that helps modify the feedback signal, which in turn affects the duty cycle of the output PWM signal.

12. Q: How is Pin 15 (Collector of Output Transistor) used in the circuit? A: Pin 15 connects to the collector of the external output transistor, enabling it to switch on and off according to the PWM signal generated by the TL494.

13. Q: What is the function of Pin 16 (Base of Output Transistor)? A: Pin 16 provides base drive for the external output transistor, controlling the switching behavior of the transistor in response to the PWM signal.

14. Q: Can the TL494IDR be used for both DC and AC applications? A: Yes, the TL494IDR can be used in both DC and AC applications, including DC-DC and AC-DC conversion, depending on the circuit design.

15. Q: What is the typical frequency range for TL494IDR? A: The typical frequency range of the TL494IDR is from 25 kHz to 500 kHz, depending on the external timing components (resistor and capacitor).

16. Q: What type of power transistors can be used with TL494IDR? A: The TL494IDR can drive a variety of power transistors, including MOSFETs, IGBTs, and bipolar junction transistors (BJTs).

17. Q: How is the duty cycle of the PWM output controlled? A: The duty cycle is controlled by adjusting the feedback voltage applied to Pins 3, 4, and 11, which is compared with the internal reference voltage.

18. Q: What happens if Pin 12 (Shutdown) is not used? A: If Pin 12 is left floating or unconnected, the TL494IDR will not enter the shutdown state and will continue to operate normally.

19. Q: What is the typical application for TL494IDR? A: The TL494IDR is commonly used in power supply circuits, such as switch-mode power supplies (SMPS), inverter circuits, and motor control applications.

20. Q: Can the TL494IDR be used for overcurrent protection? A: Yes, the TL494IDR can be configured with external components to provide overcurrent protection by adjusting the feedback and controlling the duty cycle in response to load conditions.

Conclusion:

The TL494IDR is a highly versatile PWM controller with a broad range of applications in power supply designs. The detailed pin function and FAQs should provide a clear understanding of how each pin works and how the IC is utilized in various circuits.