TLP250H: Pinout, Configuration, and Circuit Design

 

The TLP250H is an optocoupler (also known as an optoisolator) designed for gate driving applications, particularly in controlling power transistors like MOSFETs or IGBTs. It combines an infrared LED with a photodetector inside a single package, allowing electrical isolation between the input and output stages. This feature makes it highly useful in high-voltage applications, such as motor drivers, inverters, and power converters.

Key Features of TLP250H:

• Gate Drive Capability: Suitable for driving IGBT and MOSFETs.
• High Output Current: Can drive up to 2.5A peak.
• High-Speed Response: Fast switching times suitable for high-frequency applications.
• Optical Isolation: Electrically isolates the input from the output, providing protection against voltage spikes and noise.
• Compact Package: Available in a DIP-8 package, making it easy to integrate into circuit designs.

TLP250H Pinout

The TLP250H comes in an 8-pin DIP package with the following pin configuration:

Pin Number	Pin Name	Description

 

Pin Description:

1. Pin 1 (Anode): The anode of the LED inside the TLP250H. A current-limiting resistor is typically connected in series with this pin to limit the LED current.
2. Pin 2 (Cathode): The cathode of the LED, connected to the ground of the input circuit.
3. Pin 3 (NC): No connection.
4. Pin 4 (GND): Ground for the output stage. This pin is connected to the common ground of the output circuit, usually linked to the MOSFET or IGBT’s source or emitter.
5. Pin 5 (VCC): Supplies power to the output stage. Typically, this is connected to the positive terminal of a low-voltage power source.
6. Pin 6 (Vout): The output pin of the optocoupler, typically connected to the gate of a MOSFET or IGBT to drive it.
7. Pin 7 (VCC): Power supply for the internal LED. This is usually connected to the same supply voltage used for the logic control circuitry.
8. Pin 8 (VEE): Ground reference for the input circuit.

TLP250H Circuit Configuration

The TLP250H is used for isolating and driving the gate of high-power devices such as MOSFETs or IGBTs in circuits. Here’s an example of a TLP250H gate driver circuit that can be used in motor drivers or inverter circuits.

1. Basic Gate Driver Circuit using TLP250H:

Here is the basic configuration for driving a MOSFET with the TLP250H:

Components Needed:

• TLP250H
• MOSFET (e.g., IRF540N or similar)
• Resistors (e.g., 330Ω, 10kΩ)
• Capacitors (e.g., 0.1µF)
• 12V Power Supply for the MOSFET driver
• Microcontroller or any logic signal source

Circuit Diagram:

+5V | Microcontroller/Logic Signal
|
— (Resistor 330Ω)
|
Pin 1 o—|>|—– Pin 2 (Cathode)
LED
(Anode) |
o
GND
|
|
Pin 7 (VCC)
|
o——————+—-> +5V Logic Power
| |
Pin 5 (VCC) Pin 6 (Output)
| | |
+12V Gate of MOSFET —-(Vout)
|
Source
|
GND

////////////

In this circuit, a microcontroller (or any logic signal source) drives the LED inside the TLP250H. When the LED is forward biased (logic high), the internal transistor conducts and supplies voltage to the gate of the MOSFET, turning it on. When the LED is off (logic low), the MOSFET is turned off.

Key Design Points:

• Current Limiting Resistor: A 330Ω resistor is used to limit the current flowing through the LED inside the TLP250H.
• VCC Capacitor: A small 0.1µF capacitor is placed between VCC and ground to filter out noise.
• Pull-Down Resistor: A 10kΩ pull-down resistor is placed at the gate of the MOSFET to ensure that the MOSFET turns off when no signal is present.

 

Applications of TLP250H:

1. Inverter Circuits: TLP250H is widely used to control MOSFETs or IGBTs in inverter circuits where isolation between the control and power side is essential.
2. Motor Drivers: It is used in motor drivers for applications requiring high-speed switching and isolation, such as brushless DC motors.
3. Power Converters: TLP250H is used in DC-DC or AC-DC converters to switch high-voltage MOSFETs.
4. SMPS (Switch-Mode Power Supplies): It is often integrated into SMPS circuits where isolated gate driving is needed for efficient power conversion.

 

Advantages of Using TLP250H:

• High Isolation Voltage: The TLP250H provides up to 5000V isolation, ensuring safe operation between high and low voltage sides.
• High-Speed Operation: With fast switching times, it supports high-frequency operation, making it ideal for switching power applications.
• Compact Size: Its DIP-8 package allows it to be easily integrated into compact circuit designs.
• High Output Current: Capable of delivering up to 2.5A peak output current to drive large MOSFETs or IGBTs.

 

Conclusion

The TLP250H is an excellent choice for designing isolated gate driver circuits in power electronics applications. Its ability to provide optical isolation between the low-voltage logic signals and high-power switching components ensures both safety and reliability in your circuit designs. With its high-speed switching capability, the TLP250H is well-suited for applications like inverters, motor drivers, and power converters.