Infineon BSP170PH6327: Key Features and Application Circuit Design
The Infineon BSP170PH6327 is a robust p-channel enhancement mode Power MOSFET housed in a compact SOT-223 package. Engineered for efficiency and reliability, this component is a cornerstone in modern power management and switching applications, particularly where space-saving and high performance are paramount.
Key Features
The defining characteristics of the BSP170PH6327 make it an excellent choice for designers. Its most prominent feature is its extremely low threshold voltage (VGS(th)), typically -1V. This allows for seamless operation and direct control from low-voltage microcontroller GPIO pins (e.g., 3.3V or 5V), eliminating the need for complex level-shifting circuits. Furthermore, it boasts a low on-state resistance (RDS(on)) of just 160 mΩ at a gate-source voltage of -4.5V. This low resistance minimizes conduction losses, leading to higher efficiency and reduced heat generation during operation.
The device is designed to handle a continuous drain current (ID) of -1.7A and features a drain-source voltage (VDSS) of -60V, making it suitable for a wide range of low-to-medium power applications. Its avalanche ruggedness ensures it can withstand unexpected voltage spikes, enhancing the overall robustness of the end product.
Application Circuit Design: A Low-Side Switch
A fundamental and highly common application for this p-channel MOSFET is as a low-side switch to control a load connected to a higher voltage rail (e.g., 12V). The primary design challenge with a p-channel MOSFET is that it requires a negative VGS to turn on. The following circuit and explanation detail a standard implementation.
Circuit Components:
Vdd: Main supply voltage (e.g., 12V)
Load: The device to be controlled (e.g., a motor, solenoid, or LED strip)
MCU: Microcontroller (e.g., operating at 3.3V)
Q1: Infineon BSP170PH6327
R1: Pull-up resistor (10kΩ)
R2: Gate series resistor (100Ω)
Circuit Operation:
1. Default State (MCU pin = HIGH/3.3V): When the microcontroller's GPIO pin is set to a logic high (3.3V), the voltage difference between the gate (G) and the source (S) is VGS = 3.3V - 12V = -8.7V. This exceeds the threshold voltage, keeping the MOSFET firmly turned OFF. The pull-up resistor R1 ensures the gate is pulled to the source voltage when the MCU pin is in a high-impedance state, preventing false triggering.
2. Active State (MCU pin = LOW/0V): When the microcontroller pin is set to a logic low (0V), the gate is pulled to 0V. The VGS becomes 0V - 12V = -12V. This large negative voltage fully enhances the MOSFET, turning it ON and creating a low-resistance path between the source and drain. This allows current to flow from Vdd, through the load, through the MOSFET, and to ground, thereby powering the load.
Design Considerations:
Gate Resistor (R2): This resistor is crucial for damping high-frequency oscillations that can occur during the fast switching transitions of the MOSFET. It improves EMI performance and overall circuit stability.
Load Type: For inductive loads like motors or relays, a flyback diode must be placed in reverse bias across the load to protect the MOSFET from voltage spikes generated when the current is suddenly interrupted.
Heat Dissipation: While the RDS(on) is low, at maximum current, power dissipation (P = I² RDS(on)) can still generate heat. For continuous operation near the current limit, adequate PCB copper or a small heatsink is recommended.
The Infineon BSP170PH6327 stands out as an exceptionally versatile and efficient solution for power switching tasks controlled by low-voltage logic. Its combination of low threshold voltage, low on-resistance, and high robustness in a small form factor makes it an ideal choice for a vast array of applications, including DC-DC converters, load switching, power management in portable devices, and motor control. Its simple driver requirements significantly simplify circuit design, reducing both component count and board space.
Keywords:
P-Channel MOSFET
Low-Side Switch
Low Threshold Voltage
Low On-Resistance
Power Management
