The IRF9Z24N, offered by HeroMicro, is a high-performance -60V, -20A P-channel power MOSFET. It utilizes advanced Trench technology to achieve an excellent combination of high voltage rating, low on-resistance (RDS(ON)), and low gate charge (Qg). Packaged in the classic TO-220 through-hole package with an excellent thermal tab, this device is well-suited for use as a high-side switch in power management, load switching, motor control, and various industrial switching applications.
1. Key Features Overview
Based on the datasheet provided (IRF9Z24N.pdf), key specifications are:
High Voltage & Current Rating:
Drain-Source Voltage (VDS): -60V
Continuous Drain Current (ID): -20A (TC=25°C), -13.5A (TC=100°C)
Pulsed Drain Current (IDM): Up to -72A
Excellent Conduction & Switching Performance:
Low On-Resistance (RDS(ON)): Typical 58mΩ, Max 68mΩ (@ VGS=-10V, ID=-9A).
Low Gate Charge (Qg): Typical 82.32nC (@ VGS=-10V, VDS=-30V, ID=-10A), helping to reduce switching losses.
High Reliability & Thermal Performance:
Wide Operating Junction Temperature Range: -55°C to +150°C.
High Power Dissipation: 53W (TC=25°C).
Low Thermal Resistance: Junction-to-Case (RθJC) is 2.36°C/W, ensuring efficient heat transfer to a heatsink.
Package: TO-220, a through-hole package with a large metal tab, which is an industry standard for medium-power applications.
2. Pin Configuration
The IRF9Z24N uses a standard TO-220 three-pin package (viewed from the front with the label facing you):
| Pin | Symbol | Function |
|---|---|---|
| 1 | G | Gate |
| 2 | D | Drain - Large exposed metal tab on back |
| 3 | S | Source |
Critical Notes:
The Drain (D) is internally connected to the large metal tab on the back. During installation, this tab must be mounted to a heatsink using an insulating washer and thermal grease for optimal electrical isolation and thermal management. If the system allows, it can also be soldered directly to a large copper pour on the PCB for cooling.
3. Critical Design Guidelines
(1) P-Channel MOSFET Operation Principle
Turn-On Condition: For a P-channel MOSFET, it turns on when the Gate-to-Source voltage (VGS) is negative and its absolute value is greater than the threshold voltage (VGS(th)). The IRF9Z24N's VGS(th) ranges from -1V to -2.5V.
High-Side Switch Application: P-channel MOSFETs are most commonly used as high-side switches. The Source (S) is connected to the positive supply rail (e.g., +12V), and the Drain (D) is connected to the load. To turn the MOSFET ON, the Gate (G) must be pulled LOW (e.g., to GND), making VGS = 0V - 12V = -12V. To turn it OFF, the Gate must be pulled up to the Source potential (+12V), making VGS = 0V.
(2) Gate Drive Design
Recommended Drive Voltage (VGS): To achieve the lowest RDS(ON) and best efficiency, a -10V drive is strongly recommended (i.e., the gate is 10V lower than the source).
Drive Circuitry: Since P-channel MOSFETs are typically used as high-side switches, their gate drive signal requires a level-shifting circuit or a dedicated high-side driver IC to be controlled by common logic levels (e.g., from a 3.3V/5V MCU). Simple discrete circuits (e.g., using an NPN transistor) can also be used for low-frequency switching applications.
(3) Body Diode Characteristics
An internal body diode is integrated from Drain (D) to Source (S) (due to its P-channel structure).
Forward Voltage (VSD): Max -1.2V (@ ISD=-9A). In inductive load applications (e.g., motors), this diode can serve as a freewheeling path.
(4) PCB Layout & Thermal Management (Critical!)
Drain Tab Handling: This is key to unlocking its 53W dissipation capability. If using a heatsink, always use an insulating kit and thermal grease. For board-level cooling, the PCB must have a large copper pour for the backside drain tab, connected to inner-layer power/ground planes with multiple vias.
Minimize Power Loop: The high-frequency power loop, consisting of input/output capacitors, the MOSFET, and the freewheeling path, should be as short, wide, and direct as possible to minimize parasitic inductance.
(5) Absolute Maximum Ratings
Gate-Source Voltage (VGS): ±20V. Exceeding this can cause permanent gate oxide breakdown.
4. Typical Applications
High-side synchronous rectifier or main switch in DC-DC converters
Load switch and power path control in battery-powered devices
High-side driver in motor H-bridge circuits
General-purpose electronic switches and power management
5. Summary
HeroMicro's IRF9Z24N is a reliable choice for medium-power P-channel switching applications, thanks to its -60V high voltage rating, 68mΩ low on-resistance, and the excellent thermal performance offered by the TO-220 package. The keys to successful implementation are understanding the driving logic of P-channel MOSFETs, designing an appropriate high-side drive circuit, and ensuring proper thermal management. By following this guide, you can ensure this MOSFET operates efficiently and reliably in a wide range of applications.
