The MSN4688A, offered by HeroMicro, is a highly integrated 30V N+P Channel Dual MOSFET. It integrates one N-channel and one P-channel power MOSFET into a single, compact SOP-8D surface-mount package. Utilizing advanced high-cell-density Trench technology, this device achieves an excellent combination of ultra-low on-resistance (RDS(ON)) and low gate charge (Qg), making it an ideal choice for building H-bridge motor drivers, load switches, power management circuits, and battery protection systems.
1. Key Features Overview
Based on the datasheet provided by HeroMicro (MSN4688A.pdf), key specifications are:
Integrated N+P Design:
N-Channel: VDS = +30V, ID = +6.3A (TA=25°C), RDS(ON) < 24mΩ (@ VGS=10V)
P-Channel: VDS = -30V, ID = -6A (TA=25°C), RDS(ON) < 40mΩ (@ VGS=-10V)
Outstanding Performance:
Ultra-Low On-Resistance: Stands out among SOP-8 packaged products, significantly reducing conduction losses and heat generation.
Low Gate Charge: Enables fast switching, reduces switching losses, and improves system efficiency.
High Reliability:
Wide Operating Junction Temperature Range: -55°C to +150°C.
Power Dissipation: 2.7W for N-channel, 2.15W for P-channel (TA=25°C).
Eco-Friendly & Package:
Green Device: Compliant with RoHS and other environmental standards.
Package: SOP-8D, an 8-pin small outline package with an Exposed Pad (EP). Soldering this pad to the PCB dramatically improves thermal performance.
2. Pin Configuration & Internal Circuit
The MSN4688A uses an SOP-8D package with the following pinout and internal circuit:
| Pin | Symbol | Function |
|---|---|---|
| 1 | G1 | Gate of N-Channel MOSFET |
| 2 | S1 | Source of N-Channel MOSFET |
| 3 | D1 | Drain of N-Channel MOSFET |
| 4 | D1 | Drain of N-Channel MOSFET - Internally connected to Pin 3 |
| 5 | D2 | Drain of P-Channel MOSFET |
| 6 | D2 | Drain of P-Channel MOSFET - Internally connected to Pin 5 |
| 7 | S2 | Source of P-Channel MOSFET |
| 8 | G2 | Gate of P-Channel MOSFET |
| EP | EP | Exposed Pad - Typically connected to all Drains (D1/D2) |
Critical Notes:
The Exposed Pad (EP) is the common connection point for all MOSFET drains (D1 & D2). In PCB design, this pad must be soldered to a large copper pour. This serves not only as an electrical connection (often used as power ground or bus voltage) but is also the primary thermal path. Neglecting this will cause severe overheating.
3. Critical Design Guidelines
(1) Typical Application: H-Bridge / Half-Bridge DriverThe most common application for the MSN4688A is to form a Half-Bridge or, in conjunction with another device, a Full H-Bridge to drive DC motors or inductive loads.
Half-Bridge Connection Example:
Connect the P-channel Source (S2) to the positive supply rail (VCC, e.g., +12V).
Connect the N-channel Source (S1) to Ground (GND).
Connect the Drains of both P and N channels (D1/D2/EP) together to form the Output Node (OUT), which connects to one terminal of the motor.
Complementary Drive: The control signals must ensure that the P-channel and N-channel are never ON simultaneously (to avoid "shoot-through"). A dead time is typically inserted between switching transitions.
(2) Gate Drive Logic
N-Channel MOSFET: Turns ON when G1 is at a high voltage (e.g., 10V) relative to S1 (GND).
P-Channel MOSFET: Turns ON when G2 is at a low voltage (e.g., GND) relative to S2 (VCC). Since the P-channel is used as a high-side switch, its gate drive signal often requires a level shifter or a driver capable of withstanding the VCC voltage.
(3) PCB Layout & Thermal Management (Critical!)
Exposed Pad Handling: This is paramount. A large copper pour must be designed on both the top and bottom layers of the PCB for the EP pad, connected to inner-layer power/ground planes with multiple vias. This directly determines the maximum current the device can safely handle.
Minimize Power Loop: The entire power loop—from VCC to the P-channel source (S2), to the output (OUT), through the load, back to ground (GND), and to the N-channel source (S1)—should be short and wide to minimize parasitic inductance.
Drive Signal Routing: Route gate drive traces away from high dv/dt power traces to prevent noise coupling and false triggering.
(4) Absolute Maximum Ratings
Gate-Source Voltage (VGS): ±20V (applies to both N and P channels). Exceeding this can cause permanent gate oxide breakdown.
4. Typical Applications
Small DC motor drives in portable devices (e.g., toys, electric toothbrushes, fans)
Load switches and reverse battery protection in battery-powered systems
Synchronous rectification stages in DC-DC converters
Output stages in audio amplifiers
Any application requiring a complementary MOSFET pair in a single, space-saving package
5. Summary
HeroMicro's MSN4688A offers designers an efficient and space-saving power switching solution thanks to its integrated N+P channels, ultra-low RDS(ON), and SOP-8D package with an exposed thermal pad. The keys to successful implementation are correctly understanding the drive logic for N/P channels, carefully designing the complementary drive timing to prevent shoot-through, and providing ample thermal relief for the exposed pad on the PCB. By following this guide, you can fully leverage the performance of this dual MOSFET to build reliable and efficient power electronic systems.
