MIC4428YM

The MIC4428YM is a high-speed dual MOSFET gate driver from Microchip Technology (originally from Micrel Semiconductor), designed specifically for driving N-channel power MOSFETs and IGBTs in low-side switching applications. Each of the two independent drivers can source and sink up to 1.5A of peak current, enabling rapid charging and discharging of the MOSFET gate capacitance for efficient high-frequency operation. The ‘Y’ in the part number indicates the SOIC-8 package, while ‘M’ denotes the industrial temperature grade. The MIC4428 is a member of the MIC44xx family of gate drivers, with various configurations including single, dual, and quad drivers with different current ratings. Key features include TTL/CMOS compatible inputs that interface directly with microcontrollers and PWM controllers, Schmitt-trigger inputs for noise immunity in electrically noisy environments, and under-voltage lockout (UVLO) that prevents improper gate drive when the supply voltage is too low. The matched propagation delays between the two channels make the MIC4428 suitable for synchronous rectifier and bridge applications where timing matching is critical. The device operates from a supply voltage of 4.5V to 18V, supporting both standard logic-level drive (5V-10V) and higher voltage drives for enhanced noise margin. With low quiescent current of only 150 µA per channel, the MIC4428 adds minimal power loss to the system. Latch-up protection ensures robust operation against transient voltage spikes commonly found in power electronics applications.

The MIC4428YM contains two identical, independent gate driver channels within a single package. Each driver consists of an input stage, level translation circuitry, and a push-pull output stage. The input stage features Schmitt-trigger buffers with TTL/CMOS compatible thresholds, providing hysteresis that improves noise immunity – particularly important in switching power supply environments where high di/dt and dv/dt transients are common. When the input transitions from low to high, the internal circuitry drives the push-pull output stage high, sourcing current to charge the external MOSFET gate capacitance. This P-channel output transistor provides the source current needed to turn the MOSFET on quickly. When the input transitions from high to low, the N-channel output transistor turns on, sinking current to discharge the gate capacitance and turn the MOSFET off rapidly. The push-pull output structure ensures both fast turn-on and turn-off, minimizing switching losses in the power MOSFET. Under-voltage lockout (UVLO) circuitry monitors the VDD supply voltage. If VDD drops below the UVLO threshold (typically 3.5V), both outputs are forced low to prevent the MOSFET from operating in the linear region, which could cause excessive power dissipation and device failure. The UVLO function has hysteresis to prevent chattering at the threshold. The two drivers are completely independent, with separate input pins and separate output pins, allowing them to be used for completely unrelated functions or in complementary configurations for half-bridge and synchronous rectifier applications.

• Switch-mode power supplies and DC-DC converter designs
• Motor drive circuits including BLDC and stepper motor drivers
• Class-D audio amplifier output stages
• Synchronous rectifier drivers in high-efficiency converters
• LED lighting drivers and solid-state relays
• Pulse transformer and relay coil drivers