MCP1401/02

DS20002052D-page 10

 2007-2014 Microchip Technology Inc.

4.0

APPLICATION INFORMATION

4.1

General Information

MOSFET drivers are high-speed, high-current devices

which are intended to source/sink high peak currents to

charge/discharge the gate capacitance of external

MOSFETs or IGBTs. In high-frequency switching power

supplies, the PWM controller may not have the drive

capability to directly drive the power MOSFET. A

MOSFET driver like the MCP1401/02 family can be

used

to

provide

additional

source/sink

current

capability.

4.2

MOSFET Driver Timing

The ability of a MOSFET driver to transition from a fully-

off state to a fully-on state is characterized by the

can typically charge and discharge a 470 pF load

capacitance in 19 ns, along with a typical matched

the test circuit and timing waveform used to verify the

MCP1401/02 timing.

FIGURE 4-1:

Inverting Driver Timing

Waveform.

FIGURE 4-2:

Non-Inverting Driver Timing

Waveform.

4.3

Decoupling Capacitors

Careful layout and decoupling capacitors are highly

recommended when using MOSFET drivers. Large

currents are required to charge and discharge

capacitive loads quickly. For example, approximately

550 mA are needed to charge a 470 pF load with 18V

in 15 ns.

To operate the MOSFET driver over a wide frequency

range with low supply impedance, it is recommended to

place a ceramic and low ESR film capacitor in parallel

film capacitor and a 0.1 µF ceramic capacitor placed

between pins 2 and 1 should be used. These

capacitors should be placed close to the driver to

minimize circuit board parasitics and provide a local

source for the required current.

4.4

PCB Layout Considerations

Proper Printed Circuit Board (PCB) layout is important

in a high-current, fast switching circuit to provide proper

device operation and robustness of design. PCB trace

loop area and inductance should be minimized by the

use of ground planes or trace under MOSFET gate

drive signals, separate analog and power grounds, and

local driver decoupling.

Placing a ground plane beneath the MCP1401/02 will

help as a radiated noise shield and it will provide some

heat sinking for power dissipated within the device.

0.1 µF

+5V

10%

90%

10%

90%

10%

90%

18V

1µF

0V

0V

MCP1401

Input

Input

Output

Output

Ceramic

90%

Input

Output

10%

10%

10%

+5V

18V

0V

0V

90%

90%

0.1 µF

1µF

MCP1402

Input

Output

Ceramic