MCP14E9 datasheet(14/30 Pages) MICROCHIP

14 / 30 page

MCP14E9/10/11

DS25005A-page 14

FIGURE 4-3:

Enable Timing Waveform.

4.4

Decoupling Capacitors

Careful layout and decoupling capacitors are highly

recommended when using MOSFET drivers. Large

currents are required to charge and discharge capaci-

tive loads quickly. For example, approximately 2.0A are

needed to charge an 1800 pF load with 18V in 15 ns.

To operate the MOSFET driver over a wide frequency

range, with low supply impedance, a ceramic and low-

ESR film capacitors are recommended to be placed in

parallel, between the driver, VDD and GND. A 1.0 µF,

low-ESR film capacitor and a 0.1 µF ceramic capacitor

placed between pins, 6 and 3, should be used. These

capacitors should be placed close to the driver to mini-

mize circuit board parasitics and provide a local source

for the required current.

4.5

PCB Layout Considerations

A proper PCB layout is important in a high-current, fast

switching circuit, to provide proper device operation

and robustness to the design. The PCB trace loop area

and inductance should be minimized by the use of

ground planes or trace under MOSFET gate drive sig-

nals, separate analog and power grounds, and local

driver decoupling.

Placing a ground plane beneath the MCP14E9/10/11

will help as a radiated noise shield, as well as providing

some heat sinking for power dissipated within the

device.

4.6

Power Dissipation

The total internal power dissipation in a MOSFET driver

is the summation of three separate power dissipation

elements (Equation 4-1).

EQUATION 4-1:

4.6.1

CAPACITIVE LOAD DISSIPATION

The power dissipation caused by a capacitive load is a

direct function of frequency, total capacitive load and

supply voltage. The power lost in the MOSFET driver

for a complete charging and discharging cycle of a

MOSFET is:

EQUATION 4-2:

TABLE 4-1:

ENABLE PIN LOGIC

MCP14E9

MCP14E10

MCP14E11

ENB_A

ENB_B

IN A

IN B

OUT A

OUT B

OUT A

OUT B

OUT A

OUT B

HHHH

HHH

LLLLLL

ENB_x

VDD

OUT x

VEN_H

VEN_L

90%

10%

tD3

tD4

Where:

Total Power Dissipation

Load Power Dissipation

Quiescent Power Dissipation

PCC

Operating Power Dissipation

Where:

f = Switching Frequency

CT = Total Load Capacitance

VDD = MOSFET Driver Supply Voltage

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