Datasheet
MCP14E9/10/11
DS25005A-page 14 © 2011 Microchip Technology Inc.
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, V
DD
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
HHHHL LHHLH
HHHL LHHL L L
HHLHHL LHHH
HHL LHHL LHL
LLXXLLLLLL
5V
0V
ENB_x
V
DD
0V
OUT x
V
EN_H
V
EN_L
90%
10%
t
D3
t
D4
P
T
P
L
P
Q
P
CC
++=
Where:
P
T
= Total Power Dissipation
P
L
= Load Power Dissipation
P
Q
= Quiescent Power Dissipation
P
CC
= Operating Power Dissipation
P
L
fC
T
×
V
DD
2
×
=
Where:
f = Switching Frequency
C
T
= Total Load Capacitance
V
DD
= MOSFET Driver Supply Voltage