Datasheet

 2006-2012 Microchip Technology Inc. DS22019B-page 11
MCP1406/07
4.0 APPLICATION INFORMATION
4.1 General Information
MOSFET drivers are high-speed, high current devices
which are intended to provide high peak currents to
charge 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 MCP1406/07 family can be used to provide
additional drive 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 are characterized by the driv-
ers’ rise time (t
R
), fall time (t
F
), and propagation delays
(t
D1
and t
D2
). The MCP1406/07 family of devices is
able to make this transition very quickly. Figure 4-1 and
Figure 4-2 show the test circuits and timing waveforms
used to verify the MCP1406/07 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 capaci-
tive loads quickly. For example, 2.25A are needed to
charge a 2500 pF load with 18V in 20 ns.
To operate the MOSFET driver over a wide frequency
range with low supply impedance, a ceramic and a low
ESR film capacitor 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 1, 8 and 4, 5 should be used.
These capacitors should be placed close to the driver
to minimized circuit board parasitics and provide a local
source for the required current.
0.1 µF
+5V
10%
90%
10%
90%
10%
90%
18V
1µF
0V
0V
MCP1406
C
L
= 2500 pF
Input
Input
Output
t
D1
t
F
t
D2
Output
t
R
V
DD
= 18V
Ceramic
90%
Input
t
D1
t
F
t
D2
Output
t
R
10%
10%
10%
+5V
18V
0V
0V
90%
90%
0.1 µF
1µF
MCP1407
C
L
= 2500 pF
Input Output
V
DD
= 18V
Ceramic