AN-8102 Datasheet, PDF (1/5 Pages) Fairchild Semiconductor – Recommendations to Avoid Short Pulse Width Issues

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AN-8102
Recommendations to Avoid Short Pulse Width Issues in
HVIC Gate Driver Applications
1. Introduction
The High-Voltage Integrated Circuit (HVIC) gate driver
family is designed to drive an N-channel MOSFET or IGBT
up to 600 V. One of the most common methods to supply
power to the high-side gate drive circuitry of the high-voltage
gate drive IC is the bootstrap power supply. This bootstrap
power supply technique has the advantage of being simple
and low cost. However, duty cycle is limited by the
requirement to charge the bootstrap capacitor and serious
problems occur when extremely short pulse width is used in
the application system. This application note explains the
features of HVIC gate drivers and provides recommendations
to avoid short pulse-width issues in the application.
In the HVIC gate driver block diagram shown in Figure 1, a
typical HVIC gate driver consists of input, pulse generator,
level shifter, Under-Voltage Lockout (UVLO), control latch,
and driver circuit. HVIC gate driver IC uses bootstrap
method to control MOSFET and IGBT. By adding a
bootstrap circuit outside the HVIC, the high side can be
supplied with a signal power source. This kind of “floating
supply” is suitable for providing gate drive circuitry to
directly drive high-side switches that operate up to rail
voltages. The basic application circuit of the bootstrap
supply, shown in Figure 2, is comprised of bootstrap diode
(D1) and capacitor (C1).
HIN
Set
HIN 1
200K
Reset
Reset
Set
UVLO
NOISE
CANCELLER
RST
R _Control
S ^Latch Q
LIN 2
200K
UVLO
DELAY
VSS/COM
LEVEL
SHIFT
8 VB
7 HO
6 VS
5 VDD
4 LO
3 COM
FAN7190 Rev1.0
Figure 1. Block Diagram of High-Voltage Gate Driver IC
MCU
V_CC
D1
VCC
5
VB
8
LIN
2
HO
7
HIN
1
VS
6
GND
LO
3
4
FAN7190
600V
Floating Power
Supply
Rg2
C1
Rg1
Load
Figure 2. Typical Application Circuit for FAN7190
© 2012 Fairchild Semiconductor Corporation
Rev. 1.3 • 4/28/15
www.fairchildsemi.com