IR22141 International Rectifier, IR22141 Datasheet - Page 23

• Manufacturer Part Number: IR22141
• Description: HALF-BRIDGE GATE DRIVER IC
• Manufacturer: International Rectifier

b. Bootstrap Resistor
A resistor (R
strap diode (see figure 19) so to limit the current
when the bootstrap capacitor is initially charged.
We suggest not exceeding some Ohms (typi-
cally 5, maximum 10 Ohm) to avoid increasing
the V
charging the bootstrap capacitor or for refresh-
ing its charge must be verified against this time-
constant.
c. Bootstrap Capacitor
For high T
lytic tank capacitor, its ESR must be consid-
ered. This parasitic resistance forms a voltage
divider with R
at the first charge of bootstrap capacitor. The
voltage step and the related speed (dV
should be limited. As a general rule, ESR should
meet the following constraint:
Parallel combination of small ceramic and large
electrolytic capacitors is normally the best com-
promise, the first acting as fast charge thank for
the gate charge only and limiting the dV
reducing the equivalent resistance while the sec-
ond keeps the V
sired V
d. Bootstrap Diode
The diode must have a BV> 1200V and a fast
recovery time (trr < 100 ns) to minimize the
amount of charge fed back from the bootstrap
capacitor to V
www.irf.com
BS
time-constant. The minimum on time for
BS
HON
.
ESR
boot
boot
designs where is used an electro-
CC
ESR
) is placed in series with boot-
generating a voltage step on V
supply
BS
R
voltage drop inside the de-
BOOT
V
CC
ADVANCE DATA
3
V
BS
/dt by
BS
/dt)
BS
V
Gate resistances
The switching speed of the output transistor can
be controlled by properly size the resistors con-
trolling the turn-on and turn-off gate current. The
following section provides some basic rules for
sizing the resistors to obtain the desired switch-
ing time and speed by introducing the equivalent
output resistance of the gate driver (R
R
The examples always use IGBT power transis-
tor. Figure 20 shows the nomenclature used in
the following paragraphs. In addition, V
cates the plateau voltage, Q
the gate to collector and gate to emitter charge
respectively.
ge
*
DRn
10%
).
t
Don
V
t
CE
1
IR2214/IR22141(SS)
,Q
10%
Figure 20: Nomenclature
GE
90%
t
R
C
dV/dt
RES
t
SW
C
V
t
2
GE
RES
,Q
V
GC
GE
I
C
I
C
gc
and Q
ge
indicate
DRp
ge
*
t,Q
C
C
indi-
and
RESon
RESoff
23