I
NTEGRATED
C
IRCUITS
D
IVISION
IX2120
R02 www.ixysic.com 7
1.9 IX2120 Typical Application
The IX2120 is a 1200V half bridge gate driver for high
voltage IGBTs and MOSFETs. Three input signals
(HIN, LIN, and SD) determine the state of the gate
driver outputs (HO and LO). HIN controls HO via a
high voltage interface. The high voltage interface is
integrated into the bootstrap supply by using two 600V
diodes (DD1 and DD2).
A two-stage bootstrap supplies current to the high side
and mid level circuitry. The two bootstrap circuits are
identical, and careful board layout and positioning of
the bootstrap components are required. Resistors
RD1 and RD2 form a resistive divider to keep the mid
supply very near the center of the high voltage supply
range. High value resisters (5M) are recommended
to minimize power dissipation. The two-stage
bootstrap supply reduces the high side gate drive
voltage (V
B
-V
S
) by two diode forward voltage drops
(2V
F
). Therefore, the V
CC
supply range for the
application circuit shown is:
Where V
CE(sat)
M2 is the saturation voltage of IGBT,
M2.
The high side bootstrap capacitor selection is a
function of the switching frequency and the on-time
(t
ONTIME
) of the high side source driver. The quiescent
V
BS
current (I
QBS
) is supplied by bootstrap capacitor
CB2, and the quiescent V
BMSM
supply current
(I
QBMSM
) is supplied by bootstrap capacitor CB1. To
insure adequate supply current:
and:
V
DD
V
SS
VHV
COM
M1
1200V
M2
1200V
DR2
1200V
DR1
1200V
RB1
5
RB2
5
R12
4.7
R22
4.7
R11
47
R21
47
V
S
1
V
B
2
N/C
3
HO
4
N/C
5
N/C
6
N/C
7
N/C
8
N/C
9
V
DD
10
HIN
11
SD
12
LIN
13
V
SS
14
LO
15
N/C
16
COM
17
N/C
18
V
CC
19
N/C
20
N/C
21
V
SM
22
V
BM
23
V
SM
24
N/C
25
N/C
26
N/C
27
N/C
28
IX2120
DG2
25V
DG1
25V
DB1
DB2
DD2
600V
DD1
600V
600V
600V
C1
1µF
V
CC
HIN
SD
LIN
25V
CB1
0.33µF
25V
CB2
0.33µF
25V
C3
1µF
25V
RD2
5M
RD1
5M
20VV
CC
V
BSUV+
2V
F
V
CE sat
M2++
CB1 I
QBS
t
ONTIME
V
CC
V
BSUV+
2VF V
CE sat
M2++–
---------------------------------------------------------------------------------------------
CB2 I
QBMSM
t
ONTIME
V
CC
V
BSUV+
2VF V
CE sat
M2++–
---------------------------------------------------------------------------------------------
