< Dual-In-Line Package Intelligent Power Module >
Series Application note
Publication Date: September 2016
14
2.2 Protection functions and operating sequence
has two protection functions of short circuit (SC) and under voltage of control supply (UV). And it has
also temperature output function of LVIC (VOT). The operating principle and sequence are described as follows.
2.2.1 Short circuit protection
(1) Outline
uses external shunt resistor for the current detection as shown in Fig.2-2-1. The internal protection
circuit inside the IC captures the excessive large current by comparing the CIN voltage generated at the shunt
resistor with the referenced SC trip voltage, and perform protection automatically. The threshold voltage trip level
of the SC protection Vsc(ref) is 0.48V typical.
In case of SC protection works, all the gates of N-side three phase IGBTs will be interrupted together with a
fault signal output. To prevent erroneous protection due to normal switching noise and/or recovery
current, it is necessary to set an RC filter (time constant: 1.5
μ ~ 2μs) to the CIN terminal input (Fig.2-2-1, 2-2-2).
Also, please make the pattern wiring around the shunt resistor as short as possible.
Fig.2-2-1 SC protection circuit Fig.2-2-2 Filtering time constant setting
(2) SC protection sequence for only low-side with external shunt resistor and RC filter
a1. Normal operation: IGBT ON and outputs current.
a2. Short circuit current detection (SC trigger)
(It is recommended to set RC time constant 1.5~2.0
μs so that IGBT shut down within 2.0μs when SC.)
a3. All N-side IGBT's gates are hard interrupted.
a4. All N-side IGBTs turn OFF.
a5. LVIC starts outputting fault signal (fault signal output time is controlled by external capacitor C
FO
)
a6. Input = “L”: IGBT OFF
a7. Fo finishes output, but IGBTs don't turn on until inputting next ON signal (L
H).
(IGBT of each phase can return to normal state by inputting ON signal to each phase.)
a8. Normal operation: IGBT ON and outputs current.
Fig.2-2-3 SC protection timing chart
V
NC
N1
N
C
Shunt resistor
P
V
U
W
N-side IGBTs
P-side IGBTs
Drive circuit
Drive circuit
SC protection circuit
CIN
DIPIPM
R
External parts
Lower-side control
input
Protection circuit state
Internal IGBT gate
Output current Ic
Sense voltage of
the shunt resistor
Error output Fo
SC trip current level
a2
SET
RESET
SC reference voltage
a1
a3
a6
a7
a4
a8
a5
Delay by RC filtering
SC protection level
C
ol
lec
tor
c
ur
rent
Ic
Input pulse width tw (
μs)
2
0
Collector
Current
waveform