ICE2A180 Infineon Technologies Corporation, ICE2A180 Datasheet - Page 11

• Manufacturer Part Number: ICE2A180
• Manufacturer: Infineon Technologies Corporation

3.5.2
In case of overcurrent detection by I
of CoolMOS™ is delayed due to the propagation delay
of the circuit. This delay causes an overshoot of the
peak current I
the peak current (see Figure 14).
.
Figure 14 Current Limiting
The overshoot of Signal2 is bigger than of Signal1 due
to the steeper rising waveform.
A propagation delay compensation is integrated to
bound the tolerance of the dependence on dI/dt of the
internal current limiting at ± 5%. That means the
propagation delay time between exceeding the current
sense threshold V
is compensated over temperature within a range of at
least.
So current limiting is now capable in a very accurate
way (see Figure 16).
Figure 15 Dynamic Voltage Threshold V
Datasheet
Preliminary Data
0
I
I
I
p ea k 2
p ea k 1
L im it
V
V
O S C
c s th
I
V
S e ns e
S en s e
R
Sense
Propagation Delay Compensation
peak
S ig n a l1
I
O v ers h oo t2
dI
S ig n a l2
which depends on the ratio of dI/dt of
csth
dt
peak
and the switch off of CoolMOS™
P ro p a g a tio n D e la y
Preliminary Specification
1
dV
S ig n a l1
S ig n a l2
dt
Sense
Limit
t
P ro pa ga tion D e la y
the shut down
csth
I
O v e rs ho ot1
t
t
11
The propagation delay compensation is done by
means of an dynamic voltage threshold V
Figure 15). In case of a steeper slope the switch off of
the driver is earlier to compensate the delay.
E.g. I
delay compensation the current sense threshold is set
to a static voltage level V
dI/dt = 0.4A/µs, that means dV
propagation delay time of i.e. t
leads then to a I
propagation delay compensation the overshoot is only
about 2% (see Figure 16).
Figure 16
3.6
The oscillator clock output applies a set pulse to the
PWM-Latch when initiating CoolMOS™ conduction.
After setting the PWM-Latch can be reset by the PWM-
OP, the Soft-Start-Comparator, the Current-Limit-
Comparator, Comparator C3 or the Error-Latch of the
Protection Unit. In case of reseting the driver is shut
down immediately.
3.7
The driver-stage drives the gate of the CoolMOS™
and is optimized to minimize EMI and to provide high
circuit efficiency. This is done by reducing the switch on
slope when reaching the CoolMOS™ threshold. This is
achieved by a slope control of the rising edge at the
driver’s output (see Figure 17).
Thus the leading switch on spike is minimized. When
CoolMOS™ is switched off, the falling shape of the
driver is slowed down when reaching 2V to prevent an
overshoot below ground. Furthermore the driver circuit
is designed to eliminate cross conduction of the output
stage. At voltages below the undervoltage lockout
threshold V
1,25
1,15
1,05
0,95
1,3
1,2
1,1
0,9
peak
V
1
0
= 0.5A with R
0,2
PWM-Latch
Driver
VCCoff
Overcurrent Shutdown
0,4
the gate drive is active low.
peak
0,6
with compensation
overshoot of 12%. By means of
Functional Description
0,8
Sense
csth
ICE2A165/265/365
1
dV
=1V. A current ramp of
= 2 . Without propagation
dt
Sense
Sense
1,2
without compensation
Propagation Delay
ICE2A180/280
CoolSET™-II
/dt = 0.8V/µs, and a
1,4
± 5 % T olera nce
February 2001
1,6
1,8
csth
=180ns
2
(see
V
s