ice3ar4780jz Infineon Technologies Corporation, ice3ar4780jz Datasheet - Page 14

• Manufacturer Part Number: ice3ar4780jz
• Description: Off-line Smps Current Mode Controller With Integrated 800v Coolmos And Startup Cell Brownout & Frequency Jitter In Dip- 7
• Manufacturer: Infineon Technologies Corporation

For example, I
threshold is set to a static voltage level V
Propagation Delay Compensation. A current ramp of dI/dt =
0.4A/µs, or dV
time of t
14.4%. With the propagation delay compensation, the
overshoot is only around 2% (Figure 20).
Figure 20
The Propagation Delay Compensation is realized by means
of a dynamic threshold voltage V
steeper slope the switch off of the driver is earlier to
compensate the delay.
Figure 21
Similarly, the same concept of propagation delay
compensation is also implemented in burst mode with
reduced
implementation, the entry and exit burst mode power can be
very close between low line and high line input voltage.
Version 2.0
V
V
V
OSC
csth
Sense
1,25
1,15
1,05
0,95
1,3
1,2
1,1
0,9
V
1
Propagation Delay
0
max. Duty Cycle
level,
0,2
peak
Signal1
Overcurrent Shutdown
Dynamic Voltage Threshold V
Sense
0,4
= 0.5A with R
V
/dt = 0.8V/µs, and a propagation delay
with compensation
0,6
csth_burst
=180ns leads to an I
0,8
dV
1
off time
Propagation Delay
(Figure
dt
Sense
Sense
csth
1,2
without compensation
(Figure 21). In case of a
= 2. The current sense
1,4
Signal2
17).
1,6
peak
csth
csth
1,8
=1V without
overshoot of
With
2
t
t
µ
V
s
this
14
3.7
The Control Unit contains the functions for Active Burst
Mode and Auto Restart Mode. The Active Burst Mode and
the Auto Restart Mode both have 20ms internal blanking
time. For the over load Auto Restart Mode, the 20ms
blanking time can be further extended by adding an external
capacitor at BBA pin. With the blanking time, the IC avoids
entering into those two modes accidentally. Those buffer
time is very useful for the application which works in short
duration of peak power occasionally.
3.7.1
Figure 22
There are 2 kinds of Blanking mode; basic mode and the
extendable mode. The basic mode is a built-in 20ms
blanking time while the extendable mode can extend this
blanking time by connecting an external capacitor to the
BBA pin. For the extendable mode, the gate G5 remains
blocked even though the 20ms blanking time is reached.
After reaching the 20ms blanking time the counter is
activated and the switch S1 is turned on to charge the voltage
of BBA pin by the constant current source, I
voltage of BBA pin hits 4.5V, which is sensed by comparator
C11, the counter will increase the counter by 1. Then it
switches off the switch S1 and turns on the switch S2. The
voltage at BBA pin will be discharged through a 500Ω
resistor. When the voltage drops to 0.9V which is sensed by
comparator C3, the switch S2 will be turned off and the
switch S1 will be turned on. Then the constant current I
will charge the C
BBA hits 4.5V which is sensed by comparator C11, the
counter will increase the count to 2. The process repeats until
it reaches total count of 256 (Figure 23). Then the counter
will release a high output signal. When the AND gate G5
R
BO2
#
C
BK
Control Unit
Basic and Extendable Blanking Mode
BBA
FBB
4.5V
Basic and Extendable Blanking Mode
S1
S2
5.0V
BK
500Ω
capacitor again. When the voltage at
I
4.5V
0.9V
chg_EB
C4
Functional Description
C11
C3
CoolSET
Blanking
ICE3AR4780JZ
20ms
Time
Counter
CT1
chg_EB
26 Aug 2010
Control Unit
®
-F3R80
. When the
Blanking
Restart
Spike
Mode
30us
Auto
G5
&
chg_EB