ICE3BR0665JZ Infineon Technologies, ICE3BR0665JZ Datasheet - Page 15

• Manufacturer Part Number: ICE3BR0665JZ
• Description: Off-Line SMPS Current Mode Controller
• Manufacturer: Infineon Technologies

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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 Auto Restart Mode, a further
extendable Blanking Time is achieved by adding
external capacitor at BA pin. By means of this Blanking
Time, the IC avoids entering into these two modes
accidentally. Furthermore those buffer time for the
overload detection is very useful for the application that
works in low current but requires a short duration of
high current occasionally.
3.7.1
Figure 22
There are 2 kinds of Blanking mode; basic mode and
the extendable mode. The basic mode is just an
internal set 20ms blanking time while the extendable
mode has an extra blanking time by connecting an
external capacitor to the BA pin in addition to the pre-
set 20ms blanking time. For the extendable mode, the
gate G5 is blocked even though the 20ms blanking time
is reached if an external capacitor C
pin. While the 20ms blanking time is passed, the switch
S1 is opened by G2. Then the 0.9V clamped voltage at
BA pin is charged to 4.0V through the internal I
constant current. G5 is enabled by comparator C3.
Version 2.0
#
C
BK
BA
FB
4.0V
4.0V
1.35V
S1
Control Unit
Basic and Extendable Blanking Mode
Basic and Extendable Blanking Mode
0.9V
C3
C4
C5
I
BK
G2
1
Blanking
Blanking
20ms
Time
20ms
Time
5.0V
G5
&
G6
BK
&
Blanking
Spike
30us
Control Unit
is added to BA
Restart
Mode
Auto
Active
Mode
Burst
BK
15
After the 30us spike blanking time, the Auto Restart
Mode is activated.
For example, if C
Blanking time = 20ms + C
In order to make the startup properly, the maximum C
capacitor is restricted to less than 0.65uF.
The Active Burst Mode has basic blanking mode only
while the Auto Restart Mode has both the basic and the
extendable blanking mode.
3.7.2
The IC enters Active Burst Mode under low load
conditions. With the Active Burst Mode, the efficiency
increases significantly at light load conditions while still
maintaining a low ripple on V
load jumps. During Active Burst Mode, the IC is
controlled by the FB signal. Since the IC is always
active, it can be a very fast response to the quick
change at the FB signal. The Start up Cell is kept OFF
in order to minimize the power loss.
Figure 23
The Active Burst Mode is located in the Control Unit.
Figure 23 shows the related components.
3.7.2.1
The FB signal is kept monitoring by the comparator C5.
During normal operation, the internal blanking time
counter is reset to 0. Once the FB signal falls below
1.35V, it starts to count. When the counter reach 20ms
FB
1.35V
4.0V
3.5V
3.0V
Active Burst Mode
Entering Active Burst Mode
Active Burst Mode
BK
C6a
C6b
C4
C5
= 0.22uF, I
20 ms Blanking
Functional Description
Time
BK
Control Unit
OUT
x (4.0 - 0.9) / I
BK
ICE3BR0665JZ
and a fast response on
= 13uA
G6
&
Internal Bias
12 Nov 2009
G11
&
BK
Active
Mode
Burst
= 72ms
Current
Limiting
G10
&
BK