ice2qr1065z Infineon Technologies Corporation, ice2qr1065z Datasheet - Page 10

• Manufacturer Part Number: ice2qr1065z
• Description: Of F -line Smps Quasi -resonant Pwm Cont Rol Ler Wi Th Integrated 650v Coolmos And Startup Cell In Dip-7
• Manufacturer: Infineon Technologies Corporation

required maximum V
voltage can be calculated, which is shown in
Figure 6
According to the typical application circuit, when
MOSFET is turned on, a negative voltage proportional
to bus voltage will be coupled to auxiliary winding.
Inside CoolSET
voltage on ZC pin to nearly 0V. As a result, the current
flowing out from ZC pin can be calculated as
When this current is higher than I
current exceeding this threshold is used to generate an
offset to decrease the maximum limit on V
ideal curve shown in
digital block in CoolSET
better control of maximum output power. Additional
advantage to use digital circuit is the production
tolerance is smaller compared to analog solutions. The
typical maximum limit on V
shown in
Figure 7
3.5
At light load condition, the IC enters Active Burst Mode
operation to minimize the power consumption. Details
Version 2.0
I
ZC
0.9
0.8
0.7
0.6
1
0.9
0.8
0.7
0.6
80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400
1
=
300
V
------------------------
R
Figure
BUS
ZC1
Variation of the VCS limit voltage according
to the I
500
Active Burst Mode Operation
V
N
N
CS-max
®
700
P
a
7.
- Q1, an internal circuit will clamp the
ZC
current
900
versus I
Figure 6
CS
®
1100
- Q1 is implemented to get a
versus various input bus
Vin(V)
Izc(uA)
CS
ZC
versus the ZC current is
1300
is a nonlinear one, a
ZC_1
1500
, the amount of
1700
CS
. Since the
1900
Figure
2100
[5]
6.
10
about Active Burst Mode operation are explained in the
following paragraphs.
3.5.1
For determination of entering Active Burst Mode
operation, three conditions apply:
•
•
•
Once all of these conditions are fulfilled, the Active
Burst Mode flip-flop is set and the controller enters
Active Burst Mode operation. This multi-condition
determination for entering Active Burst Mode operation
prevents mistriggering of entering Active Burst Mode
operation, so that the controller enters Active Burst
Mode operation only when the output power is really
low during the preset blanking time.
3.5.2
After entering the Active Burst Mode the feedback
voltage rises as V
inactive PWM section. One comparator observes the
feedback signal if the voltage level V
exceeded. In that case the internal circuit is again
activated by the internal bias to start with switching.
Turn-on of the power MOSFET is triggered by the
timer. The PWM generator for Active Burst Mode
operation composes of a timer with a fixed frequency of
52kHz, typically, and an analog comparator. Turn-off is
resulted by comparison of the voltage signal v
internal threshold, by which the voltage across the
shunt resistor V
also be triggered by the maximal duty ratio controller
which sets the maximal duty ratio to 50%. In operation,
the output flip-flop will be reset by one of these signals
which comes first.
If the output load is still low, the feedback signal
decreases as the PWM section is operating. When
feedback signal reaches the low threshold V
the internal bias is reset again and the PWM section is
disabled until the next regulation signal increases
beyond the V
feedback signal is changing like a saw tooth between
3.0V and 3.6V shown in
3.5.3
The feedback voltage immediately increases if there is
a high load jump. This is observed by one comparator.
As the current limit is 34% during Active Burst Mode a
certain load is needed so that feedback voltage can
exceed V
maximum current can now be provided to stabilize V
In addition, the up/down counter will be set to 1
the feedback voltage is lower than the threshold of
V
voltage across the shunt resistor is 0.17V;
the up/down counter is 7; and
a certain blanking time (t
FBEB
(1.25V). Accordingly, the peak current sense
LB
Entering Active Burst Mode Operation
During Active Burst Mode Operation
Leaving Active Burst Mode Operation
(4.5V). After leaving active burst mode,
BH
csB
threshold. In Active Burst Mode, the
is 0.34V, accordingly. A turn-off can
OUT
Functional Description
starts to decrease due to the
Figure
BEB
).
CoolSET
8.
ICE2QR1065Z
April 25, 2011
BH
(3.6V) is
®
1
BL
with an
(3.0V),
- Q1
O
.