ICE3B0365L Datasheet, PDF (7/28 Pages) Infineon Technologies AG – Off-Line SMPS Current Mode Controller with integrated 650V Startup Cell/Depletion CoolMOS™ and Latched off Mode

CoolSET™-F3
ICE3xxx65L
3 Functional Description
All values which are used in the functional description
are typical values. For calculating the worst cases the
min/max values which can be found in section 4
Electrical Characteristics have to be considered.
Functional Description
power limitation can be avoided together with the
integrated Propagation Delay Compensation.
Therefore the maximum power is nearly independent
on the input voltage which is required for wide range
SMPS. There is no need for an extra over-sizing of the
SMPS, e.g. the transformer or the secondary diode.
3.1
Introduction
CoolSET™-F3 is the further development of the
CoolSET™-F2 to meet the requirements for the lowest
Standby Power at minimum load and no load
conditions. A new fully integrated Standby Power
concept is implemented into the IC in order to keep the
application design easy. Compared to CoolSET™-F2
no further external parts are needed to achieve the
lowest Standby Power. An intelligent Active Burst
Mode is used for this Standby Mode. After entering this
mode there is still a full control of the power conversion
by the secondary side via the same optocoupler that is
used for the normal PWM control. The response on
load jumps is optimized. The voltage ripple on V_out is
minimized. V_out is further on well controlled in this
mode.
The usually external connected RC-filter in the
feedback line after the optocoupler is integrated in the
IC to reduce the external part count.
Furthermore a high voltage Startup Cell is integrated
into the IC which is switched off once the Undervoltage
Lockout on-threshold of 15V is exceeded. This Startup
Cell is part of the integrated Depl. CoolMOS™. The
external startup resistor is no longer necessary as this
Startup Cell is connected to the Drain. Power losses
are therefore reduced. This increases the efficiency
under light load conditions drastically.
The Soft-Start capacitor is also used for providing an
adjustable blanking window for high load jumps.
During this time window the overload detection is
disabled. With this concept no further external
components are necessary to adjust the blanking
window.
In order to increase the robustness and safety of the
system, the IC provides 2 levels of protection modes:
Latched Off Mode and Auto Restart Mode. The
Latched Off Mode is only entered under dangerous
conditions which can damage the SMPS if not
switched off immediately. A restart of the system can
only be done by disconnecting the AC line.
The Auto Restart Mode reduces the average power
conversion to a minimum under unsafe operating
conditions. This is necessary for a prolonged fault
condition which could otherwise lead to a destruction
of the SMPS over time. Once the malfunction is
removed, normal operation is automatically initiated
after the next Start Up Phase.
The internal precise peak current limitation reduces the
costs for the transformer and the secondary diode. The
influence of the change in the input voltage on the
3.2
Power Management
Drain
VCC
Startup Cell
Depl. CoolMOS™
Power Management
Internal Bias
Latched Off Mode
Reset
V_VCC < 6V
Power-Down Reset
Undervoltage Lockout
15V
8.5V
Voltage
6.5V
Reference
Auto Restart
Mode
Active Burst
T1
Mode
Latched Off
Mode
SoftS
Figure 3 Power Management
The Undervoltage Lockout monitors the external
supply voltage V_VCC. When the SMPS is plugged to the
main line the internal Startup Cell is biased and starts
to charge the external capacitor C_VCC which is
connected to the VCC pin. This VCC charge current
which is provided by the Startup Cell from the Drain pin
is 1.05mA. When V_VCC exceeds the on-threshold
V_CCon=15V the internal voltage reference and bias
circuit are switched on. Then the Startup Cell is
switched off by the Undervoltage Lockout and
therefore no power losses present due to the
connection of the Startup Cell to the Drain voltage. To
avoid uncontrolled ringing at switch-on a hysteresis is
implemented. The switch-off of the controller can only
take place after Active Mode was entered and V_VCC
falls below 8.5V.
Version 2.0
7
8 May 2006