ICE3B0365J Datasheet, PDF (7/26 Pages) Infineon Technologies AG – Off-Line SMPS Current Mode Controller with integrated 650V Startup Cell/Depletion CoolMOS™

CoolSET™-F3
ICE3Bxx65J
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.
3.2
Drain
Power Management
VCC
3.1
Introduction
CoolSET™-F3 Jitter version 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 18V 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.
An Auto Restart Mode is implemented in the IC to
reduce the average power conversion in the event of
malfunction or unsafe operating condition in the SMPS
system. This feature increases the system’s
robustness and safety which would otherwise lead to a
destruction of the SMPS. 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
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.
Startup Cell
Power Management
Internal Bias
Power-Down Reset
T1
Undervoltage Lockout
18V
10.3
5V
Voltage
Reference
Auto Restart
Mode
Active Burst
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. The VCC charge current
that is provided by the Startup Cell from the Drain pin is
1.05mA. When V_VCC exceeds the on-threshold
V_CCon=18V, bias circuit is 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 10.3V.
The maximum current consumption before the
controller is activated is about 300uA.
Version 2.3
7
8 May 2006