ICE3A1065ELJ Datasheet, PDF (8/29 Pages) Infineon Technologies AG – Off-Line SMPS Current Mode Controller with integrated 650V CoolMOS

CoolSET^®-F3
ICE3A1065ELJ
Functional Description
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.
3.1
Introduction
CoolSET^®-F3 ELJ series is the enhanced version of the
LJ series. Not only retains all the features of LJ series
but it also implements with special technique to make
the IC more robust to the system noise which is
generated during transient test, system ESD test,
lightning surge test, etc.
In order to obtain the best-in class low standby power,
a new fully integrated Standby Power concept is
implemented into the IC. 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 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 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.
This version is adopting the BiCMOS technology and it
can increase design flexibility as the Vcc voltage range
is increased to 26V.
For this ELJ version, the soft start is a built-in function.
It is set at 20ms. Then it can save external component
counts.
There are 2 modes of blanking time for high load
jumps; the basic mode and the extendable mode. The
blanking time for the basic mode is set at 20ms while
the extendable mode will increase the blanking time
from basic mode by adding external capacitor at the BL
pin. During this time window the overload detection is
disabled.
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 recycling the AC line. In addition, for this ELJ
version, there is an external Latch Enable function
provided to increase the flexibility in protection. When
the BL pin is pulled down to less than 0.1V, the Latch
Off Mode is triggered.
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 retained 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.
Furthermore, this ELJ version implements the
frequency jitter mode to the switching clock such that
the EMI noise will be effectively reduced.
3.2
Power Management
Drain
VCC
Startup Cell
C oolM O S ^®
Power Management
Internal Bias
Latched Off Mode
Reset
VVCC < 6.23V
Power-Down Reset
Soft Start block
Undervoltage Lockout
18V
10.5V
Voltage
Reference
5.0V
Auto Restart
Mode
Active Burst
Mode
Latched Off
Mode
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
Version 2.1
8
12 May 2009