CoolSET®-F3R
ICE3BR4765J
Functional Description
3
Functional Description
All values which are used in the functional description In order to increase the robustness and safety of the
are typical values. For calculating the worst cases the system, the IC provides Auto Restart protection. The
min/max values which can be found in section 4 Auto Restart Mode reduces the average power
Electrical Characteristics have to be considered.
conversion to a minimum level 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. To make the protection more
flexible, an external auto-restart enable pin is provided.
When the pin is triggered, the switching pulse at gate
will stop and the IC enters the auto-restart mode after
the pre-defined spike blanking time.
3.1
Introduction
CoolSET®-F3R jitter series (ICE3BRxx65J) is the latest
version of the CoolSET®-F3 for the lower power
application. The particular enhanced features are the
built-in features for soft start, blanking window and
frequency jitter. It provides the flexibility to increase the
blanking window by simply addition of a capacitor in BA
pin. In order to further increase the flexibility of the
protection feature, an external auto-restart enable
features are added. Moreover, the proven outstanding
features in CoolSET®-F3 are still remained such as the
active burst mode, propagation delay compensation,
modulated gate driving, auto-restart protection for Vcc
overvoltage, over temperature, over load, open loop,
etc.
The internal precise peak current control reduces the
costs for the transformer and the secondary diode. The
influence of the change in the input voltage on the
maximum 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. Thus there is no need for the over-sizing of the
SMPS, e.g. the transformer and the output diode.
The intelligent Active Burst Mode can effectively obtain
the lowest Standby Power at light load and no load
conditions. After entering the burst mode, there is still a
full control of the power conversion to the output
through the optocoupler, that is used for the normal
PWM control. The response on load jumps is optimized
and the voltage ripple on Vout is minimized. The Vout is
on well controlled in this mode.
Furthermore, this F3R series implements the
frequency jitter mode to the switching clock such that
the EMI noise will be effectively reduced.
3.2
Power Management
Drain
VCC
The usually external connected RC-filter in the
feedback line after the optocoupler is integrated in the
IC to reduce the external part count.
Startup Cell
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.
Depl. CoolMOS™
Power Management
Internal Bias
Undervoltage Lockout
18V
Adopting the BiCMOS technology, it can increase the
design flexibility as the Vcc voltage range is increased
to 25V.
10.5V
The CoolSET®-F3R has a built-in 20ms soft start
function. It can further save external component
counts.
5.0V
Voltage
Reference
Power-Down Reset
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 by
adding an external capacitor at the BA pin in addition to
the basic mode blanking time. During this blanking time
window the overload detection is disabled. With this
concept no further external components are necessary
to adjust the blanking window.
Auto Restart
Mode
Soft Start block
Active Burst
Mode
Figure 3
Power Management
Version 2.5
8
19 Nov 2012
INFINEON [ Infineon ]
