ICE1HS01G-1 Datasheet, PDF (9/19 Pages) Infineon Technologies AG – Half-Bridge Resonant Controller

Half-Bridge Resonant Controller
ICE1HS01G-1
Figure 8 shows the maximum switching frequency
versus minimum switching frequency during softstart.
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0
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100 125 150 175 200
FMIN [kHz]
Figure 8 Fmax_ss versus Fmin during soft start
Functional description
3.4 Current sense
Current sense in LLC half bridge converters is for
protection purpose. The voltage of resonant capacitor
C_S is the sum of the resonant voltage and the dc
voltage which is equal to half of the input bus voltage.
If resonant current is higher, then the voltage on C_S is
higher.The current informations for both primary side
and secondary side are almost the same and can be
obtained by dividing and filtering the resonant voltage.
The circuit is shown in Figure 10.
V_BUS ^Q1
Q₂
W_P
C_S
3.2 IC power supply
The controller ICE1HS01G-1 is targeting at
applications with auxiliary power supply. In most cases,
a front-end PFC pre-regulator with a PFC controller is
used in the same system.
The controller ICE1HS01G-1 starts to operate when
the supply voltage V_VCC reaches the on-threshold,
V_VCCon of 12V. The minimum operating voltage after
turn-on, V_VCCoff, is at 11V. The maximum
recommended operating voltage V_VCCmax is 18V.
3.3 Soft start
At the beginning of the startup phase, the IC provides
a soft start with duration of 32ms with 32 steps. During
this period, the switching frequency is controlled
internally by changing the current I_SS.
Figure 9 illustrates the actual switching frequency vs.
startup time when R_FMIN=22kohm. During softstart, the
frequency starts from 250kHz, and step by step drops
to normal operation point.
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150
100
V_CS
C_CS2
D_CS1
R_CS2
R_CS1
C_CS1
D_CS2
Figure 10 Current sense circuit
3.5 Over current protection
The controller ICE1HS01G-1 incorporates two-level
over current protection. In case of over-load condition,
the lower level OCP will be triggered, the switching
frequency will be increased according to the duration
and power of the over load. The higher level OCP is
used to protect the converter if transformer winding is
shorted, the IC will be latched immediately.
If V_CS is higher than 0.8V, IC will boost up the switching
frequency. If Vcs is lower than 0.75V, IC will resume to
normal operation gradually. If V_CS is always higher than
0.8V for 1.5ms, the frequency will rise to its maximum
level. And vice versa.
To sum up, ICE1HS01G-1 will increase the switching
frequency to limit the resonant current in case of
temporary over-load and will also decrease the
switching frequency to its normal value after over-load
condition goes away.
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0
0
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25
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35
Time [ms]
Figure 9
Switching frequency during softstart
when R_FMIN=22kohm
During soft start, the overload protection is disabled
although FB voltage is high.
3.6 Mains Input Voltage Sense
The working range of mains input voltage needs to be
specified for LLC resonant converter. It is important for
the controller to have input voltage sensing function
and protection features, which lets the IC stop
switching when the input voltage falls below the
specified range and restarts when the input voltage
increases back within the range. The mains input
voltage sensing circuit is shown Figure 2. With the
Version 2.0
9
02 July 2011