ICE1HS01G-1 Datasheet, PDF (8/19 Pages) Infineon Technologies AG – Half-Bridge Resonant Controller

Half-Bridge Resonant Controller
ICE1HS01G-1
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R_FMIN [kohm]
Figure 5
FMIN versus R_FMIN
Functional description
3.1.3
Current sense current I_CS
In LLC resonant topologies, it is necessary to limit the
resonant current in case of short circuit or other fault
conditions. It is achieved by adding another current Ics
to the charging current I_chg. I_CS is limited to 3 times of
the minimum charge current.
3.1.4
Soft start current I_SS
To limit the inrush current and output overshoot during
start up, the switching frequency shall be necessary
high at start up. The switching frequency will change
gradually toward the minimum switching frequency
until the feedback voltage comes into regulation. The
switching frequency will then go to desired value
according to load and input conditions. The soft start
current I_ss also has a upper limit of around 3.4 times of
minimum charge current. Details of soft start will be
shown later.
3.1.2
Feedback regulation
The output information is fed into the controller through
feedback voltage. If the output power is higher, the
feedback voltage will be higher, which will cause the
switching frequency to decrease and vice versa.
The regulation of switching frequency is achieved by
changing the charging current. An accurate operational
transconductance amplifier (OTA) is used to translate
the feedback voltage V_FB into current I_FB. The effective
range of feedback voltage is from 0.9V to 3.9V.
Figure 6 graphs the relationship between the actual
switching frequency and feedback voltage V_FB when
R_FMIN=22kohm.
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Feedback voltage Vfb [V]
3.1.5
Charge current I_chg
The charge current I_chg for IC oscillator capacitor C_FS is
the sum of the four parts including I_{chg_min}, I_FB, I_SS and
I_CS. To limit the maximum switching frequency,
maximum value of I_chg is 5 times of I_{chg_min}.
In summary, the maximum charge current during
normal operation is 3I_{chg_min} while the maximum charge
current during fault condition or softstart is around
4I_{chg_min} and 4.43*I_{chg_min} respectively. Figure 7 shows
the maximum switching frequency versus minimum
switching frequency during normal operation.
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FMIN [kHz]
Figure 7
Fmax versus Fmin during normal
operation
Figure 6 Switching frequency versus V_FB
Burst mode operation is also provided by ICE1HS01G-
1. During LLC operation, the feedback signal V_FB is
continuously monitored. When V_FB drops below V_{FB_off},
the switching signal will be disabled after a fixed
blanking time T_FB. V_FB will then rise as V_out starts to
decrease due to no switching signal. Once V_FB exceeds
the threshold V_{FB_on}, the IC resumes to normal
operation.
Version 2.0
8
02 July 2011