ICE1HS01G-1 Datasheet, PDF (7/19 Pages) Infineon Technologies AG – Half-Bridge Resonant Controller

Half-Bridge Resonant Controller
ICE1HS01G-1
3 Functional description
The controller ICE1HS01G-1 with two gate outputs is
specially designed for LLC resonant half-bridge
converters. An oscillator with accurately-programmed
frequency range is built inside the IC. The two gate
signals are obtained by passing the signal out from the
oscillator through a divide-by-two flip-flop. Therefore,
two signals are of exactly 50% duty cycle and 180^o out
of phase. To guarantee the zero-voltage-switching and
safe operation in half-bridge topologies, a fixed dead
time of 380ns is inserted in each internal when one
switch is turned off and the other is turned on.
For LLC resonant half-bridge converter, the output
voltage is regulated by changing the switching
frequency. ICE1HS01G-1 offers the designer to
choose suitable operation frequency range by
programming the oscillator with one single resistor.
In addition, ICE1HS01G-1 offers a programmed soft-
start function to limit both the inrush current and the
overshoot in output voltage.
To protect the system during operation, mains input
under-voltage protection and over-current protection
are integrated in ICE1HS01G-1 as well.
3.1 Oscillator and Pulse Frequency
Modulation
The oscillator is programmed with only one external
resistor R_FMIN connected to FMIN pin. The trimmed
capacitor C_FS is built inside the IC with high accuracy.
The simplified oscillator circuit is shown in Figure 3.
1.5V
QF1
FMIN
CF1
RFMIN
ISS
FB
IFB
ICS
CS
Vdd
QF2
QF3
I_{chg_min}
ICE1HS01G
S
Q
I_chg
R
VCH
CO1
Idisc
CO2
VCL
CFS
R
Q
S
Figure 3 Simplified oscillator circuit
The charge current I_chg is sum of four currents which
are I_{chg_min}, I_FB, I_CS and I_SS.
I_chg = I_chgmin + I_FB + I_cs + I_ss
[1]
Functional description
Everytime the capacitor C_FS is charged by I_chg to V_CH,
the upper switch is turned off and C_FS will be
discharged through I_disc. The charge time determines
the on time for gate signal. The discharge time
determines the dead time during transition from one
gate off to another gate on. The switching waveforms
of the oscillator and gate signals are shown in Figure 4.
V_CF
4V
1V
V_delay
t
5V
0V
V_LG
t
10V
0V
V_HG
t
10V
0V
t_d
t
Figure 4 Oscillator waveforms
According to Figures 3 and 4, the on time of each gate
can be obtained as
T_on = ^3--I--C-_c--_h-^F-_g--^S
[2]
The switching frequency can be obtained as
f_s = _{2----èæ}---3----I---C--_c----_h---_F-g--1--_S----+-----T----_d--_øö-
[3]
where the dead time T_d is fixed as 380ns.
3.1.1
Minimum charge current
The voltage on pin FMIN is a constant of 1.5V during
normal operation. The resistor R_FMIN determines the
current (I_FMIN) flowing out from FMIN pin. Around one-
tenth of I_FMIN is defined as the minimum charging
current (I_{chg_min}), which in turn defines the minimum
switching frequency as follows.
Version 2.0
7
02 July 2011