HS01G datasheet(9/18 Pages) INFINEON

9 / 18 page

Version 2.0

24 August 2009

Half-Bridge Resonant Controller

ICE1HS01G

Functional description

Figure 8 shows the maximum switching frequency

versus minimum switching frequency during softstart.

Figure 8

Fmax_ss versus Fmin during soft start

3.2

IC power supply

The controller ICE1HS01G is targetting 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 starts to operate when the

supply voltage VVCC reaches the on-threshold, VVCCon

of 12V. The minimum operating voltage after turn-on,

VVCCoff, is at 11V. The maximum recommended

operating voltage VVCCmax 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 ISS.

Figure 9 illustrates the actual switching frequency vs

startup time when RFMIN=22kohm. During softstart, the

frequency starts from 250kHz, and step by step drops

to normal operation point.

Figure 9

Switching frequency during softstart

when RFMIN=22kohm

During soft start, the overload protection is disabled

although FB voltage is high.

3.4

Current sense

Current sense in LLC half bridge converters is for

protection purpose. The voltage of resonant capacitor

CS 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 CS 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.

Figure 10

Current sense circuit

3.5

Over current protection

The controller ICE1HS01G incorporates two-level over

current protection. In case of over-load condition, the

lower level OCP will be triggerred, 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 VCS 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 VCS is always higher than

0.8V for 1.5ms, the frequency will rise to its maximum

level. And vice versa.

To sum up, ICE1HS01G 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.

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

100

150

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250

300

350

400

450

500

550

100

125

150

175

200

FMIN[kHz]

100

150

200

250

300

Time [ms]

RCS2

RCS1

DCS1

DCS2

CCS1

VCS

VBUS

CCS2

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