IRPLHALO1E International Rectifier, IRPLHALO1E Datasheet - Page 13

• Manufacturer Part Number: IRPLHALO1E
• Description: KIT HALOGIN CONVERTER 100VA
• Manufacturer: International Rectifier

Specifications of IRPLHALO1E

• Main Purpose: Lighting, Ballast Control
• Utilized Ic / Part: IR2161
• Lead Free Status / RoHS Status: Lead free / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Other names: *IRPLHALO1E

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Note
Ready wound toroidal output transformers as used in the IRPLHALO1E design kit are available
from Vogt or Kaschke. These have many advantages including high isolation breakdown capability
because of the moulded plastic separator between the primary and secondary.
Short circuit current
The short circuit current that appears at the primary is dependent on the primary leakage induc-
tance of the output transformer as well as the value of the half bridge capacitors. The half bridge
capacitors should be kept as small as possible in order to limit this current. However, they also need
to be large enough to be able to handle the ripple current, i.e. half the primary current flowing in
each capacitor at the IR2161 oscillator frequency.
Adaptive Dead Time
Because of the fact that the DC bus voltage varies during the mains half cycle the dead time may
need to vary in order to achieve soft switching all of the time. The IR2161 has an adaptive dead time
system that detects the point at which the voltage at the half bridge slews to 0V (COM) and sets the
LO output high at this point. There is an internal sample and hold system that allows the same delay
to be used to set HO high after LO has gone low. This reacts on a cycle-by-cycle basis of the
oscillator and therefore will adjust the dead time as necessary regardless of external conditions.
The designer does not need to take into account parasitic capacitances in the MOSFETs or leakage
inductance in the output transformer and set the dead time accordingly.
The system is designed operate down to dead times of less than 250nS which should be low
enough to accommodate the output transformer leakage inductance and parasitic MOSFET ca-
pacitances of a practical Halogen convertor. If the ADT function does not operate the dead time
reverts to a preset fixed value that will, in most cases, prevent serious losses due to hard switching.
The slew rate can easily be increased, if necessary, by increasing the value of the snubber capaci-
tor. This does, however result in the failure of the VS voltage to slew completely at reduced loads
and so CSNUB should be kept as low as possible, but high enough to maintain the supply for the
charge pump to VCC. Some of the supply current may also be provided through RD and CD allow-
ing the charge pump to provide only part of it and hence the value of CSNUB can be as low as
220pF.
The IRPLHALO1E reference design board uses a toroidal output transformer that has the
secondary windings spread over as much of the core as possible to minimize the leakage
inductance, which is inherently high in such constructions. This allows sufficient current to
shut down the convertor rapidly when the output is short circuited.
IRPLHALO1E
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