EPR-89 Datasheet, PDF (4/32 Pages) Power Integrations, Inc. – Engineering Prototype Report for 2.0 W CV Adapter using LNK362P

EP-89 6.2 V, 322 mA Adapter
08-Nov-2005
On the other hand, an auto-recovering thermal shutdown function eliminates the
occurrence of unnecessary returns from the field, since the end customer may never
even know that a fault condition existed, because the power supply resumes normal
operation once the cause of the fault (a failed battery or blanket inadvertently thrown over
top of a working power adapter or battery charger) is removed. Additionally, the thermal
shutdown function employed in the LinkSwitch-XT does not have the noise sensitivity
associated with discrete latch circuits, which often vary widely with PCB component
layout, environmental conditions (such as proximity to external electronic noise sources)
and component aging.
The IC package has a wide creepage distance between the high-voltage DRAIN pin and
the lower voltage pins (both where the pins exit the package and at the PCB pads). This
is important for reliable operation in high humidity and/or high pollution environments.
The wide creepage distance reduces the likelihood of arcing, which improves robustness
and long-term field reliability.
Another important protection function is auto-restart, which begins operating whenever
there is no feedback from the power supply output for more than 40 ms (such as a short
circuit on the output or a component that has failed open-circuit in the feedback loop).
Auto-restart limits the average output current to about 5 % of the full load rating
indefinitely, and resumes normal operation once the fault is removed.
The worst-case, no-load power consumption of this design is about 110 mW at 265 VAC,
which is well below the 300 mW European Union standards. It also meets the common
target of 150 mW at 230 VAC, that is seen in many particular customer specifications.
The amount of heat dissipated within the supply is minimized by the high operating
efficiency over all combinations of load and line.
The EE16 transformer bobbin that was used also has a wide creepage spacing, which
makes it easy to meet primary-to-secondary safety spacing requirements.
This report contains the complete specification of the power supply, a detailed circuit
diagram, the entire bill of materials required to build the supply, extensive documentation
of the power transformer, along with test data and oscillographs of the most important
electrical waveforms. All of this is intended to document the performance characteristics
that should be typical of a power supply designed around the LNK362 device.
Power Integrations
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www.powerint.com
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