TNY274-280
startup. Repeatundersteadystateconditionsandverifythat
the leading edge current spike event is below ILIMIT(Min)at the
endofthetLEB(Min). Underallconditions, themaximumdrain
current should be below the specified absolute maximum
ratings.
Quick Design Checklist
As with any power supply design, all TinySwitch-III designs
should be verified on the bench to make sure that component
specificationsarenotexceededunderworstcaseconditions. The
following minimum set of tests is strongly recommended:
3. Thermal Check – At specified maximum output power,
minimuminputvoltageandmaximumambienttemperature,
verify that the temperature specifications are not exceeded
for TinySwitch-III, transformer, output diode, and output
capacitors. Enough thermal margin should be allowed for
part-to-part variation of the RDS(ON) of TinySwitch-III as
specifiedinthedatasheet. Underlowline,maximumpower,
a maximum TinySwitch-III SOURCE pin temperature of
110 °C is recommended to allow for these variations.
1. Maximum drain voltage – Verify that VDS does not exceed
650 V at highest input voltage and peak (overload) output
power. The 50 V margin to the 700 V BVDSS specification
gives margin for design variation.
2. Maximumdraincurrent–Atmaximumambienttemperature,
maximum input voltage and peak output (overload) power,
verify drain current waveforms for any signs of transformer
saturation and excessive leading edge current spikes at
E
2/06
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POWERINT [ Power Integrations ]
