TNY284-290
Quick Design Checklist
As with any power supply design, all TinySwitch-4 designs
should be verified on the bench to make sure that component
specifications are not exceeded under worst case conditions.
The following minimum set of tests is strongly recommended:
1. Maximum drain voltage – Verify that VDS does not exceed
67ꢀ V at highest input voltage and peak (overload) output
power. The ꢀ0 V margin to the 72ꢀ V BVDSS specification
gives margin for design variation.
2. Maximum drain current – At maximum ambient temperature,
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
start-up. Repeat under steady-state conditions and verify
that the leading edge current spike event is below ILIMIT(MIN) at
the end of the tLEB(MIN). Under all conditions, the maximum
drain current should be below the specified absolute
maximum ratings.
3. Thermal Check – At specified maximum output power,
minimum input voltage and maximum ambient temperature,
verify that the temperature specifications are not exceeded
for TinySwitch-4, transformer, output diode, and output
capacitors. Enough thermal margin should be allowed for
part-to-part variation of the RDS(ON) of TinySwitch-4 as
specified in the data sheet. Under low-line, maximum
power, a maximum TinySwitch-4 SOURCE pin temperature
of 110 °C is recommended to allow for these variations.
12
Rev. A 09/12
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